--- /dev/null
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package javax.servlet;
+
+import java.io.IOException;
+import java.util.Enumeration;
+
+/**
+ * Defines a generic, protocol-independent servlet. To write an HTTP servlet for
+ * use on the Web, extend {@link javax.servlet.http.HttpServlet} instead.
+ * <p>
+ * <code>GenericServlet</code> implements the <code>Servlet</code> and
+ * <code>ServletConfig</code> interfaces. <code>GenericServlet</code> may be
+ * directly extended by a servlet, although it's more common to extend a
+ * protocol-specific subclass such as <code>HttpServlet</code>.
+ * <p>
+ * <code>GenericServlet</code> makes writing servlets easier. It provides simple
+ * versions of the lifecycle methods <code>init</code> and <code>destroy</code>
+ * and of the methods in the <code>ServletConfig</code> interface.
+ * <code>GenericServlet</code> also implements the <code>log</code> method,
+ * declared in the <code>ServletContext</code> interface.
+ * <p>
+ * To write a generic servlet, you need only override the abstract
+ * <code>service</code> method.
+ */
+public abstract class GenericServlet implements Servlet, ServletConfig,
+ java.io.Serializable {
+
+ private static final long serialVersionUID = 1L;
+
+ private transient ServletConfig config;
+
+ /**
+ * Does nothing. All of the servlet initialization is done by one of the
+ * <code>init</code> methods.
+ */
+ public GenericServlet() {
+ // NOOP
+ }
+
+ /**
+ * Called by the servlet container to indicate to a servlet that the servlet
+ * is being taken out of service. See {@link Servlet#destroy}.
+ */
+ @Override
+ public void destroy() {
+ // NOOP by default
+ }
+
+ /**
+ * Returns a <code>String</code> containing the value of the named
+ * initialization parameter, or <code>null</code> if the parameter does not
+ * exist. See {@link ServletConfig#getInitParameter}.
+ * <p>
+ * This method is supplied for convenience. It gets the value of the named
+ * parameter from the servlet's <code>ServletConfig</code> object.
+ *
+ * @param name
+ * a <code>String</code> specifying the name of the
+ * initialization parameter
+ * @return String a <code>String</code> containing the value of the
+ * initialization parameter
+ */
+ @Override
+ public String getInitParameter(String name) {
+ return getServletConfig().getInitParameter(name);
+ }
+
+ /**
+ * Returns the names of the servlet's initialization parameters as an
+ * <code>Enumeration</code> of <code>String</code> objects, or an empty
+ * <code>Enumeration</code> if the servlet has no initialization parameters.
+ * See {@link ServletConfig#getInitParameterNames}.
+ * <p>
+ * This method is supplied for convenience. It gets the parameter names from
+ * the servlet's <code>ServletConfig</code> object.
+ *
+ * @return Enumeration an enumeration of <code>String</code> objects
+ * containing the names of the servlet's initialization parameters
+ */
+ @Override
+ public Enumeration<String> getInitParameterNames() {
+ return getServletConfig().getInitParameterNames();
+ }
+
+ /**
+ * Returns this servlet's {@link ServletConfig} object.
+ *
+ * @return ServletConfig the <code>ServletConfig</code> object that
+ * initialized this servlet
+ */
+ @Override
+ public ServletConfig getServletConfig() {
+ return config;
+ }
+
+ /**
+ * Returns a reference to the {@link ServletContext} in which this servlet
+ * is running. See {@link ServletConfig#getServletContext}.
+ * <p>
+ * This method is supplied for convenience. It gets the context from the
+ * servlet's <code>ServletConfig</code> object.
+ *
+ * @return ServletContext the <code>ServletContext</code> object passed to
+ * this servlet by the <code>init</code> method
+ */
+ @Override
+ public ServletContext getServletContext() {
+ return getServletConfig().getServletContext();
+ }
+
+ /**
+ * 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
+ * {@link Servlet#getServletInfo}.
+ *
+ * @return String information about this servlet, by default an empty string
+ */
+ @Override
+ public String getServletInfo() {
+ return "";
+ }
+
+ /**
+ * Called by the servlet container to indicate to a servlet that the servlet
+ * is being placed into service. See {@link Servlet#init}.
+ * <p>
+ * This implementation stores the {@link ServletConfig} object it receives
+ * from the servlet container for later use. When overriding this form of
+ * the method, call <code>super.init(config)</code>.
+ *
+ * @param config
+ * the <code>ServletConfig</code> object that contains
+ * configuration information for this servlet
+ * @exception ServletException
+ * if an exception occurs that interrupts the servlet's
+ * normal operation
+ * @see UnavailableException
+ */
+ @Override
+ public void init(ServletConfig config) throws ServletException {
+ this.config = config;
+ this.init();
+ }
+
+ /**
+ * A convenience method which can be overridden so that there's no need to
+ * call <code>super.init(config)</code>.
+ * <p>
+ * Instead of overriding {@link #init(ServletConfig)}, simply override this
+ * method and it will be called by
+ * <code>GenericServlet.init(ServletConfig config)</code>. The
+ * <code>ServletConfig</code> object can still be retrieved via
+ * {@link #getServletConfig}.
+ *
+ * @exception ServletException
+ * if an exception occurs that interrupts the servlet's
+ * normal operation
+ */
+ public void init() throws ServletException {
+ // NOOP by default
+ }
+
+ /**
+ * Writes the specified message to a servlet log file, prepended by the
+ * servlet's name. See {@link ServletContext#log(String)}.
+ *
+ * @param msg
+ * a <code>String</code> specifying the message to be written to
+ * the log file
+ */
+ public void log(String msg) {
+ getServletContext().log(getServletName() + ": " + msg);
+ }
+
+ /**
+ * Writes an explanatory message and a stack trace for a given
+ * <code>Throwable</code> exception to the servlet log file, prepended by
+ * the servlet's name. See {@link ServletContext#log(String, Throwable)}.
+ *
+ * @param message
+ * a <code>String</code> that describes the error or exception
+ * @param t
+ * the <code>java.lang.Throwable</code> error or exception
+ */
+ public void log(String message, Throwable t) {
+ getServletContext().log(getServletName() + ": " + message, t);
+ }
+
+ /**
+ * Called by the servlet container to allow the servlet to respond to a
+ * request. See {@link Servlet#service}.
+ * <p>
+ * This method is declared abstract so subclasses, such as
+ * <code>HttpServlet</code>, must override it.
+ *
+ * @param req
+ * the <code>ServletRequest</code> object that contains the
+ * client's request
+ * @param res
+ * the <code>ServletResponse</code> object that will contain the
+ * servlet's response
+ * @exception ServletException
+ * if an exception occurs that interferes with the servlet's
+ * normal operation occurred
+ * @exception IOException
+ * if an input or output exception occurs
+ */
+ @Override
+ public abstract void service(ServletRequest req, ServletResponse res)
+ throws ServletException, IOException;
+
+ /**
+ * Returns the name of this servlet instance. See
+ * {@link ServletConfig#getServletName}.
+ *
+ * @return the name of this servlet instance
+ */
+ @Override
+ public String getServletName() {
+ return config.getServletName();
+ }
+}
projects / gigi.git / blobdiff