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## javax.servlet
Interface RequestDispatcher

All Known Subinterfaces:
  CauchoRequestDispatcher

All Known Implementing Classes:
  QRequestDispatcher

public interface RequestDispatcher

Defines an object that receives requests from the client and sends them to any resource (such as a servlet, HTML file, or JSP file) on the server. The servlet container creates the `RequestDispatcher` object, which is used as a wrapper around a server resource located at a particular path or given by a particular name.

This interface is intended to wrap servlets, but a servlet container can create `RequestDispatcher` objects to wrap any type of resource.

See Also:
  `ServletContext.getRequestDispatcher(java.lang.String)`, `ServletContext.getNamedDispatcher(java.lang.String)`, `ServletRequest.getRequestDispatcher(java.lang.String)`

Method Summary
`void` | `forward(ServletRequest request, ServletResponse response)` Forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server.
`void` | `include(ServletRequest request, ServletResponse response)` Includes the content of a resource (servlet, JSP page, HTML file) in the response.

Method Detail

### forward

    public void forward(ServletRequest request,
                        ServletResponse response)
                 throws ServletException,
                        java.io.IOException

  Forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server. This method allows one servlet to do preliminary processing of a request and another resource to generate the response.

  For a `RequestDispatcher` obtained via `getRequestDispatcher()`, the `ServletRequest` object has its path elements and parameters adjusted to match the path of the target resource.

  `forward` should be called before the response has been committed to the client (before response body output has been flushed). If the response already has been committed, this method throws an `IllegalStateException`. Uncommitted output in the response buffer is automatically cleared before the forward.

  The request and response parameters must be either the same objects as were passed to the calling servlet's service method or be subclasses of the `ServletRequestWrapper` or `ServletResponseWrapper` classes that wrap them.

  Parameters:
    `request` - a `ServletRequest` object that represents the request the client makes of the servlet
    `response` - a `ServletResponse` object that represents the response the servlet returns to the client
  Throws:
    `ServletException` - if the target resource throws this exception
    `java.io.IOException` - if the target resource throws this exception
    `java.lang.IllegalStateException` - if the response was already committed

### include

    public void include(ServletRequest request,
                        ServletResponse response)
                 throws ServletException,
                        java.io.IOException

  Includes the content of a resource (servlet, JSP page, HTML file) in the response. In essence, this method enables programmatic server-side includes.

  The `ServletResponse` object has its path elements and parameters remain unchanged from the caller's. The included servlet cannot change the response status code or set headers; any attempt to make a change is ignored.

  The request and response parameters must be either the same objects as were passed to the calling servlet's service method or be subclasses of the `ServletRequestWrapper` or `ServletResponseWrapper` classes that wrap them.

  Parameters:
    `request` - a `ServletRequest` object that contains the client's request
    `response` - a `ServletResponse` object that contains the servlet's response
  Throws:
    `ServletException` - if the included resource throws this exception
    `java.io.IOException` - if the included resource throws this exception

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