public abstract class GenericServlet extends java.lang.Object implements Servlet, ServletConfig, java.io.Serializable
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.
| Constructor and Description |
|---|
GenericServlet()
Does nothing.
|
| Modifier and Type | Method and Description |
|---|---|
void |
destroy()
Called by the servlet container to indicate to a servlet that the servlet
is being taken out of service.
|
java.lang.String |
getInitParameter(java.lang.String name)
Returns a
String containing the value of the named
initialization parameter, or null if the parameter does not
exist. |
java.util.Enumeration<java.lang.String> |
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. |
ServletConfig |
getServletConfig()
Returns this servlet's
ServletConfig object. |
ServletContext |
getServletContext()
Returns a reference to the
ServletContext in which this servlet
is running. |
java.lang.String |
getServletInfo()
Returns information about the servlet, such as author, version, and
copyright.
|
java.lang.String |
getServletName()
Returns the name of this servlet instance.
|
void |
init()
A convenience method which can be overridden so that there's no need to
call
super.init(config). |
void |
init(ServletConfig config)
Called by the servlet container to indicate to a servlet that the servlet
is being placed into service.
|
void |
log(java.lang.String message)
Writes the specified message to a servlet log file, prepended by the
servlet's name.
|
void |
log(java.lang.String message,
java.lang.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. |
abstract void |
service(ServletRequest req,
ServletResponse res)
Called by the servlet container to allow the servlet to respond to a
request.
|
public GenericServlet()
init methods.public void destroy()
Servlet.destroy().public java.lang.String getInitParameter(java.lang.String name)
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.
getInitParameter in interface ServletConfigname - a String specifying the name of the
initialization parameterString containing the value of the
initialization parameterpublic java.util.Enumeration<java.lang.String> getInitParameterNames()
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.
getInitParameterNames in interface ServletConfigString objects
containing the names of the servlet's initialization parameterspublic ServletConfig getServletConfig()
ServletConfig object.getServletConfig in interface ServletServletConfig object that
initialized this servletServlet.init(javax.servlet.ServletConfig)public ServletContext getServletContext()
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.
getServletContext in interface ServletConfigServletContext object passed to
this servlet by the init methodServletContextpublic java.lang.String getServletInfo()
Servlet.getServletInfo().getServletInfo in interface Servletpublic void init(ServletConfig config) throws ServletException
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).
init in interface Servletconfig - the ServletConfig object that contains
configuration information for this servletServletException - if an exception occurs that interrupts the servlet's
normal operationUnavailableExceptionpublic void init()
throws ServletException
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().
ServletException - if an exception occurs that interrupts the servlet's
normal operationpublic void log(java.lang.String message)
ServletContext.log(String).message - a String specifying the message to be written to
the log filepublic void log(java.lang.String message,
java.lang.Throwable t)
Throwable exception to the servlet log file, prepended by
the servlet's name. See ServletContext.log(String, Throwable).message - a String that describes the error or exceptiont - the java.lang.Throwable error or exceptionpublic abstract void service(ServletRequest req, ServletResponse res) throws ServletException, java.io.IOException
Servlet.service(javax.servlet.ServletRequest, javax.servlet.ServletResponse).
This method is declared abstract so subclasses, such as
HttpServlet, must override it.
service in interface Servletreq - the ServletRequest object that contains the
client's requestres - the ServletResponse object that will contain the
servlet's responseServletException - if an exception occurs that interferes with the servlet's
normal operation occurredjava.io.IOException - if an input or output exception occurspublic java.lang.String getServletName()
ServletConfig.getServletName().getServletName in interface ServletConfigCopyright © 2000-2022 Apache Software Foundation. All Rights Reserved.