📄 dispatcherservlet.java
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/* * DispatcherServlet.java * * Created on October 10, 2002, 2:34 PM */package jwadbook.servlets;import javax.servlet.*;import javax.servlet.http.*;import java.io.*;import java.util.*;/** * * @author cai * Demo the user of request dispatcher */public class DispatcherServlet extends HttpServlet{ public void init ( ServletConfig config ) throws ServletException { super.init(config); } public void doGet ( HttpServletRequest req, HttpServletResponse resp ) throws ServletException,IOException { ServletContext context= req.getSession().getServletContext(); ServletContext context2 = context.getContext("/icwork"); PrintWriter out = resp.getWriter(); resp.setContentType("text/html"); out.println(" <HTML> "); out.println(" <HEAD>"); out.println(" <TITLE>DispatcherServlet</TITLE> "); out.println(" </HEAD> "); out.println(" <BODY BGCOLOR=white> "); out.println(" <CENTER> "); out.println(" <FONT COLOR='#009999' SIZE='4' face='Arial'> "); out.println(" <STRONG>Use RequestDispatcher to Control Servlet Collaboration</STRONG> "); out.println(" </FONT> "); out.println(" </CENTER> "); out.println(" <HR> "); String submit = req.getParameter("submit"); if (submit == null) //first time access to this servlet { out.println(" Select the dispatching method and a URL, then submit <br><br> "); out.println("<CENTER><P><H3>Please answer the questions:<H3></P>"); out.println("<FORM action='/icsamples/urldispatcher'>"); out.println("<BR> Using RequestDispatcher obtained from: <SELECT name='disptype'>"); out.println("<OPTION value='request'>request</OPTION>"); out.println("<OPTION value='context'>serveltcontext:/icsamples</OPTION>"); out.println("<OPTION value='context2'>serveltcontext:/icwork</OPTION>"); out.println("</SELECT><BR> "); out.println("<BR> Request Dispach Method: <SELECT name='dispmethod'>"); out.println("<OPTION value='include'>Include</OPTION>"); out.println("<OPTION value='forward'>Forward</OPTION>"); out.println("<OPTION value='redirect'>Redirect</OPTION>"); out.println("</SELECT> "); out.println("<BR> <BR>"); out.println("URL Location: <INPUT size='20' type='text' name='URL'><BR><BR>"); out.println("<INPUT type='submit' name='submit' value='Submit'>"); out.println(" <HR> "); out.println(" </CENTER> "); out.println(" </BODY> "); out.println(" </HTML> " ); out.flush(); } else { out.println(" Results from the DispatcherServlet <br><br> "); out.println ( "<TABLE Border=1 BGCOLOR=WHITE WIDTH='100%'> "); out.println("<TR BGCOLOR='#99cee6'> Included Resource: </TR> "); out.println("<TR><TD> "); String targetURL = req.getParameter("URL"); String disptype = req.getParameter("disptype"); if(disptype.equals("request")&&(targetURL!=null)) { RequestDispatcher desp = req.getRequestDispatcher(targetURL); dispatch(req, resp, targetURL, desp); } else if (disptype.equals("context")&&(targetURL!=null)) { RequestDispatcher desp = context.getRequestDispatcher(targetURL); dispatch(req, resp, targetURL, desp); } else if (disptype.equals("context2")&&(targetURL!=null)) { RequestDispatcher desp = context2.getRequestDispatcher(targetURL); dispatch(req, resp, targetURL, desp); }else { out.println("Wrong Dispatcher Input!"); } out.println("</TD></TR>"); out.println(" </CENTER> "); out.println(" </BODY> "); out.println(" </HTML> " ); out.flush(); } } private void dispatch (HttpServletRequest req, HttpServletResponse resp, String targetURL, RequestDispatcher desp) throws ServletException,IOException { String dispmethod = req.getParameter("dispmethod"); if (dispmethod.equals("include")) { desp.include(req, resp); } else if (dispmethod.equals("forward")) { desp.forward(req, resp); } else if (dispmethod.equals("redirect")) { resp.sendRedirect(targetURL); } //getServletContext else { } }}⌨️ 快捷键说明
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