Interface RequestDispatcher
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.
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when custom error-handling servlet or JSP page is invoked.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theforward(ServletRequest, ServletResponse)method is called.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name.static final StringThe name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. -
Method Summary
Modifier and TypeMethodDescriptionvoidforward(ServletRequest request, ServletResponse response) Forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server.voidinclude(ServletRequest request, ServletResponse response) Includes the content of a resource (servlet, JSP page, HTML file) in the response.
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Field Details
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FORWARD_REQUEST_URI
The name of the request attribute that should be set by the container when theforward(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
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FORWARD_CONTEXT_PATH
The name of the request attribute that should be set by the container when theforward(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
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FORWARD_MAPPING
The name of the request attribute that should be set by the container when theforward(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 4.0
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FORWARD_PATH_INFO
The name of the request attribute that should be set by the container when theforward(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
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FORWARD_SERVLET_PATH
The name of the request attribute that should be set by the container when theforward(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
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FORWARD_QUERY_STRING
The name of the request attribute that should be set by the container when theforward(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
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INCLUDE_REQUEST_URI
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 3.0
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INCLUDE_CONTEXT_PATH
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 3.0
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INCLUDE_PATH_INFO
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 3.0
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INCLUDE_MAPPING
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 4.0
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INCLUDE_SERVLET_PATH
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 3.0
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INCLUDE_QUERY_STRING
The name of the request attribute that should be set by the container when theinclude(ServletRequest, ServletResponse)method is called on theRequestDispatcherobtained by a path and not by a name. It provides information on the path that was used to obtain theRequestDispatcherinstance for this include call. See the chapter "Included Request Parameters" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typejava.lang.Throwable. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typejava.lang.Class. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typeString. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typeString. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typeString. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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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 typejava.lang.Integer. See the chapter "Error Handling" in the Servlet Specification for details.- Since:
- Servlet 3.0
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Method Details
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forward
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
RequestDispatcherobtained viagetRequestDispatcher(), theServletRequestobject has its path elements and parameters adjusted to match the path of the target resource.forwardshould 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 anIllegalStateException. 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
ServletRequestWrapperorServletResponseWrapperclasses that wrap them.- Parameters:
request- aServletRequestobject that represents the request the client makes of the servletresponse- aServletResponseobject that represents the response the servlet returns to the client- Throws:
ServletException- if the target resource throws this exceptionIOException- if the target resource throws this exceptionIllegalStateException- if the response was already committed
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include
Includes the content of a resource (servlet, JSP page, HTML file) in the response. In essence, this method enables programmatic server-side includes.The
ServletResponseobject 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
ServletRequestWrapperorServletResponseWrapperclasses that wrap them.- Parameters:
request- aServletRequestobject that contains the client's requestresponse- aServletResponseobject that contains the servlet's response- Throws:
ServletException- if the included resource throws this exceptionIOException- if the included resource throws this exception
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