Servlet跳转

最新推荐文章于 2020-09-24 01:45:20 发布

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#jave #servlet #javeweb #javeEE

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本文详细介绍了在Servlet中实现服务器内跳转与重定向的方法。通过示例代码展示了如何使用forward标签实现服务器内跳转，并保持请求参数的有效性；同时对比了使用sendRedirect方法进行重定向的特点。

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在Servlet内实现跳转

常见的Servlet内跳转有两种：
（1）重定向：对应JSP内置对象中的sendRedirect
respose.sendRedirect(“URL地址”);
（2）服务器内跳转：对应JSP中的forward标签
ServletContext application = this.getServletContext();
ServletContext application = this.getServletContext();
RequestDispatcher rd = application.getRequestDispatcher(“URL地址”);
rd.forward(request, response);

编写跳转Servlet

创建一个名为JumpServlet的Servlet
代码如下：

package cn.lystery.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class JumpServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        String user = "Lystery";//模拟用户
        req.setAttribute("user", user);
        ServletContext application = this.getServletContext();
        RequestDispatcher rd = application.getRequestDispatcher("/index.jsp");
        rd.forward(req, resp);
    }

}

配置Servlet

配置代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
                    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <servlet>
        <servlet-name>JumpServlet</servlet-name>
        <servlet-class>cn.lystery.servlet.JumpServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>JumpServlet</servlet-name>
        <url-pattern>/JumpServlet</url-pattern>
    </servlet-mapping>

</web-app>

编写index.jsp界面

index.jsp页面存在于WebContent目录下
这里写图片描述
编写index.jsp界面

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>欢迎界面</title>
</head>
<body>
欢迎<br>
<%=request.getAttribute("user") %>
</body>
</html>

部署并测试JumpServlet

在地址栏输入http://localhost:8080/MyServlet/JumpServlet
这里写图片描述
发现已经跳转到index.jsp界面，显示出对应内容

使用重定向进行跳转

对JumpServlet进行如下更改

package cn.lystery.servlet;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class JumpServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        String user = "Lystery";//模拟用户
        req.setAttribute("user", user);
        resp.sendRedirect("index.jsp");
    }

}