Class GenericServlet

java.lang.Object
javax.servlet.GenericServlet
All Implemented Interfaces:
Serializable, Servlet, ServletConfig
Direct Known Subclasses:
HttpServlet
public abstract class GenericServlet extends Object implements Servlet, ServletConfig, Serializable
Abstract base class for all servlets.
Since:
Servlet API 1.0
Version:
Servlet API 2.2
See Also:

  • Constructor Details

    • GenericServlet

      public GenericServlet()
      Does nothing.
      Since:
      Servlet API 1.0

  • Method Details

    • init

      public void init(ServletConfig servletConfig) throws ServletException
      Initializes the servlet. Called by the server exactly once during the lifetime of the servlet. This method can be used to setup resources (connections to a database for example) for this servlet.

      This version saves the ServletConfig and calls init(). This means that a servlet can just override init(). Note that if a servlet overrides this method it should call super.init(servletConfig) otherwise the other methods in GenericServlet are not garanteed to work.

      Specified by:
      init in interface Servlet
      Parameters:
      servletConfig - This servlet configuration class
      Throws:
      ServletException - If an error occurs
      Since:
      Servlet API 1.0
      See Also:

    • init

      public void init() throws ServletException
      Automatically called by init(ServletConfig servletConfig). This version does nothing.
      Throws:
      ServletException - If an error occurs
      Since:
      Servlet API 2.1

    • getServletContext

      public ServletContext getServletContext()
      Returns the servlets context
      Specified by:
      getServletContext in interface ServletConfig
      Returns:
      The context
      Since:
      Servlet API 1.0

    • getInitParameter

      public String getInitParameter(String name)
      Gets a servlet's initialization parameter
      Specified by:
      getInitParameter in interface ServletConfig
      Parameters:
      name - the name of the wanted parameter
      Returns:
      the value of the wanted parameter. null if the named parameter is not present.
      Since:
      Servlet API 1.0

    • getInitParameterNames

      public Enumeration getInitParameterNames()
      Gets all the initialization parameters
      Specified by:
      getInitParameterNames in interface ServletConfig
      Returns:
      an Enumeration of all the parameters
      Since:
      Servlet API 1.0

    • log

      public void log(String message)
      Writes the class name and a message to the log. Calls getServletContext().log().
      Parameters:
      message - the message to write
      Since:
      Servlet API 1.0

    • log

      public void log(String message, Throwable th)
      Writes the class name, a message and a stack trace to the log. Calls getServletContext().log().
      Parameters:
      message - the message to write
      th - the object that was thrown to cause this log
      Since:
      Servlet API 2.1

    • getServletInfo

      public String getServletInfo()
      The servlet programmer can put other additional info (version number, etc) here.

      The Servlet 2.1 Spec says that this should return an empty string. The Servlet 2.1 API says that this should return null unless overridden. This version returns the servlet's class name which seems more usefull.

      Specified by:
      getServletInfo in interface Servlet
      Returns:
      The String holding the information
      Since:
      Servlet API 1.0

    • getServletConfig

      public ServletConfig getServletConfig()
      Gets the servlet servletConfig class
      Specified by:
      getServletConfig in interface Servlet
      Returns:
      The servletConfig class
      Since:
      Servlet API 1.0

    • service

      public abstract void service(ServletRequest request, ServletResponse response) throws ServletException, IOException
      Called by the server every time it wants the servlet to handle a request.
      Specified by:
      service in interface Servlet
      Parameters:
      request - all the request information
      response - class to write all the response data to
      Throws:
      ServletException - If an error occurs
      IOException - If an error occurs
      Since:
      Servlet API 1.0
      See Also:

    • destroy

      public void destroy()
      Called by the server when it no longer needs the servlet. The servlet programmer should use this method to free all the resources the servlet is holding.

      This version does nothing because it has nothing to clean up.

      Note that the the 2.1 Spec says that this should do nothing, but the 2.1 API Doc says that it logs the destroy action.

      Specified by:
      destroy in interface Servlet
      Since:
      Servlet API 1.0

    • getServletName

      public String getServletName()
      Gets you the name of this servlet's instance. Calls its servletConfig's getServletName.
      Specified by:
      getServletName in interface ServletConfig