FreemarkerServlet (FreeMarker 2.3.35 API)
Description: declaration: package: freemarker.ext.servlet, class: FreemarkerServlet

Package freemarker.ext.servlet

# Class FreemarkerServlet

java.lang.Object
javax.servlet.GenericServlet
javax.servlet.http.HttpServlet
freemarker.ext.servlet.FreemarkerServlet

All Implemented Interfaces:
  `Serializable`, `javax.servlet.Servlet`, `javax.servlet.ServletConfig`

public class FreemarkerServlet extends javax.servlet.http.HttpServlet
FreeMarker MVC View servlet that can be used similarly to JSP views. That is, you put the variables to expose into HTTP servlet request attributes, then forward to an FTL file (instead of to a JSP file) that's mapped to this servet (usually via the `<url-pattern>*.ftl<url-pattern>`). See web.xml example (and more) in the FreeMarker Manual!

Note that there are two variants of this class: One for the legacy "javax" Servlet API in the `freemarker.ext``.servlet` package, and another for the newer Jakarta Servlet API in the `freemarker.ext``.jakarta.servlet` package (since 2.3.33). Use the variant that fits your Servlet container!

Main features

- It makes all request, request parameters, session, and servlet context attributes available to templates through `Request`, `RequestParameters`, `Session`, and `Application` variables.
- The scope variables are also available via automatic scope discovery. That is, writing `Application.attrName`, `Session.attrName`, `Request.attrName` is not mandatory; it's enough to write `attrName`, and if no such variable was created in the template, it will search the variable in `Request`, and then in `Session`, and finally in `Application`.
- It creates a variable with name `JspTaglibs` that can be used to load JSP taglibs. For example:
  `<#assign dt=JspTaglibs["http://displaytag.sf.net"]>` or `<#assign tiles=JspTaglibs["/WEB-INF/struts-tiles.tld"]>`.
- A custom directive named `include_page` allows you to include the output of another servlet resource from your servlet container, just as if you used `ServletRequest.getRequestDispatcher(path).include()`: `<@include_page path="/myWebapp/somePage.jsp"/>`. You can also pass parameters to the newly included page by passing a hash named `params`: `<@include_page path="/myWebapp/somePage.jsp" params= lang: "en", q="5"}/>`. By default, the request parameters of the original request (the one being processed by FreemarkerServlet) are also inherited by the include. You can explicitly control this inheritance using the `inherit_params` parameter: `<@include_page path="/myWebapp/somePage.jsp" params={lang: "en", q="5"} inherit_params=false/>`.

Supported `init-param`-s

- "TemplatePath": Specifies the location of the template files. By default, this is interpreted as a `ServletContext` resource path, which practically means a web application directory relative path, or a `WEB-INF/lib/*.jar/META-INF/resources`-relative path (note that this last haven't always worked before FreeMarker 2.3.23).
  Alternatively, you can prepend it with `file://` to indicate a literal path in the file system (i.e. `file:///var/www/project/templates/`). Note that three slashes were used to specify an absolute path.
  Also, you can prepend it with `classpath:`, like in `classpath:com/example/templates`, to indicate that you want to load templates from the specified package accessible through the Thread Context Class Loader of the thread that initializes this servlet.
  If `incompatible_improvements` is set to 2.3.22 (or higher), you can specify multiple comma separated locations inside square brackets, like: `[ WEB-INF/templates, classpath:com/example/myapp/templates ]`. This internally creates a `MultiTemplateLoader`. Note again that if `incompatible_improvements` isn't set to at least 2.3.22, the initial `[` has no special meaning, and so this feature is unavailable.
  Any of the above can have a `?setting(name=value, ...)` postfix to set the JavaBeans properties of the `TemplateLoader` created. For example, `/templates?settings(attemptFileAccess=false, URLConnectionUsesCaches=true)` calls `WebappTemplateLoader.setAttemptFileAccess(boolean)` and `WebappTemplateLoader.setURLConnectionUsesCaches(Boolean)` to tune the `WebappTemplateLoader`. For backward compatibility (not recommended!), you can use the `class://` prefix, like in `class://com/example/templates` format, which is similar to `classpath:`, except that it uses the defining class loader of this servlet's class. This can cause template-not-found errors, if that class (in `freemarer.jar` usually) is not local to the web application, while the templates are.
  The default value is `class://` (that is, the root of the class hierarchy), which is not recommended anymore, and should be overwritten with the "TemplatePath" init-param.
- "NoCache": If set to `true`, generates headers in the response that advise the HTTP client not to cache the returned page. If `false`, the HTTP response is not modified for this purpose. The default is `false`.
- "ContentType": The Content-type HTTP header value used in the HTTP responses when nothing else specifies the MIME type. The things that may specify the MIME type (and hence this init-param is ignored), starting with the highest precedence, are:
  1. If the "OverrideResponseContentType" init-param is "never" (the default is "always"), then the value of `ServletResponse.getContentType()` is used if that's non-`null`.
  2. The template's `content_type` custom attribute, usually specified via the `attributes` parameter of the `<#ftl>` directive. This is a legacy feature, deprecated by the `OutputFormat` mechanism.
  3. The output format of the template, if that has non-`null` MIME-type (`OutputFormat.getMimeType()`). When a template has no output format specified, `UndefinedOutputFormat` is used, which has `null` MIME-type. (The output format of a template is deduced from `Configuration` settings, or can be specified directly in the template, like `<#ftl outputFormat="HTML">`. See the FreeMarker Manual for more about the output format mechanism. Note that setting an output format may turns on auto-escaping, so it's not just about MIME types.)
  4. If the "OverrideResponseContentType" init-param is not "always" (the default is "always"), then the value of `ServletResponse.getContentType()` is used if that's non-`null`.
  If none of the above gives a MIME type, then this init-param does. Defaults to `"text/html"`. If and only if the "ResponseCharacterEncoding" init-param is set to "legacy" (which is the default of it), the content type may include the charset (as in `"text/html; charset=utf-8"`), in which case that specifies the actual charset of the output. If the the "ResponseCharacterEncoding" init-param is not set to "legacy", then specifying the charset in the "ContentType" init-param is not allowed, and will cause servlet initialization error.
- "OverrideResponseContentType" (since 2.3.24): Specifies when we should override the `contentType` that might be already set (i.e., non-`null`) in the `HttpServletResponse`. The default is "always", which means that we always set the content type. Another possible value is "never", which means that we don't set the content type in the response, unless `ServletResponse.getContentType()` is `null`. The third possible value is "whenTemplateHasMimeType", which means that we only set the content type if either the template has an associated `OutputFormat` with non-`null` `OutputFormat.getMimeType()`, or it has a custom attribute with name `content_type`, or `ServletResponse.getContentType()` is `null`. Setting this init-param allows you to specify the content type before forwarding to `FreemarkerServlet`.
- "OverrideResponseLocale" (since 2.3.24): Specifies if we should override the template `locale` that might be already set (i.e., non-`null`) in the `HttpServletRequest`. The default is "always", which means that we always deduce the template `locale` by invoking `deduceLocale(String, HttpServletRequest, HttpServletResponse)`. Another possible value is "never", which means that we don't deduce the template `locale`, unless `ServletRequest.getLocale()` is `null`.
- "ResponseCharacterEncoding" (since 2.3.24): Specifies how the `HttpServletResponse` "character encoding" (as in `ServletResponse.setCharacterEncoding(String)`) will be deduced. The possible modes are:
  - "legacy": This is the default for backward compatibility; in new applications, use "fromTemplate" (or some of the other options) instead. "legacy" will use the charset of the template file to set the charset of the servlet response. Except, if the "ContentType" init-param contains a charset, it will use that instead. A quirk of this legacy mode is that it's not aware of the `Configurable.getOutputEncoding()` FreeMarker setting, and thus never reads or writes it (though very few applications utilize that setting anyway). Also, it sets the charset of the servlet response by adding it to the response content type via calling `ServletResponse.setContentType(String)` (as that was the only way before Servlet 2.4), not via the more modern `ServletResponse.setCharacterEncoding(String)` method. Note that the charset of a template usually comes from `Configuration.getDefaultEncoding()` (i.e., from the `default_encoding` FreeMarker setting), occasionally from `Configuration.getEncoding(Locale)` (when FreeMarker was configured to use different charsets depending on the locale) or even more rarely from `Configuration.getTemplateConfigurations()` (when FreeMarker was configured to use a specific charset for certain templates).
  - "fromTemplate": This should be used in most applications, but it's not the default for backward compatibility. It reads the `Configurable.getOutputEncoding()` setting of the template (note that the template usually just inherits that from the `Configuration`), and if that's not set, then reads the source charset of the template, just like "legacy". Then it passes the charset acquired this way to `ServletResponse.setCharacterEncoding(String)` and `Environment.setOutputEncoding(String)`. (It doesn't call the legacy `ServletResponse.setContentType(String)` API to set the charset.) (Note that if the template has a `content_type` template attribute (which is deprecated) that specifies a charset, it will be used as the output charset of that template.)
  - "doNotSet": `FreemarkerServlet` will not set the `HttpServletResponse` "character encoding". It will still call `Environment.setOutputEncoding(String)`, so that the running template will be aware of the charset used for the output.
  - "force " + charset name, for example `force UTF-8`: The output charset will be the one specified after "force" + space, regardless of everything. The charset specified this way is passed to `ServletResponse.setCharacterEncoding(String)` and `Environment.setOutputEncoding(String)`. If the charset name is not recognized by Java, the servlet initialization will fail.
- "BufferSize": Sets the size of the output buffer in bytes, or if "KB" or "MB" is written after the number (like `<param-value>256 KB</param-value>`) then in kilobytes or megabytes. This corresponds to `ServletResponse.setBufferSize(int)`. If the `HttpServletResponse` state doesn't allow changing the buffer size, it will silently do nothing. If this init param isn't specified, then the buffer size is not set by `FreemarkerServlet` in the HTTP response, which usually means that the default buffer size of the servlet container will be used.
- "ExceptionOnMissingTemplate" (since 2.3.22): If `false` (default, but not recommended), if a template is requested that's missing, this servlet responses with a HTTP 404 "Not found" error, and only logs the problem with debug level. If `true` (recommended), the servlet will log the issue with error level, then throws an exception that bubbles up to the servlet container, which usually then creates a HTTP 500 "Internal server error" response (and maybe logs the event into the container log). See "Error handling" later for more!
- "MetaInfTldSources" (since 2.3.22): Comma separated list of items, each is either "webInfPerLibJars", or "classpath" optionally followed by colon and a regular expression, or "clear". For example `<param-value>classpath:.*myoverride.*\.jar$, webInfPerLibJars, classpath:.*taglib.*\.jar$</param-value>`, or `<param-value>classpath</param-value>`. (Whitespace around the commas and list items will be ignored.) See `TaglibFactory.setMetaInfTldSources(List)` for more information. Defaults to a list that contains "webInfPerLibJars" only (can be overridden with `createDefaultMetaInfTldSources()`). Note that this can be also specified with the "org.freemarker.jsp.metaInfTldSources" system property. If both the init-param and the system property exists, the sources listed in the system property will be added after those specified by the init-param. This is where the special entry, "clear" comes handy, as it will remove all previous list items. (An intended usage of the system property is setting it to `clear, classpath` in the Eclipse run configuration if you are running the application without putting the dependency jar-s into `WEB-INF/lib`.) Also, note that further `classpath:<pattern>` items are added automatically at the end of this list based on Jetty's `"org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern"` servlet context attribute.
- "ClasspathTlds" (since 2.3.22): Comma separated list of paths; see `TaglibFactory.setClasspathTlds(List)`. Whitespace around the list items will be ignored. Defaults to no paths (can be overidden with `createDefaultClassPathTlds()`). Note that this can also be specified with the "org.freemarker.jsp.classpathTlds" system property. If both the init-param and the system property exists, the items listed in system property will be added after those specified by the init-param.
- "Debug": Deprecated, has no effect since 2.3.22. (Earlier it has enabled/disabled sending debug-level log messages to the servlet container log, but this servlet doesn't log debug level messages into the servlet container log anymore, only into the FreeMarker log.)
- The following init-params are supported only for backward compatibility, and their usage is discouraged: `TemplateUpdateInterval`, `DefaultEncoding`, `ObjectWrapper`, `TemplateExceptionHandler`. Instead, use init-params with the setting names documented at `Configuration.setSetting(String, String)`, such as `object_wrapper`.
- Any other init-params will be interpreted as `Configuration`-level FreeMarker setting. See the possible names and values at `Configuration.setSetting(String, String)`. Note that these init-param names are starting with lower-case letter (upper-case init-params are used for FreemarkerSerlvet settings).

Error handling

Notes:

- Logging below, where not said otherwise, always refers to logging with FreeMarker's logging facility (see `Logger`), under the "freemarker.servlet" category.
- Throwing a `ServletException` to the servlet container is mentioned at a few places below. That in practice usually means HTTP 500 "Internal server error" response, and maybe a log entry in the servlet container's log.

Errors types:

- If the servlet initialization fails, the servlet won't be started as usual. The cause is usually logged with error level. When it isn't, check the servlet container's log.
- If the requested template doesn't exist, by default the servlet returns a HTTP 404 "Not found" response, and logs the problem with debug level. Responding with HTTP 404 is how JSP behaves, but it's actually not a recommended setting anymore. By setting "ExceptionOnMissingTemplate" init-param to `true` (recommended), it will instead log the problem with error level, then the servlet throws `ServletException` to the servlet container (with the proper cause exception). After all, if the visited URL had an associated "action" but the template behind it is missing, that's an internal server error, not a wrong URL.
- If the template contains parsing errors, it will log it with error level, then the servlet throws `ServletException` to the servlet container (with the proper cause exception).
- If the template throws exception during its execution, and the value of the `template_exception_handler` init-param is `rethrow` (recommended), it will log it with error level and then the servlet throws `ServletException` to the servlet container (with the proper cause exception). But beware, the default value of the `template_exception_handler` init-param is `html_debug`, which is for development only! Set it to `rethrow` for production. The `html_debug` (and `debug`) handlers will print error details to the page and then commit the HTTP response with response code 200 "OK", thus, the server wont be able roll back the response and send back an HTTP 500 page. This is so that the template developers will see the error without digging the logs.

See Also:
  Serialized Form

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected boolean`
  `debug`
  Deprecated.
  Not used anymore; to enable/disable debug logging, just set the logging level of the logging library used by `Logger`.
  `static String`
  `INIT_PARAM_BUFFER_SIZE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_CLASSPATH_TLDS`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_CONTENT_TYPE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_EXCEPTION_ON_MISSING_TEMPLATE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_META_INF_TLD_LOCATIONS`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_NO_CACHE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_OVERRIDE_RESPONSE_CONTENT_TYPE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_OVERRIDE_RESPONSE_LOCALE`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_RESPONSE_CHARACTER_ENCODING`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_TEMPLATE_PATH`
  Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
  `static String`
  `INIT_PARAM_VALUE_ALWAYS`
  `static String`
  `INIT_PARAM_VALUE_DO_NOT_SET`
  `static String`
  `INIT_PARAM_VALUE_FORCE_PREFIX`
  `static String`
  `INIT_PARAM_VALUE_FROM_TEMPLATE`
  `static String`
  `INIT_PARAM_VALUE_LEGACY`
  `static String`
  `INIT_PARAM_VALUE_NEVER`
  `static String`
  `INIT_PARAM_VALUE_WHEN_TEMPLATE_HAS_MIME_TYPE`
  `static String`
  `KEY_APPLICATION`
  `static String`
  `KEY_APPLICATION_PRIVATE`
  `static String`
  `KEY_INCLUDE`
  `static String`
  `KEY_JSP_TAGLIBS`
  `static String`
  `KEY_REQUEST`
  `static String`
  `KEY_REQUEST_PARAMETERS`
  `static String`
  `KEY_REQUEST_PRIVATE`
  `static String`
  `KEY_SESSION`
  `static String`
  `META_INF_TLD_LOCATION_CLASSPATH`
  Used as part of the value of the "MetaInfTldSources" init-param.
  `static String`
  `META_INF_TLD_LOCATION_CLEAR`
  Used as part of the value of the "MetaInfTldSources" init-param.
  `static String`
  `META_INF_TLD_LOCATION_WEB_INF_PER_LIB_JARS`
  Used as part of the value of the "MetaInfTldSources" init-param.
  `static long`
  `serialVersionUID`
  `static String`
  `SYSTEM_PROPERTY_CLASSPATH_TLDS`
  When set, the items defined in it will be added after those coming from the "ClasspathTlds" init-param.
  `static String`
  `SYSTEM_PROPERTY_META_INF_TLD_SOURCES`
  When set, the items defined in it will be added after those coming from the "MetaInfTldSources" init-param.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `FreemarkerServlet()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected Configuration`
  `createConfiguration()`
  Creates the FreeMarker `Configuration` singleton and (when overidden) maybe sets its defaults.
  `protected List`
  `createDefaultClassPathTlds()`
  Creates the default of the "ClasspathTlds" init-param; if this init-param is specified, it will be appended after the default, not replace it.
  `protected List`
  `createDefaultMetaInfTldSources()`
  Creates the default of the "MetaInfTldSources" init-param; if this init-param is specified, it will completelly replace the default value.
  `protected ObjectWrapper`
  `createDefaultObjectWrapper()`
  Override this to specify what the default `ObjectWrapper` will be when the `object_wrapper` Servlet init-param wasn't specified.
  `protected TemplateModel`
  `createModel​(ObjectWrapper objectWrapper, javax.servlet.ServletContext servletContext, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  `protected ObjectWrapper`
  `createObjectWrapper()`
  Called from `init()` to create the `ObjectWrapper`; to customzie this aspect, in most cases you should override `createDefaultObjectWrapper()` instead.
  `protected HttpRequestParametersHashModel`
  `createRequestParametersHashModel​(javax.servlet.http.HttpServletRequest request)`
  `protected TaglibFactory`
  `createTaglibFactory​(ObjectWrapper objectWrapper, javax.servlet.ServletContext servletContext)`
  Called to create the `TaglibFactory` once per servlet context.
  `protected TemplateLoader`
  `createTemplateLoader​(String templatePath)`
  Create the template loader.
  `protected Locale`
  `deduceLocale​(String templatePath, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  Returns the locale used for the `Configuration.getTemplate(String, Locale)` call (as far as the "OverrideResponseLocale" Servlet init-param allows that).
  `void`
  `doGet​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  `void`
  `doPost​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  `protected Configuration`
  `getConfiguration()`
  Returns the `Configuration` object used by this servlet.
  `protected String`
  `getDefaultOverrideResponseContentType()`
  Returns the default value of the "OverrideResponseContentType" Servlet init-param.
  `protected ObjectWrapper`
  `getObjectWrapper()`
  Should be final; don't override it.
  `protected String`
  `getTemplatePath()`
  Deprecated.
  Not called by FreeMarker code, and there's no point to override this (unless to cause confusion).
  `void`
  `init()`
  Don't override this method to adjust FreeMarker settings! Override the protected methods for that, such as `createConfiguration()`, `createTemplateLoader(String)`, `createDefaultObjectWrapper()`, etc.
  `protected void`
  `initializeServletContext​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  Called when servlet detects in a request processing that application-global (that is, ServletContext-specific) attributes are not yet set.
  `protected void`
  `initializeSession​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  Called when servlet detects in a request processing that session-global (that is, HttpSession-specific) attributes are not yet set.
  `protected void`
  `postTemplateProcess​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Template template, TemplateModel data)`
  Called after the execution returns from `Template.process(Object, java.io.Writer)`.
  `protected boolean`
  `preprocessRequest​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  Called as the first step in request processing, before the templating mechanism is put to work.
  `protected boolean`
  `preTemplateProcess​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Template template, TemplateModel model)`
  Called before the execution is passed to `Template.process(Object, java.io.Writer)`.
  `protected void`
  `processEnvironment​(Environment env, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)`
  This is the method that actually executes the template.
  `protected String`
  `requestUrlToTemplatePath​(javax.servlet.http.HttpServletRequest request)`
  Maps the request URL to a template path (template name) that is passed to `Configuration.getTemplate(String, Locale)`.
  `protected void`
  `setConfigurationDefaults()`
  Sets the defaults of the configuration that are specific to the `FreemarkerServlet` subclass.

  ### Methods inherited from class javax.servlet.http.HttpServlet

  `doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service`

  ### Methods inherited from class javax.servlet.GenericServlet

  `destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### serialVersionUID

    public static final long serialVersionUID
    See Also:
      Constant Field Values

  - ### INIT_PARAM_TEMPLATE_PATH

    public static final String INIT_PARAM_TEMPLATE_PATH
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params. (This init-param has existed long before 2.3.22, but this constant was only added then.)
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_NO_CACHE

    public static final String INIT_PARAM_NO_CACHE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params. (This init-param has existed long before 2.3.22, but this constant was only added then.)
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_CONTENT_TYPE

    public static final String INIT_PARAM_CONTENT_TYPE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params. (This init-param has existed long before 2.3.22, but this constant was only added then.)
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_OVERRIDE_RESPONSE_CONTENT_TYPE

    public static final String INIT_PARAM_OVERRIDE_RESPONSE_CONTENT_TYPE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.24
    See Also:
      Constant Field Values

  - ### INIT_PARAM_RESPONSE_CHARACTER_ENCODING

    public static final String INIT_PARAM_RESPONSE_CHARACTER_ENCODING
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.24
    See Also:
      Constant Field Values

  - ### INIT_PARAM_OVERRIDE_RESPONSE_LOCALE

    public static final String INIT_PARAM_OVERRIDE_RESPONSE_LOCALE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.24
    See Also:
      Constant Field Values

  - ### INIT_PARAM_BUFFER_SIZE

    public static final String INIT_PARAM_BUFFER_SIZE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_META_INF_TLD_LOCATIONS

    public static final String INIT_PARAM_META_INF_TLD_LOCATIONS
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_EXCEPTION_ON_MISSING_TEMPLATE

    public static final String INIT_PARAM_EXCEPTION_ON_MISSING_TEMPLATE
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_CLASSPATH_TLDS

    public static final String INIT_PARAM_CLASSPATH_TLDS
    Init-param name - see the `FreemarkerServlet` class documentation about the init-params.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_NEVER

    public static final String INIT_PARAM_VALUE_NEVER
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_ALWAYS

    public static final String INIT_PARAM_VALUE_ALWAYS
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_WHEN_TEMPLATE_HAS_MIME_TYPE

    public static final String INIT_PARAM_VALUE_WHEN_TEMPLATE_HAS_MIME_TYPE
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_FROM_TEMPLATE

    public static final String INIT_PARAM_VALUE_FROM_TEMPLATE
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_LEGACY

    public static final String INIT_PARAM_VALUE_LEGACY
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_DO_NOT_SET

    public static final String INIT_PARAM_VALUE_DO_NOT_SET
    See Also:
      Constant Field Values

  - ### INIT_PARAM_VALUE_FORCE_PREFIX

    public static final String INIT_PARAM_VALUE_FORCE_PREFIX
    See Also:
      Constant Field Values

  - ### SYSTEM_PROPERTY_META_INF_TLD_SOURCES

    public static final String SYSTEM_PROPERTY_META_INF_TLD_SOURCES
    When set, the items defined in it will be added after those coming from the "MetaInfTldSources" init-param. The value syntax is the same as of the init-param. Note that "clear" can be used to re-start the list, rather than continue it.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### SYSTEM_PROPERTY_CLASSPATH_TLDS

    public static final String SYSTEM_PROPERTY_CLASSPATH_TLDS
    When set, the items defined in it will be added after those coming from the "ClasspathTlds" init-param. The value syntax is the same as of the init-param.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### META_INF_TLD_LOCATION_WEB_INF_PER_LIB_JARS

    public static final String META_INF_TLD_LOCATION_WEB_INF_PER_LIB_JARS
    Used as part of the value of the "MetaInfTldSources" init-param.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### META_INF_TLD_LOCATION_CLASSPATH

    public static final String META_INF_TLD_LOCATION_CLASSPATH
    Used as part of the value of the "MetaInfTldSources" init-param.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### META_INF_TLD_LOCATION_CLEAR

    public static final String META_INF_TLD_LOCATION_CLEAR
    Used as part of the value of the "MetaInfTldSources" init-param.
    Since:
      2.3.22
    See Also:
      Constant Field Values

  - ### KEY_REQUEST

    public static final String KEY_REQUEST
    See Also:
      Constant Field Values

  - ### KEY_INCLUDE

    public static final String KEY_INCLUDE
    See Also:
      Constant Field Values

  - ### KEY_REQUEST_PRIVATE

    public static final String KEY_REQUEST_PRIVATE
    See Also:
      Constant Field Values

  - ### KEY_REQUEST_PARAMETERS

    public static final String KEY_REQUEST_PARAMETERS
    See Also:
      Constant Field Values

  - ### KEY_SESSION

    public static final String KEY_SESSION
    See Also:
      Constant Field Values

  - ### KEY_APPLICATION

    public static final String KEY_APPLICATION
    See Also:
      Constant Field Values

  - ### KEY_APPLICATION_PRIVATE

    public static final String KEY_APPLICATION_PRIVATE
    See Also:
      Constant Field Values

  - ### KEY_JSP_TAGLIBS

    public static final String KEY_JSP_TAGLIBS
    See Also:
      Constant Field Values

  - ### debug

    @Deprecated protected boolean debug
    Deprecated.
    Not used anymore; to enable/disable debug logging, just set the logging level of the logging library used by `Logger`.

- ## Constructor Details

  - ### FreemarkerServlet

    public FreemarkerServlet()

- ## Method Details

  - ### init

    public void init() throws javax.servlet.ServletException
    Don't override this method to adjust FreeMarker settings! Override the protected methods for that, such as `createConfiguration()`, `createTemplateLoader(String)`, `createDefaultObjectWrapper()`, etc. Also note that lot of things can be changed with init-params instead of overriding methods, so if you override settings, usually you should only override their defaults.
    Overrides:
      `init` in class `javax.servlet.GenericServlet`
    Throws:
      `javax.servlet.ServletException`

  - ### createTemplateLoader

    protected TemplateLoader createTemplateLoader​(String templatePath) throws IOException
    Create the template loader. The default implementation will create a `ClassTemplateLoader` if the template path starts with `"class://"`, a `FileTemplateLoader` if the template path starts with `"file://"`, and a `WebappTemplateLoader` otherwise. Also, if `incompatible_improvements` is 2.3.22 or higher, it will create a `MultiTemplateLoader` if the template path starts with `"["`.
    Parameters:
      `templatePath` - the template path to create a loader for
    Returns:
      a newly created template loader
    Throws:
      `IOException`

  - ### doGet

    public void doGet​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException
    Overrides:
      `doGet` in class `javax.servlet.http.HttpServlet`
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### doPost

    public void doPost​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException
    Overrides:
      `doPost` in class `javax.servlet.http.HttpServlet`
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### processEnvironment

    protected void processEnvironment​(Environment env, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws TemplateException, IOException
    This is the method that actually executes the template. The original implementation coming from `FreemarkerServlet` simply calls `Environment.process()`. Overriding this method allows you to prepare the `Environment` before the execution, or extract information from the `Environment` after the execution. It also allows you to capture exceptions throw by the template.
    Parameters:
      `env` - The `Environment` object already set up to execute the template. You only have to call `Environment.process()` and the output will be produced by the template.
    Throws:
      `TemplateException`
      `IOException`
    Since:
      2.3.24

  - ### deduceLocale

    protected Locale deduceLocale​(String templatePath, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException
    Returns the locale used for the `Configuration.getTemplate(String, Locale)` call (as far as the "OverrideResponseLocale" Servlet init-param allows that). The base implementation in `FreemarkerServlet` simply returns the `locale` setting of the configuration. Override this method to provide different behavior, for example, to use the locale indicated in the HTTP request.
    Parameters:
      `templatePath` - The template path (template name) as it will be passed to `Configuration.getTemplate(String)`. (Not to be confused with the servlet init-param of identical name; they aren't related.)
    Throws:
      `javax.servlet.ServletException` - Can be thrown since 2.3.22, if the locale can't be deduced from the URL.

  - ### createModel

    protected TemplateModel createModel​(ObjectWrapper objectWrapper, javax.servlet.ServletContext servletContext, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws TemplateModelException
    Throws:
      `TemplateModelException`

  - ### createTaglibFactory

    protected TaglibFactory createTaglibFactory​(ObjectWrapper objectWrapper, javax.servlet.ServletContext servletContext) throws TemplateModelException
    Called to create the `TaglibFactory` once per servlet context. The default implementation configures it based on the servlet-init parameters and various other environmental settings, so if you override this method, you should call super, then adjust the result.
    Throws:
      `TemplateModelException`
    Since:
      2.3.22

  - ### createDefaultClassPathTlds

    protected List createDefaultClassPathTlds()
    Creates the default of the "ClasspathTlds" init-param; if this init-param is specified, it will be appended after the default, not replace it.

    The implementation in `FreemarkerServlet` returns `TaglibFactory.DEFAULT_CLASSPATH_TLDS`.

    Returns:
      A `List` of `String`-s; not `null`.
    Since:
      2.3.22

  - ### createDefaultMetaInfTldSources

    protected List createDefaultMetaInfTldSources()
    Creates the default of the "MetaInfTldSources" init-param; if this init-param is specified, it will completelly replace the default value.

    The implementation in `FreemarkerServlet` returns `TaglibFactory.DEFAULT_META_INF_TLD_SOURCES`.

    Returns:
      A `List` of `TaglibFactory.MetaInfTldSource`-s; not `null`.
    Since:
      2.3.22

  - ### requestUrlToTemplatePath

    protected String requestUrlToTemplatePath​(javax.servlet.http.HttpServletRequest request) throws javax.servlet.ServletException
    Maps the request URL to a template path (template name) that is passed to `Configuration.getTemplate(String, Locale)`. You can override it (i.e. to provide advanced rewriting capabilities), but you are strongly encouraged to call the overridden method first, then only modify its return value.
    Parameters:
      `request` - The currently processed HTTP request
    Returns:
      The template path (template name); can't be `null`. This is what's passed to `Configuration.getTemplate(String)` later. (Not to be confused with the `templatePath` servlet init-param of identical name; that basically specifies the "virtual file system" to which this will be relative to.)
    Throws:
      `javax.servlet.ServletException` - Can be thrown since 2.3.22, if the template path can't be deduced from the URL.

  - ### preprocessRequest

    protected boolean preprocessRequest​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException
    Called as the first step in request processing, before the templating mechanism is put to work. By default does nothing and returns false. This method is typically overridden to manage serving of non-template resources (i.e. images) that reside in the template directory.
    Parameters:
      `request` - the HTTP request
      `response` - the HTTP response
    Returns:
      true to indicate this method has processed the request entirely, and that the further request processing should not take place.
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### createConfiguration

    protected Configuration createConfiguration()
    Creates the FreeMarker `Configuration` singleton and (when overidden) maybe sets its defaults. Servlet init-params will be applied later, and thus can overwrite the settings specified here.

    By overriding this method you can set your preferred `Configuration` setting defaults, as only the settings for which an init-param was specified will be overwritten later. (Note that `FreemarkerServlet` also has its own defaults for a few settings, but since 2.3.22, the servlet detects if those settings were already set here and then it won't overwrite them.)

    The default implementation simply creates a new instance with `Configuration()` and returns it.

  - ### setConfigurationDefaults

    protected void setConfigurationDefaults()
    Sets the defaults of the configuration that are specific to the `FreemarkerServlet` subclass. This is called after the common (wired in) `FreemarkerServlet` setting defaults was set, also the

  - ### createObjectWrapper

    protected ObjectWrapper createObjectWrapper()
    Called from `init()` to create the `ObjectWrapper`; to customzie this aspect, in most cases you should override `createDefaultObjectWrapper()` instead. Overriding this method is necessary when you want to customize how the `ObjectWrapper` is created from the init-param values, or you want to do some post-processing (like checking) on the created `ObjectWrapper`. To customize init-param interpretation, call `GenericServlet.getInitParameter(String)` with `Configurable.OBJECT_WRAPPER_KEY` as argument, and see if it returns a value that you want to interpret yourself. If was `null` or you don't want to interpret the value, fall back to the super method.

    The default implementation interprets the `object_wrapper` servlet init-param with calling `Configurable.setSetting(String, String)` (see valid values there), or if there's no such servlet init-param, then it calls `createDefaultObjectWrapper()`.

    Returns:
      The `ObjectWrapper` that will be used for adapting request, session, and servlet context attributes to `TemplateModel`-s, and also as the object wrapper setting of `Configuration`.

  - ### createDefaultObjectWrapper

    protected ObjectWrapper createDefaultObjectWrapper()
    Override this to specify what the default `ObjectWrapper` will be when the `object_wrapper` Servlet init-param wasn't specified. Note that this is called by `createConfiguration()`, and so if that was also overidden but improperly then this method might won't be ever called. Also note that if you set the `object_wrapper` in `createConfiguration()`, then this won't be called, since then that has already specified the default.

    The default implementation calls `Configuration.getDefaultObjectWrapper(freemarker.template.Version)`. You should also pass in the version paramter when creating an `ObjectWrapper` that supports that. You can get the version by calling `getConfiguration()` and then `Configuration.getIncompatibleImprovements()`.

    Since:
      2.3.22

  - ### getObjectWrapper

    protected ObjectWrapper getObjectWrapper()
    Should be final; don't override it. Override `createObjectWrapper()` instead.

  - ### getTemplatePath

    @Deprecated protected final String getTemplatePath()
    Deprecated.
    Not called by FreeMarker code, and there's no point to override this (unless to cause confusion).
    The value of the `TemplatePath` init-param. `null` if the `template_loader` setting was set in a custom `createConfiguration()`.

  - ### createRequestParametersHashModel

    protected HttpRequestParametersHashModel createRequestParametersHashModel​(javax.servlet.http.HttpServletRequest request)

  - ### initializeServletContext

    protected void initializeServletContext​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException
    Called when servlet detects in a request processing that application-global (that is, ServletContext-specific) attributes are not yet set. This is a generic hook you might use in subclasses to perform a specific action on first request in the context. By default it does nothing.
    Parameters:
      `request` - the actual HTTP request
      `response` - the actual HTTP response
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### initializeSession

    protected void initializeSession​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException
    Called when servlet detects in a request processing that session-global (that is, HttpSession-specific) attributes are not yet set. This is a generic hook you might use in subclasses to perform a specific action on first request in the session. By default it does nothing. It is only invoked on newly created sessions; it's not invoked when a replicated session is reinstantiated in another servlet container.
    Parameters:
      `request` - the actual HTTP request
      `response` - the actual HTTP response
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### preTemplateProcess

    protected boolean preTemplateProcess​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Template template, TemplateModel model) throws javax.servlet.ServletException, IOException
    Called before the execution is passed to `Template.process(Object, java.io.Writer)`. This is a generic hook you might use in subclasses to perform a specific action before the template is processed.
    Parameters:
      `request` - The HTTP request that we will response to.
      `response` - The HTTP response. The HTTP headers are already initialized here, such as the `conteType` and the `responseCharacterEncoding` are already set, but you can do the final adjustments here. The response `Writer` isn't created yet, so changing HTTP headers and buffering parameters works.
      `template` - The template that will get executed
      `model` - The data model that will be passed to the template. By default this will be an `AllHttpScopesHashModel` (which is a `SimpleHash` subclass). Thus, you can add new variables to the data-model with the `SimpleHash.put(String, Object)` subclass) method. However, to adjust the data-model, overriding `createModel(ObjectWrapper, ServletContext, HttpServletRequest, HttpServletResponse)` is probably a more appropriate place.
    Returns:
      true to process the template, false to suppress template processing.
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### postTemplateProcess

    protected void postTemplateProcess​(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, Template template, TemplateModel data) throws javax.servlet.ServletException, IOException
    Called after the execution returns from `Template.process(Object, java.io.Writer)`. This is a generic hook you might use in subclasses to perform a specific action after the template is processed. It will be invoked even if the template processing throws an exception. By default does nothing.
    Parameters:
      `request` - the actual HTTP request
      `response` - the actual HTTP response
      `template` - the template that was executed
      `data` - the data that was passed to the template
    Throws:
      `javax.servlet.ServletException`
      `IOException`

  - ### getConfiguration

    protected Configuration getConfiguration()
    Returns the `Configuration` object used by this servlet. Please don't forget that `Configuration` is not thread-safe when you modify it.

  - ### getDefaultOverrideResponseContentType

    protected String getDefaultOverrideResponseContentType()
    Returns the default value of the "OverrideResponseContentType" Servlet init-param. The method inherited from `FreemarkerServlet` returns "always"; subclasses my override this.
    Since:
      2.3.24