servlet/jsp随记

public interface Servlet { ???...... ???public void init(ServletConfig config) throws ServletException; ???public ServletConfig getServletConfig(); ???public void service(ServletRequest req, ServletResponse res) ???????????throws ServletException, IOException; ???public String getServletInfo(); ???public void destroy(); ???......}

public interface RequestDispatcher { ???...... ??/** ????* Forwards a request from ????* a servlet to another resource (servlet, JSP file, or ????* HTML file) on the server. This method allows ????* one servlet to do preliminary processing of ????* a request and another resource to generate ????* the response. ????* ????* <p>For a <code>RequestDispatcher</code> obtained via ?????* <code>getRequestDispatcher()</code>, the <code>ServletRequest</code> ?????* object has its path elements and parameters adjusted to match ????* the path of the target resource. ????* ????* <p><code>forward</code> should be called before the response has been ?????* committed to the client (before response body output has been flushed). ?????* If the response already has been committed, this method throws ????* an <code>IllegalStateException</code>. ????* Uncommitted output in the response buffer is automatically cleared ?????* before the forward. ????* ????* <p>The request and response parameters must be either the same ????* objects as were passed to the calling servlet‘s service method or be ????* subclasses of the {@link ServletRequestWrapper} or ????* {@link ServletResponseWrapper} classes ????* that wrap them. ????* ????* <p>This method sets the dispatcher type of the given request to ????* <code>DispatcherType.FORWARD</code>. ????* ????* @param request a {@link ServletRequest} object that represents the ????* request the client makes of the servlet ????* ????* @param response a {@link ServletResponse} object that represents ????* the response the servlet returns to the client ????* ????* @throws ServletException if the target resource throws this exception ????* ????* @throws IOException if the target resource throws this exception ????* ????* @throws IllegalStateException if the response was already committed ????* ????* @see ServletRequest#getDispatcherType ????*/ ???public void forward(ServletRequest request, ServletResponse response) ???????throws ServletException, IOException; ???/** ????* ????* Includes the content of a resource (servlet, JSP page, ????* HTML file) in the response. In essence, this method enables ?????* programmatic server-side includes. ????* ????* <p>The {@link ServletResponse} object has its path elements ????* and parameters remain unchanged from the caller‘s. The included ????* servlet cannot change the response status code or set headers; ????* any attempt to make a change is ignored. ????* ????* <p>The request and response parameters must be either the same ????* objects as were passed to the calling servlet‘s service method or be ????* subclasses of the {@link ServletRequestWrapper} or ????* {@link ServletResponseWrapper} classes that wrap them. ????* ????* <p>This method sets the dispatcher type of the given request to ????* <code>DispatcherType.INCLUDE</code>. ????* ????* @param request a {@link ServletRequest} object that contains the ????* client‘s request ????* ????* @param response a {@link ServletResponse} object that contains the ????* servlet‘s response ????* ????* @throws ServletException if the included resource throws this ????* exception ????* ????* @throws IOException if the included resource throws this exception ????* ????* @see ServletRequest#getDispatcherType ????*/ ???public void include(ServletRequest request, ServletResponse response) ???????throws ServletException, IOException; ???......}

- request：封装客户端的请求，其中包含来自GET或POST请求的参数； - response：封装服务器对客户端的响应； - pageContext：通过该对象可以获取其他对象； - session：封装用户会话的对象； - application：封装服务器运行环境的对象； - out：输出服务器响应的输出流对象； - config：Web应用的配置对象； - page：JSP页面本身（相当于Java程序中的this）； - exception：封装页面抛出异常的对象