jsp中 RequestDispatcher接口的两种跳转:forward()和include()
发布于 2015-05-19 05:55:04 | 262 次阅读 | 评论: 0 | 来源: 网友投递
JSP JAVA公司的WEB开发编程语言
JSP全名为Java Server Pages - java服务器页面是由Sun Microsystems公司倡导、许多公司参与一起建立的一种动态网页技术标准。JSP技术有点类似ASP技术，它是在传统的网页HTML（标准通用标记语言的子集）文件(*.htm,*.html)中插入Java程序段(Scriptlet)和JSP标记(tag)，从而形成JSP文件，后缀名为(*.jsp)。
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
package com.gys;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(
name="demo",
urlPatterns={"/include"}
)
public class IncludeMethod extends HttpServlet{
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out=response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" <h1>第一个servlet</h1>");
RequestDispatcher dispatcher=request.getRequestDispatcher("/includeSecond");
dispatcher.include(request, response);
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
IncludeMethod2.java
package com.gys;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(
name="include2",
urlPatterns={"/includeSecond"}
)
public class IncludeMethod2 extends HttpServlet{
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out=response.getWriter();
out.println("这是第二个servlet(被包涵在第一个servlet里面)");
}
}
测试结果:
二.forward()
forwardMethod.java代码
package com.gys2;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(
name="forwardMethod",
urlPatterns={"/test"}
)
public class forwardMethod extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGet(req, resp);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.getRequestDispatcher("/test.html").forward(request, response);
}
}
运行结果是这个样子的:
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