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java.lang.Objectjavax.servlet.GenericServlet
@TransactionType(value=NOT_SUPPORTED) public abstract class GenericServlet
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.
| Constructor Summary | |
|---|---|
GenericServlet()
Does nothing. |
|
| Method Summary | |
|---|---|
void |
destroy()
Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. |
String |
getInitParameter(String name)
Returns a String containing the value of the named
initialization parameter, or null if the parameter does
not exist. |
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. |
ServletConfig |
getServletConfig()
Returns this servlet's ServletConfig object. |
ServletContext |
getServletContext()
Returns a reference to the ServletContext in which this servlet
is running. |
String |
getServletInfo()
Returns information about the servlet, such as author, version, and copyright. |
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(String msg)
Writes the specified message to a servlet log file, prepended by the servlet's name. |
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. |
abstract void |
service(ServletRequest req,
ServletResponse res)
Called by the servlet container to allow the servlet to respond to a request. |
| Methods inherited from class java.lang.Object |
|---|
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public GenericServlet()
init methods.
| Method Detail |
|---|
public void destroy()
Servlet.destroy().
destroy in interface Servletpublic String getInitParameter(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 parameter
String containing the value of the
initialization parameterpublic Enumeration 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 String getServletInfo()
Servlet.getServletInfo().
getServletInfo in interface Servlet
public 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 servlet
ServletException - if an exception occurs that interrupts the servlet's
normal operationUnavailableException
public 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(String msg)
ServletContext.log(String).
msg - a String specifying the message to be written
to the log file
public void log(String message,
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 exception
public abstract void service(ServletRequest req,
ServletResponse res)
throws ServletException,
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 response
ServletException - if an exception occurs that interferes with the servlet's
normal operation occurred
IOException - if an input or output exception occurspublic String getServletName()
ServletConfig.getServletName().
getServletName in interface ServletConfig
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