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Interface javax.servlet.RequestDispatcher

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:
getRequestDispatcher, getNamedDispatcher, getRequestDispatcher

Method Index

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

Methods

o forward 
 public abstract void forward(ServletRequest request,
                              ServletResponse response) throws ServletException, 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 {@link ServletRequestWrapper} or {@link ServletResponseWrapper} classes that wrap them.

Parameters:
request - a {@link ServletRequest} object that represents the request the client makes of the servlet
response - a {@link ServletResponse} object that represents the response the servlet returns to the client
Throws: ServletException
if the target resource throws this exception
Throws: IOException
if the target resource throws this exception
Throws: IllegalStateException
if the response was already committed
o include 
 public abstract void include(ServletRequest request,
                              ServletResponse response) throws ServletException, 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 {@link 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 {@link ServletRequestWrapper} or {@link ServletResponseWrapper} classes that wrap them.

Parameters:
request - a {@link ServletRequest} object that contains the client's request
response - a {@link ServletResponse} object that contains the servlet's response
Throws: ServletException
if the included resource throws this exception
Throws: IOException
if the included resource throws this exception 
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