3.实现重定向(状态码:302)=《路径/ /》
1.重定向的定义: 一个web资源收到客户端的请求后，他会通知客户端去访问另一个web资源，这个过程就叫做重定向。 2.常见场景: 用户登入 void sendRedirect(String var1) throws IOException;
package com.Jsxs.Servlet; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; public class RedirectServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.sendRedirect("/Servelete03_war/demo2"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
向映射demo2进行跳转的操作
基本原理的操作:
resp.setHeader("Location","/Servelete03_war/demo2"); resp.setStatus(HttpServletResponse.SC_FOUND); 302 代替上面的操作: resp.sendRedirect("/Servelete03_war/demo2");
4.读取前端信息
请你说说重定向和转发的区别: (1).相同点: 页面都会跳转 (2).不同点: 请求转发的时候: url不会改变 重定向的时候，url会改变
在jsp文件中，输入汉字的时候el表达式，需要加上: <%@page contentType="text/html; charset=UTF-8" %> 为了防止产生乱码的现象。
转发:
Java
package com.Jsxs.Servlet; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; public class Demo5 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("UTF-8"); resp.setContentType("text/html"); resp.getWriter().println("哈哈哈，我是demo5页面"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
JSP
<html> <body> <h2>Hello World!</h2> <%@page contentType="text/html; charset=UTF-8" %> <form action="${pageContext.request.contextPath}/demo5" method="get"> 用户名: <input type="text" name="username" placeholder="请输入您的用户名"> 密码: <input type="password" name="password" placeholder="请输入您的密码"> <input type="submit"> </form> </body> </html>
利用了表单转发
重定向: • 1
package com.Jsxs.Servlet; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; public class Demo5 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setCharacterEncoding("UTF-8"); resp.setContentType("text/html"); String username = req.getParameter("username"); String password = req.getParameter("password"); System.out.println(username+" "+password); resp.sendRedirect("/Servelete03_war/succes.jsp"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
<html> <body> <h2>Hello World!</h2> <%@page contentType="text/html; charset=UTF-8" %> <form action="${pageContext.request.contextPath}/demo5" method="get"> 用户名: <input type="text" name="username" placeholder="请输入您的用户名"> 密码: <input type="password" name="password" placeholder="请输入您的密码"> <input type="submit"> </form> </body> </html>
(十一)、HttpServletRequest（获取客户端信息）
HttpServletRequest代表客户端的请求，用户通过http协议访问服务器，Http请求 中的所有信息会被封装到HttpServletRequest,通过这个HttpServletRequest的方法 获得客户端的所有信息。
35.获取前端 传递的参数
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1>登入</h1> <div> <form action="${pageContext.request.contextPath}/demo1" method="post"> 用户名: <input type="text" name="username" placeholder="请输入您的账号"> <br/> 密码: <input type="password" name="password" placeholder="请输入您的密码"> <br/> 爱好: <input type="checkbox" name="s" value="girl"> 女孩 <input type="checkbox" name="s" value="sing"> 唱歌 <input type="checkbox" name="s" value="song"> 跳舞 <input type="checkbox" name="s" value="playGrame"> 打牌 <input type="submit"> <br/> </form> </div> </body> </html>
succes.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> </head> <body> <h1>欢迎来到吉士先生的世界?</h1> </body> </html>
java
package com.Jsxs.Servlet; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.Arrays; public class Demo1 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 响应编码 resp.setCharacterEncoding("utf-8"); // 请求编码 req.setCharacterEncoding("utf-8"); String username = req.getParameter("username"); String password = req.getParameter("password"); // 获取多个 String[] s = req.getParameterValues("s"); System.out.println("====================================="); System.out.println(password); System.out.println(username); System.out.println(Arrays.toString(s)); System.out.println("====================================="); resp.sendRedirect("/Servelete04_war/succes.jsp"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doGet(req, resp); } }
