Package javax.servlet.http

Class HttpServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

Direct Known Subclasses:

AbstractAuthenticationFormServlet, AbstractWebConsolePlugin, AbstractWebdavServlet, DefaultServlet, HttpJspBase, Invoker, NoJspServlet, ServletHandler.Default404Servlet, StatisticsServlet, ViewStatusMessagesServletBase

public abstract class HttpServlet
extends GenericServlet

Provides an abstract class to be subclassed to create an HTTP servlet suitable for a Web site. A subclass of HttpServlet must override at least one method, usually one of these:

• doGet, if the servlet supports HTTP GET requests
• doPost, for HTTP POST requests
• doPut, for HTTP PUT requests
• doDelete, for HTTP DELETE requests
• init and destroy, to manage resources that are held for the life of the servlet
• getServletInfo, which the servlet uses to provide information about itself

There's almost no reason to override the service method. service handles standard HTTP requests by dispatching them to the handler methods for each HTTP request type (the doMethod methods listed above).

Likewise, there's almost no reason to override the doOptions and doTrace methods.

Servlets typically run on multithreaded servers, so be aware that a servlet must handle concurrent requests and be careful to synchronize access to shared resources. Shared resources include in-memory data such as instance or class variables and external objects such as files, database connections, and network connections. See the Java Tutorial on Multithreaded Programming for more information on handling multiple threads in a Java program.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
HttpServlet()	Does nothing, because this is an abstract class.

Method Summary

Modifier and Type	Method	Description
void	service(ServletRequest req, ServletResponse res)	Dispatches client requests to the protected service method.

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

HttpServlet

public HttpServlet()

Does nothing, because this is an abstract class.

Method Details

service

public void service(ServletRequest req,
 ServletResponse res)
             throws ServletException,
IOException

Dispatches client requests to the protected service method. There's no need to override this method.

Specified by:

service in interface Servlet

Specified by:

service in class GenericServlet

Parameters:

req - the HttpServletRequest object that contains the request the client made of the servlet

res - the HttpServletResponse object that contains the response the servlet returns to the client

Throws:

IOException - if an input or output error occurs while the servlet is handling the HTTP request

ServletException - if the HTTP request cannot be handled

See Also:

• Servlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)