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转发和重定向又是什么“垃圾”——教你再分类 - 泰斗贤若如

 4 years ago
source link: https://www.cnblogs.com/zyx110/p/11229865.html
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转发和重定向详解

转发与重定向的区别

         前言：之前写了几篇JSP的博客，现在又回过头来看Servlet，温故而知新，再回顾回顾，总会有收获的。以前学习Servlet感觉内容很多，现在看的时候，其实也没多少东西，只需知道Servlet的生命周期，Servlet的实现方式，ServletContext作用域，接收和响应，转发和重定向，我觉得差不多够用了。当然，要是细究的话也不止这些，我针对的是新手。

转发与重定向简介

转发和重定向都是实现页面跳转，也就是说，当我们访问一个Servlet 的时候，Servlet帮我们跳转到另一个界面。

转发与重定向的区别

实现转发调用的是HttpServletRequest对象中的方法

实现重定向调用的是HttpServletResponse对象中的方法

转发时浏览器中的url地址不会发生改变

重定向时浏览器中的url地址会发生改变

转发时浏览器只请求一次服务器

重定向时浏览器请求两次服务器

转发能使用request带数据到跳转的页面

重定向能使用ServletContext带数据到跳转的页面

代码演示转发和重定向

package servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/login")
public class ServletDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取表单提交过来的数据
//getParameter()方法可以获取请求的参数信息
String name = req.getParameter("name");
String password = req.getParameter("password");
//打印获取到的参数信息
System.out.println("name:"+name);
System.out.println("password:"+password);
//如果name=admin,password=123,则跳转到succee.jsp,否则跳转到fail.jsp
if("admin".equals(name)&&"123".equals(password)){
//通过转发实现跳转
req.getRequestDispatcher("/success.jsp").forward(req,resp);
}else {
//通过重定向实现跳转
resp.sendRedirect("/fail.jsp");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}

　　

1640688-20190723093229844-1978895768.png
1640688-20190723093238418-1483978900.png
1640688-20190723093247838-458448488.png
1640688-20190723093259200-502253343.png

1640688-20190723093308449-629206060.png

JSP代码

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录</title>
</head>
<body>
<form action="/login">
<table align="center">
<tr>
<td>账号:</td>
<td><input type="text" name="name"></td>
</tr>
<tr>
<td>密码:</td>
<td><input type="text" name="password"></td>
</tr>
<tr>
<td><input type="submit" value="登录"></td>
<td><input type="reset" value="重置"></td>
</tr>
</table>
</form>
</body>
</html>

转发和重定向如何带数据到某个页面

 

1640688-20190723093547247-6435955.png
package servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/login")
public class ServletDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//通过转发带数据
req.setAttribute("name","张三");
req.getRequestDispatcher("/send.jsp").forward(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}

send.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>转发和重定向传代数据练习</title>
</head>
<body>
<%
//1、接收转发传代的数据
String name =  (String) request.getAttribute("name");
out.println("转发传代的数据："+name);
%>
</body>
</html>

 

1640688-20190723093615665-1013598821.png
package servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/login")
public class ServletDemo extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//通过重定向带数据
ServletContext servletContext = this.getServletContext();
servletContext.setAttribute("name","王二麻子");
resp.sendRedirect("/send2.jsp");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}

send2.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>转发和重定向传代数据练习</title>
</head>
<body>
<%
//1、接收重定向传代的数据
String name1 = (String)application.getAttribute("name");
out.println("重定向传代的数据："+name1);
%>
</body>
</html>

 

1640688-20190723093642845-1482927093.png

 

1640688-20190723093651701-231982013.png

 

1640688-20190723093701076-1453614699.png

 

1640688-20190723093709060-651541422.png

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<form action="CountServlet" method="post">
<h3>加法计算器</h3>
加数1：<input type="number" name="one">
加数2：<input type="number" name="two">
<input type="submit" value="计算">
</form>
</body>
</html>

count.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
计算结果：<%=request.getAttribute("count")%>
<!--计算结果：<%=application.getAttribute("count")%>-->
</body>
</html>

Servlet

package servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/CountServlet")
public class CountServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String one=request.getParameter("one");
int o=Integer.parseInt(one);//强制转换，将String类型的数据转换成int类型
String two=request.getParameter("two");
int t=Integer.parseInt(two);//强制转换，将String类型的数据转换成int类型
System.out.println(one+"   "+two);
int c=o+t;
String co=String.valueOf(c);//将int类型的数据转换成String类型
//转发，可以携带数据
request.setAttribute("count",co);
request.getRequestDispatcher("count.jsp").forward(request,response);
//用于存放数据
//        ServletContext s=this.getServletContext();
//        s.setAttribute("count",co);
//重定向只能依靠ServletContext获取数据
//  response.sendRedirect("count.jsp");
System.out.println(co);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}

Servlet分享到此结束，想了解更多的朋友可以看之前总结过的博客《Servlet》,和《JSP》 ,更多精彩等你来学习。

*****************************************************************************************************

我的博客园地址：https://www.cnblogs.com/zyx110/

  本文已独家授权给脚本之家(jb51net)公众号独家发布

posted @ 2019-07-23 09:42  泰斗贤若如  阅读(1149)  评论(13)  编辑  收藏

#1楼

2019-07-23 10:21

Advance_Man

#2楼

[楼主] 2019-07-23 10:22

泰斗贤若如

#3楼

2019-07-23 11:06

一個未来

#5楼

[楼主] 2019-07-23 12:21

泰斗贤若如

#6楼

2019-07-24 07:51

又见秋枫

#7楼

[楼主] 2019-07-24 08:16

泰斗贤若如

#8楼

[楼主] 2019-07-24 08:18

泰斗贤若如

#9楼

2019-07-24 08:47

hsm_computer

#10楼

[楼主] 2019-07-24 08:50

泰斗贤若如

#11楼

2019-07-24 09:04

宋者为王

#12楼

[楼主] 2019-07-24 09:06

泰斗贤若如

#13楼

2020-09-24 17:10

flyfishing_1991


report

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