RequestFilter (Apache Tomcat 8.5.57 API Documentation)

org.apache.catalina.filters

## Class RequestFilter

- java.lang.Object
- - org.apache.catalina.filters.FilterBase
  - - org.apache.catalina.filters.RequestFilter

- All Implemented Interfaces:
    Filter
  Direct Known Subclasses:
    RemoteAddrFilter, RemoteHostFilter

      public abstract class RequestFilter
      extends FilterBase

  Implementation of a Filter that performs filtering based on comparing the appropriate request property (selected based on which subclass you choose to configure into your Container's pipeline) against the regular expressions configured for this Filter.

  This filter is configured by setting the `allow` and/or `deny` properties to a regular expressions (in the syntax supported by `Pattern`) to which the appropriate request property will be compared. Evaluation proceeds as follows:

  - The subclass extracts the request property to be filtered, and calls the common `process()` method.
  - If there is a deny expression configured, the property will be compared to the expression. If a match is found, this request will be rejected with a "Forbidden" HTTP response.
  - If there is a allow expression configured, the property will be compared to the expression. If a match is found, this request will be allowed to pass through to the next filter in the current pipeline.
  - If a deny expression was specified but no allow expression, allow this request to pass through (because none of the deny expressions matched it).
  - The request will be rejected with a "Forbidden" HTTP response.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Pattern` | `allow` The regular expression used to test for allowed requests.
    `protected Pattern` | `deny` The regular expression used to test for denied requests.
    `protected int` | `denyStatus` The HTTP response status code that is used when rejecting denied request.

    - ### Fields inherited from class org.apache.catalina.filters.FilterBase

      `sm`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `RequestFilter()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract void` | `doFilter(ServletRequest request, ServletResponse response, FilterChain chain)` Extract the desired request property, and pass it (along with the specified request and response objects) to the protected `process()` method to perform the actual filtering.
    `String` | `getAllow()`
    `String` | `getDeny()`
    `int` | `getDenyStatus()`
    `protected boolean` | `isConfigProblemFatal()` Determines if an exception when calling a setter or an unknown configuration attribute triggers the failure of the this filter which in turn will prevent the web application from starting.
    `protected void` | `process(String property, ServletRequest request, ServletResponse response, FilterChain chain)` Perform the filtering that has been configured for this Filter, matching against the specified request property.
    `void` | `setAllow(String allow)` Set the regular expression used to test for allowed requests for this Filter, if any.
    `void` | `setDeny(String deny)` Set the regular expression used to test for denied requests for this Filter, if any.
    `void` | `setDenyStatus(int denyStatus)` Set response status code that is used to reject denied request.

    - ### Methods inherited from class org.apache.catalina.filters.FilterBase

      `destroy, getLogger, init`

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

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

- - ### Field Detail

    - #### allow

          protected Pattern allow

      The regular expression used to test for allowed requests.

    - #### deny

          protected Pattern deny

      The regular expression used to test for denied requests.

    - #### denyStatus

          protected int denyStatus

      The HTTP response status code that is used when rejecting denied request. It is 403 by default, but may be changed to be 404.

  - ### Constructor Detail

    - #### RequestFilter

          public RequestFilter()

  - ### Method Detail

    - #### getAllow

          public String getAllow()

      Returns:
        the regular expression used to test for allowed requests for this Filter, if any; otherwise, return `null`.

    - #### setAllow

          public void setAllow(String allow)

      Set the regular expression used to test for allowed requests for this Filter, if any.
      Parameters:
        `allow` - The new allow expression

    - #### getDeny

          public String getDeny()

      Returns:
        the regular expression used to test for denied requests for this Filter, if any; otherwise, return `null`.

    - #### setDeny

          public void setDeny(String deny)

      Set the regular expression used to test for denied requests for this Filter, if any.
      Parameters:
        `deny` - The new deny expression

    - #### getDenyStatus

          public int getDenyStatus()

      Returns:
        response status code that is used to reject denied request.

    - #### setDenyStatus

          public void setDenyStatus(int denyStatus)

      Set response status code that is used to reject denied request.
      Parameters:
        `denyStatus` - The status code for deny

    - #### doFilter

          public abstract void doFilter(ServletRequest request,
                      ServletResponse response,
                      FilterChain chain)
                                 throws IOException,
                                        ServletException

      Extract the desired request property, and pass it (along with the specified request and response objects) to the protected `process()` method to perform the actual filtering. This method must be implemented by a concrete subclass.
      Parameters:
        `request` - The servlet request to be processed
        `response` - The servlet response to be created
        `chain` - The filter chain
      Throws:
        `IOException` - if an input/output error occurs
        `ServletException` - if a servlet error occurs

    - #### isConfigProblemFatal

          protected boolean isConfigProblemFatal()

      Description copied from class: `FilterBase`
      Determines if an exception when calling a setter or an unknown configuration attribute triggers the failure of the this filter which in turn will prevent the web application from starting.
      Overrides:
        `isConfigProblemFatal` in class `FilterBase`
      Returns:
        `true` if a problem should trigger the failure of this filter, else `false`

    - #### process

          protected void process(String property,
                     ServletRequest request,
                     ServletResponse response,
                     FilterChain chain)
                          throws IOException,
                                 ServletException

      Perform the filtering that has been configured for this Filter, matching against the specified request property.
      Parameters:
        `property` - The request property on which to filter
        `request` - The servlet request to be processed
        `response` - The servlet response to be processed
        `chain` - The filter chain
      Throws:
        `IOException` - if an input/output error occurs
        `ServletException` - if a servlet error occurs

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