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:

ServletContext.getRequestDispatcher(java.lang.String), ServletContext.getNamedDispatcher(java.lang.String), ServletRequest.getRequestDispatcher(java.lang.String)

Field Summary

Fields
Modifier and Type	Field and Description
`static java.lang.String`	`ERROR_EXCEPTION` The name of the request attribute under which the exception object is propagated during an error dispatch
`static java.lang.String`	`ERROR_EXCEPTION_TYPE` The name of the request attribute under which the type of the exception object is propagated during an error dispatch
`static java.lang.String`	`ERROR_MESSAGE` The name of the request attribute under which the exception message is propagated during an error dispatch
`static java.lang.String`	`ERROR_REQUEST_URI` The name of the request attribute under which the request URI whose processing caused the error is propagated during an error dispatch
`static java.lang.String`	`ERROR_SERVLET_NAME` The name of the request attribute under which the name of the servlet in which the error occurred is propagated during an error dispatch
`static java.lang.String`	`ERROR_STATUS_CODE` The name of the request attribute under which the response status is propagated during an error dispatch
`static java.lang.String`	`FORWARD_CONTEXT_PATH` The name of the request attribute under which the original context path is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_MAPPING` The name of the request attribute under which the original `HttpServletMapping` is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_PATH_INFO` The name of the request attribute under which the original path info is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_QUERY_STRING` The name of the request attribute under which the original query string is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_REQUEST_URI` The name of the request attribute under which the original request URI is made available to the target of a `forward`
`static java.lang.String`	`FORWARD_SERVLET_PATH` The name of the request attribute under which the original servlet path is made available to the target of a `forward`
`static java.lang.String`	`INCLUDE_CONTEXT_PATH` The name of the request attribute under which the context path of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_MAPPING` The name of the request attribute under which the `HttpServletMapping` of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_PATH_INFO` The name of the request attribute under which the path info of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_QUERY_STRING` The name of the request attribute under which the query string of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_REQUEST_URI` The name of the request attribute under which the request URI of the target of an `include` is stored
`static java.lang.String`	`INCLUDE_SERVLET_PATH` The name of the request attribute under which the servlet path of the target of an `include` is stored

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`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.

- Field Detail
  - FORWARD_REQUEST_URI
```
static final java.lang.String FORWARD_REQUEST_URI
```
    The name of the request attribute under which the original request URI is made available to the target of a forward
    
    See Also:
    
    Constant Field Values
  - FORWARD_CONTEXT_PATH
```
static final java.lang.String FORWARD_CONTEXT_PATH
```
    The name of the request attribute under which the original context path is made available to the target of a forward
    
    See Also:
    
    Constant Field Values
  - FORWARD_MAPPING
```
static final java.lang.String FORWARD_MAPPING
```
    The name of the request attribute under which the original HttpServletMapping is made available to the target of a forward
    
    Since:
    
    4.0
    
    See Also:
    
    Constant Field Values
  - FORWARD_PATH_INFO
```
static final java.lang.String FORWARD_PATH_INFO
```
    The name of the request attribute under which the original path info is made available to the target of a forward
    
    See Also:
    
    Constant Field Values
  - FORWARD_SERVLET_PATH
```
static final java.lang.String FORWARD_SERVLET_PATH
```
    The name of the request attribute under which the original servlet path is made available to the target of a forward
    
    See Also:
    
    Constant Field Values
  - FORWARD_QUERY_STRING
```
static final java.lang.String FORWARD_QUERY_STRING
```
    The name of the request attribute under which the original query string is made available to the target of a forward
    
    See Also:
    
    Constant Field Values
  - INCLUDE_REQUEST_URI
```
static final java.lang.String INCLUDE_REQUEST_URI
```
    The name of the request attribute under which the request URI of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - INCLUDE_CONTEXT_PATH
```
static final java.lang.String INCLUDE_CONTEXT_PATH
```
    The name of the request attribute under which the context path of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - INCLUDE_PATH_INFO
```
static final java.lang.String INCLUDE_PATH_INFO
```
    The name of the request attribute under which the path info of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - INCLUDE_MAPPING
```
static final java.lang.String INCLUDE_MAPPING
```
    The name of the request attribute under which the HttpServletMapping of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - INCLUDE_SERVLET_PATH
```
static final java.lang.String INCLUDE_SERVLET_PATH
```
    The name of the request attribute under which the servlet path of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - INCLUDE_QUERY_STRING
```
static final java.lang.String INCLUDE_QUERY_STRING
```
    The name of the request attribute under which the query string of the target of an include is stored
    
    See Also:
    
    Constant Field Values
  - ERROR_EXCEPTION
```
static final java.lang.String ERROR_EXCEPTION
```
    The name of the request attribute under which the exception object is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
  - ERROR_EXCEPTION_TYPE
```
static final java.lang.String ERROR_EXCEPTION_TYPE
```
    The name of the request attribute under which the type of the exception object is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
  - ERROR_MESSAGE
```
static final java.lang.String ERROR_MESSAGE
```
    The name of the request attribute under which the exception message is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
  - ERROR_REQUEST_URI
```
static final java.lang.String ERROR_REQUEST_URI
```
    The name of the request attribute under which the request URI whose processing caused the error is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
  - ERROR_SERVLET_NAME
```
static final java.lang.String ERROR_SERVLET_NAME
```
    The name of the request attribute under which the name of the servlet in which the error occurred is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
  - ERROR_STATUS_CODE
```
static final java.lang.String ERROR_STATUS_CODE
```
    The name of the request attribute under which the response status is propagated during an error dispatch
    
    See Also:
    
    Constant Field Values
- Method Detail
  - forward
```
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.
    This method sets the dispatcher type of the given request to DispatcherType.FORWARD.
    
    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
    
    See Also:
    
    ServletRequest.getDispatcherType()
  - include
```
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.
    This method sets the dispatcher type of the given request to DispatcherType.INCLUDE.
    
    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
    
    See Also:
    
    ServletRequest.getDispatcherType()

Interface RequestDispatcher

Field Summary

Method Summary

Field Detail

FORWARD_REQUEST_URI

FORWARD_CONTEXT_PATH

FORWARD_MAPPING

FORWARD_PATH_INFO

FORWARD_SERVLET_PATH

FORWARD_QUERY_STRING

INCLUDE_REQUEST_URI

INCLUDE_CONTEXT_PATH

INCLUDE_PATH_INFO

INCLUDE_MAPPING

INCLUDE_SERVLET_PATH

INCLUDE_QUERY_STRING

ERROR_EXCEPTION

ERROR_EXCEPTION_TYPE

ERROR_MESSAGE

ERROR_REQUEST_URI

ERROR_SERVLET_NAME

ERROR_STATUS_CODE

Method Detail

forward

include