Tomcat 10.1.19 · jakarta.servlet.http.HttpServlet · APIdia, the JavaDoc alternative

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.

Nested and Inner Type Summary

Modifier and Type	Class and Description
private static class	HttpServlet.NoBodyAsyncContextListener
private static class	HttpServlet.NoBodyOutputStream
private static class	HttpServlet.NoBodyPrintWriter
private static class	HttpServlet.NoBodyResponse
private static class	HttpServlet.TomcatHack

Field Summary

Modifier and Type	Field and Description
private volatile String	cachedAllowHeaderValue Cached value of the HTTP `Allow` header for this servlet.
private final transient Object	cachedAllowHeaderValueLock
private volatile boolean	cachedUseLegacyDoHead Cached value read from `HttpServlet#LEGACY_DO_HEAD` system property.
private static final String	HEADER_IFMODSINCE
private static final String	HEADER_LASTMOD
public static final String	LEGACY_DO_HEAD Deprecated for removal since Servlet 6.0. May be removed in a future release
private static final String	LSTRING_FILE
private static final ResourceBundle	lStrings
private static final String	METHOD_DELETE
private static final String	METHOD_GET
private static final String	METHOD_HEAD
private static final String	METHOD_OPTIONS
private static final String	METHOD_POST
private static final String	METHOD_PUT
private static final String	METHOD_TRACE
private static final List<String>	SENSITIVE_HTTP_HEADERS
private static final long	serialVersionUID Hides jakarta.servlet.GenericServlet.serialVersionUID.

Constructor Summary

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

Method Summary

Modifier and Type	Method and Description
protected void	doDelete(HttpServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, HttpServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client resp) Called by the server (via the `service` method) to allow a servlet to handle a DELETE request.
protected void	doGet(HttpServletRequest an `HttpServletRequest` object that contains the request the client has made of the servlet req, HttpServletResponse an `HttpServletResponse` object that contains the response the servlet sends to the client resp) Called by the server (via the `service` method) to allow a servlet to handle a GET request.
protected void	doHead(HttpServletRequest the request object that is passed to the servlet req, HttpServletResponse the response object that the servlet uses to return the headers to the client resp) Receives an HTTP HEAD request from the protected `service` method and handles the request.
protected void	doOptions(HttpServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, HttpServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client resp) Called by the server (via the `service` method) to allow a servlet to handle an OPTIONS request.
protected void	doPost(HttpServletRequest an `HttpServletRequest` object that contains the request the client has made of the servlet req, HttpServletResponse an `HttpServletResponse` object that contains the response the servlet sends to the client resp) Called by the server (via the `service` method) to allow a servlet to handle a POST request.
protected void	doPut(HttpServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, HttpServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client resp) Called by the server (via the `service` method) to allow a servlet to handle a PUT request.
protected void	doTrace(HttpServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, HttpServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client resp) Called by the server (via the `service` method) to allow a servlet to handle a TRACE request.
private static Method[]	getAllDeclaredMethods(Class<?> c)
private String	getCachedAllowHeaderValue()
protected long	Returns: a `long` integer specifying the time the `HttpServletRequest` object was last modified, in milliseconds since midnight, January 1, 1970 GMT, or -1 if the time is not known getLastModified(HttpServletRequest the `HttpServletRequest` object that is sent to the servlet req) Returns the time the `HttpServletRequest` object was last modified, in milliseconds since midnight January 1, 1970 GMT.
public void	init(ServletConfig the `ServletConfig` object that contains configuration information for this servlet config) Overrides jakarta.servlet.GenericServlet.init. Implements jakarta.servlet.Servlet.init. Called by the servlet container to indicate to a servlet that the servlet is being placed into service.
private boolean	Returns: (@code true} if the HTTP request header is considered sensitive and should be excluded from the response to a `TRACE` request, otherwise `false` isSensitiveHeader(String the name of the HTTP request header to test headerName) Is the provided HTTP request header considered sensitive and therefore should be excluded from the response to a `TRACE` request?
private void	maybeSetLastModified(HttpServletResponse resp, long lastModified)
private void	sendMethodNotAllowed(HttpServletRequest req, HttpServletResponse resp, String msg)
protected void	service(HttpServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, HttpServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client resp) Receives standard HTTP requests from the public `service` method and dispatches them to the `do`Method methods defined in this class.
public void	service(ServletRequest the `HttpServletRequest` object that contains the request the client made of the servlet req, ServletResponse the `HttpServletResponse` object that contains the response the servlet returns to the client res) Implements abstract jakarta.servlet.GenericServlet.service. Implements jakarta.servlet.Servlet.service. Dispatches client requests to the protected `service` method.

Inherited from jakarta.servlet.GenericServlet:: destroy getInitParameter getInitParameterNames getServletConfig getServletContext getServletInfo getServletName init log log

public abstract Class HttpServlet

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary