org.springframework.web.filter

## Class HiddenHttpMethodFilter

- java.lang.Object
- - org.springframework.web.filter.GenericFilterBean
  - - org.springframework.web.filter.OncePerRequestFilter
    - - org.springframework.web.filter.HiddenHttpMethodFilter

- All Implemented Interfaces:
    Filter, Aware, BeanNameAware, DisposableBean, InitializingBean, EnvironmentAware, ServletContextAware

      public class HiddenHttpMethodFilter
      extends OncePerRequestFilter

  `Filter` that converts posted method parameters into HTTP methods, retrievable via `HttpServletRequest.getMethod()`. Since browsers currently only support GET and POST, a common technique - used by the Prototype library, for instance - is to use a normal POST with an additional hidden form field (`_method`) to pass the "real" HTTP method along. This filter reads that parameter and changes the `HttpServletRequestWrapper.getMethod()` return value accordingly.

  The name of the request parameter defaults to `_method`, but can be adapted via the `methodParam` property.

  NOTE: This filter needs to run after multipart processing in case of a multipart POST request, due to its inherent need for checking a POST body parameter. So typically, put a Spring `MultipartFilter` before this HiddenHttpMethodFilter in your `web.xml` filter chain.

  Since:
    3.0
  Author:
    Arjen Poutsma

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static String` | `DEFAULT_METHOD_PARAM` Default method parameter: `_method`

    - ### Fields inherited from class org.springframework.web.filter.OncePerRequestFilter

      `ALREADY_FILTERED_SUFFIX`

    - ### Fields inherited from class org.springframework.web.filter.GenericFilterBean

      `logger`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `HiddenHttpMethodFilter()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)` Same contract as for `doFilter`, but guaranteed to be just invoked once per request within a single request thread.
    `void` | `setMethodParam(String methodParam)` Set the parameter name to look for HTTP methods.

    - ### Methods inherited from class org.springframework.web.filter.OncePerRequestFilter

      `doFilter, getAlreadyFilteredAttributeName, isAsyncDispatch, isAsyncStarted, shouldNotFilter, shouldNotFilterAsyncDispatch, shouldNotFilterErrorDispatch`

    - ### Methods inherited from class org.springframework.web.filter.GenericFilterBean

      `addRequiredProperty, afterPropertiesSet, destroy, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setEnvironment, setServletContext`

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

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

- - ### Field Detail

    - #### DEFAULT_METHOD_PARAM

          public static final String DEFAULT_METHOD_PARAM

      Default method parameter: `_method`
      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### HiddenHttpMethodFilter

          public HiddenHttpMethodFilter()

  - ### Method Detail

    - #### setMethodParam

          public void setMethodParam(String methodParam)

      Set the parameter name to look for HTTP methods.
      See Also:
        `DEFAULT_METHOD_PARAM`

    - #### doFilterInternal

          protected void doFilterInternal(HttpServletRequest request,
                              HttpServletResponse response,
                              FilterChain filterChain)
                                   throws ServletException,
                                          IOException

      Description copied from class: `OncePerRequestFilter`
      Same contract as for `doFilter`, but guaranteed to be just invoked once per request within a single request thread. See `OncePerRequestFilter.shouldNotFilterAsyncDispatch()` for details.

      Provides HttpServletRequest and HttpServletResponse arguments instead of the default ServletRequest and ServletResponse ones.

      Specified by:
        `doFilterInternal` in class `OncePerRequestFilter`
      Throws:
        `ServletException`
        `IOException`