在web程序中,经常是由多个Servlet来完成请求.RequestDispatcher接口就是为了多个Servlet之间的调整而实现的.该接口可以用httpSerbletRequest的getRequestDispatcher()方法取得.调用时指定跳转的URL地址即可完成跳转动作.RequestDispatcher接口有两种方法实现跳转
一.include方法
本示例不需要前台页面,直接通过地址访问.
IncludeMethod.java代码
1 package com.gys;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5
6 import javax.servlet.RequestDispatcher;
7 import javax.servlet.ServletException;
8 import javax.servlet.annotation.WebServlet;
9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12
13 @WebServlet(
14 name="demo",
15 urlPatterns={"/include"}
16 )
17 public class IncludeMethod extends HttpServlet{
18 @Override
19 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
20 throws ServletException, IOException {
21 doGet(req, resp);
22 }
23 @Override
24 protected void doGet(HttpServletRequest request, HttpServletResponse response)
25 throws ServletException, IOException {
26 response.setContentType("text/html;charset=utf-8");
27 PrintWriter out=response.getWriter();
28 out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
29 out.println("<HTML>");
30 out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
31 out.println(" <BODY>");
32 out.print(" <h1>第一个servlet</h1>");
33 RequestDispatcher dispatcher=request.getRequestDispatcher("/includeSecond");
34 dispatcher.include(request, response);
35 out.println(" </BODY>");
36 out.println("</HTML>");
37 out.flush();
38 out.close();
39 }
40 }
IncludeMethod2.java
1 package com.gys;
2
3 import java.io.IOException;
4 import java.io.PrintWriter;
5
6 import javax.servlet.ServletException;
7 import javax.servlet.annotation.WebServlet;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11
12
13 @WebServlet(
14 name="include2",
15 urlPatterns={"/includeSecond"}
16 )
17 public class IncludeMethod2 extends HttpServlet{
18 @Override
19 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
20 throws ServletException, IOException {
21 doGet(req, resp);
22 }
23 @Override
24 protected void doGet(HttpServletRequest request, HttpServletResponse response)
25 throws ServletException, IOException {
26 response.setContentType("text/html;charset=utf-8");
27 PrintWriter out=response.getWriter();
28 out.println("这是第二个servlet(被包涵在第一个servlet里面)");
29 }
30 }
测试结果:
二.forward()
forwardMethod.java代码
1 package com.gys2;
2
3 import java.io.IOException;
4
5 import javax.servlet.ServletException;
6 import javax.servlet.annotation.WebServlet;
7 import javax.servlet.http.HttpServlet;
8 import javax.servlet.http.HttpServletRequest;
9 import javax.servlet.http.HttpServletResponse;
10
11 @WebServlet(
12 name="forwardMethod",
13 urlPatterns={"/test"}
14 )
15
16 public class forwardMethod extends HttpServlet {
17 @Override
18 protected void doPost(HttpServletRequest req, HttpServletResponse resp)
19 throws ServletException, IOException {
20 doGet(req, resp);
21 }
22 @Override
23 protected void doGet(HttpServletRequest request, HttpServletResponse response)
24 throws ServletException, IOException {
25 request.getRequestDispatcher("/test.html").forward(request, response);
26 }
27 }
运行结果是这个样子的:
时间： 2024-12-23 22:06:51