RequestDispatcher (Apache Tomcat 7.0.109 API Documentation)

```
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.

Author:

Various

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 String`	`ERROR_EXCEPTION` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`ERROR_EXCEPTION_TYPE` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`ERROR_MESSAGE` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`ERROR_REQUEST_URI` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`ERROR_SERVLET_NAME` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`ERROR_STATUS_CODE` The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.
`static String`	`FORWARD_CONTEXT_PATH` The name of the request attribute that should be set by the container when the `forward(ServletRequest, ServletResponse)` method is called.
`static String`	`FORWARD_PATH_INFO` The name of the request attribute that should be set by the container when the `forward(ServletRequest, ServletResponse)` method is called.
`static String`	`FORWARD_QUERY_STRING` The name of the request attribute that should be set by the container when the `forward(ServletRequest, ServletResponse)` method is called.
`static String`	`FORWARD_REQUEST_URI` The name of the request attribute that should be set by the container when the `forward(ServletRequest, ServletResponse)` method is called.
`static String`	`FORWARD_SERVLET_PATH` The name of the request attribute that should be set by the container when the `forward(ServletRequest, ServletResponse)` method is called.
`static String`	`INCLUDE_CONTEXT_PATH` The name of the request attribute that should be set by the container when the `include(ServletRequest, ServletResponse)` method is called on the `RequestDispatcher` obtained by a path and not by a name.
`static String`	`INCLUDE_PATH_INFO` The name of the request attribute that should be set by the container when the `include(ServletRequest, ServletResponse)` method is called on the `RequestDispatcher` obtained by a path and not by a name.
`static String`	`INCLUDE_QUERY_STRING` The name of the request attribute that should be set by the container when the `include(ServletRequest, ServletResponse)` method is called on the `RequestDispatcher` obtained by a path and not by a name.
`static String`	`INCLUDE_REQUEST_URI` The name of the request attribute that should be set by the container when the `include(ServletRequest, ServletResponse)` method is called on the `RequestDispatcher` obtained by a path and not by a name.
`static String`	`INCLUDE_SERVLET_PATH` The name of the request attribute that should be set by the container when the `include(ServletRequest, ServletResponse)` method is called on the `RequestDispatcher` obtained by a path and not by a name.

Method Summary

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
  - ERROR_EXCEPTION
```
static final String ERROR_EXCEPTION
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Throwable. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - ERROR_EXCEPTION_TYPE
```
static final String ERROR_EXCEPTION_TYPE
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Class. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - ERROR_MESSAGE
```
static final String ERROR_MESSAGE
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.String. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - ERROR_REQUEST_URI
```
static final String ERROR_REQUEST_URI
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.String. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - ERROR_SERVLET_NAME
```
static final String ERROR_SERVLET_NAME
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.String. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - ERROR_STATUS_CODE
```
static final String ERROR_STATUS_CODE
```
    The name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked. The value of the attribute is of type java.lang.Integer. See the chapter "Error Handling" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - FORWARD_CONTEXT_PATH
```
static final String FORWARD_CONTEXT_PATH
```
    The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - FORWARD_PATH_INFO
```
static final String FORWARD_PATH_INFO
```
    The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - FORWARD_QUERY_STRING
```
static final String FORWARD_QUERY_STRING
```
    The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - FORWARD_REQUEST_URI
```
static final String FORWARD_REQUEST_URI
```
    The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - FORWARD_SERVLET_PATH
```
static final String FORWARD_SERVLET_PATH
```
    The name of the request attribute that should be set by the container when the forward(ServletRequest, ServletResponse) method is called. It provides the original value of a path-related property of the request. See the chapter "Forwarded Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - INCLUDE_CONTEXT_PATH
```
static final String INCLUDE_CONTEXT_PATH
```
    The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - INCLUDE_PATH_INFO
```
static final String INCLUDE_PATH_INFO
```
    The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - INCLUDE_QUERY_STRING
```
static final String INCLUDE_QUERY_STRING
```
    The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - INCLUDE_REQUEST_URI
```
static final String INCLUDE_REQUEST_URI
```
    The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
  - INCLUDE_SERVLET_PATH
```
static final String INCLUDE_SERVLET_PATH
```
    The name of the request attribute that should be set by the container when the include(ServletRequest, ServletResponse) method is called on the RequestDispatcher obtained by a path and not by a name. It provides information on the path that was used to obtain the RequestDispatcher instance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.
    
    Since:
    
    Servlet 3.0
    
    See Also:
    Constant Field Values
- Method Detail
  - forward
```
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 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
    
    IOException - if the target resource throws this exception
    
    IllegalStateException - if the response was already committed
  - include
```
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 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
    
    IOException - if the included resource throws this exception

Interface RequestDispatcher

Field Summary

Method Summary

Field Detail

ERROR_EXCEPTION

ERROR_EXCEPTION_TYPE

ERROR_MESSAGE

ERROR_REQUEST_URI

ERROR_SERVLET_NAME

ERROR_STATUS_CODE

FORWARD_CONTEXT_PATH

FORWARD_PATH_INFO

FORWARD_QUERY_STRING

FORWARD_REQUEST_URI

FORWARD_SERVLET_PATH

INCLUDE_CONTEXT_PATH

INCLUDE_PATH_INFO

INCLUDE_QUERY_STRING

INCLUDE_REQUEST_URI

INCLUDE_SERVLET_PATH

Method Detail

forward

include