GenericServlet (Java EE 5 SDK)

javax.servlet Class GenericServlet

java.lang.Object
  javax.servlet.GenericServlet

所有已实现的接口:

Serializable, Servlet, ServletConfig

直接已知子类:

HttpServlet

public abstract class GenericServlet

extends Object

implements Servlet, ServletConfig, Serializable

Defines a generic, protocol-independent servlet. To write an HTTP servlet for use on the Web, extend HttpServlet instead.

GenericServlet implements the Servlet and ServletConfig interfaces. GenericServlet may be directly extended by a servlet, although it's more common to extend a protocol-specific subclass such as HttpServlet.

GenericServlet makes writing servlets easier. It provides simple versions of the lifecycle methods init and destroy and of the methods in the ServletConfig interface. GenericServlet also implements the log method, declared in the ServletContext interface.

To write a generic servlet, you need only override the abstract service method.

作者:

Various

另请参见:

Serialized Form

GenericServlet

public GenericServlet()

Does nothing. All of the servlet initialization is done by one of the init methods.

destroy

public void destroy()

Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. See Servlet.destroy().

规范说明:

destroy in interface Servlet

getInitParameter

public String getInitParameter(String name)

Returns a String containing the value of the named initialization parameter, or null if the parameter does not exist. See ServletConfig.getInitParameter(java.lang.String).

This method is supplied for convenience. It gets the value of the named parameter from the servlet's ServletConfig object.

规范说明:

getInitParameter in interface ServletConfig

参数:

name - a String specifying the name of the initialization parameter

返回:

String a String containing the value of the initialization parameter

getInitParameterNames

public Enumeration getInitParameterNames()

Returns the names of the servlet's initialization parameters as an Enumeration of String objects, or an empty Enumeration if the servlet has no initialization parameters. See ServletConfig.getInitParameterNames().

This method is supplied for convenience. It gets the parameter names from the servlet's ServletConfig object.

规范说明:

getInitParameterNames in interface ServletConfig

返回:

Enumeration an enumeration of String objects containing the names of the servlet's initialization parameters

getServletConfig

public ServletConfig getServletConfig()

Returns this servlet's ServletConfig object.

规范说明:

getServletConfig in interface Servlet

返回:

ServletConfig the ServletConfig object that initialized this servlet

另请参见:

Servlet.init(javax.servlet.ServletConfig)

getServletContext

public ServletContext getServletContext()

Returns a reference to the ServletContext in which this servlet is running. See ServletConfig.getServletContext().

This method is supplied for convenience. It gets the context from the servlet's ServletConfig object.

规范说明:

getServletContext in interface ServletConfig

返回:

ServletContext the ServletContext object passed to this servlet by the init method

另请参见:

ServletContext

getServletInfo

public String getServletInfo()

Returns information about the servlet, such as author, version, and copyright. By default, this method returns an empty string. Override this method to have it return a meaningful value. See Servlet.getServletInfo().

规范说明:

getServletInfo in interface Servlet

返回:

String information about this servlet, by default an empty string

init

public void init(ServletConfig config)
          throws ServletException

Called by the servlet container to indicate to a servlet that the servlet is being placed into service. See Servlet.init(javax.servlet.ServletConfig).

This implementation stores the ServletConfig object it receives from the servlet container for later use. When overriding this form of the method, call super.init(config).

规范说明:

init in interface Servlet

参数:

config - the ServletConfig object that contains configutation information for this servlet

抛出异常:

ServletException - if an exception occurs that interrupts the servlet's normal operation

另请参见:

UnavailableException

init

public void init()
          throws ServletException

A convenience method which can be overridden so that there's no need to call super.init(config).

Instead of overriding init(ServletConfig), simply override this method and it will be called by GenericServlet.init(ServletConfig config). The ServletConfig object can still be retrieved via getServletConfig().

抛出异常:

ServletException - if an exception occurs that interrupts the servlet's normal operation

log

public void log(String msg)

Writes the specified message to a servlet log file, prepended by the servlet's name. See ServletContext.log(String).

参数:

msg - a String specifying the message to be written to the log file

log

public void log(String message,
                Throwable t)

Writes an explanatory message and a stack trace for a given Throwable exception to the servlet log file, prepended by the servlet's name. See ServletContext.log(String, Throwable).

参数:

message - a String that describes the error or exception

t - the java.lang.Throwable error or exception

service

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

Called by the servlet container to allow the servlet to respond to a request. See Servlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse).

This method is declared abstract so subclasses, such as HttpServlet, must override it.

规范说明:

service in interface Servlet

参数:

req - the ServletRequest object that contains the client's request

res - the ServletResponse object that will contain the servlet's response

抛出异常:

ServletException - if an exception occurs that interferes with the servlet's normal operation occurred

IOException - if an input or output exception occurs

getServletName

public String getServletName()

Returns the name of this servlet instance. See ServletConfig.getServletName().

规范说明:

getServletName in interface ServletConfig

返回:

the name of this servlet instance

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