遇到的问题是: 前台利用Ajax, get方式向后台发送中文数据出现乱码.
解决办法是前台两次编码, 后台一次解码即可.
前台jsp文件
1 var text = "张三"; 3 var username = encodeURI(encodeURI(text));
后台servlet代码
1 String username =URLDecoder.decode("对应字段","utf-8");
简单登录校验案例.
案例说明:为验证Ajax请求后端控制台中文乱码问题是否解决.
简单登录界面, 用户输入用户名登录. 若用户名未输入用户名则提示"用户名不能为空";若用户名输入为"张三"则提示用户名已被占用.其它均无提示.
前台页面index.jsp
1 <%-- 2 Created by IntelliJ IDEA. 3 User: hejjon 4 Date: 2019/6/3 5 Time: 10:19 6 To change this template use File | Settings | File Templates. 7 --%> 8 <%@ page contentType="text/html;charset=UTF-8" language="java" %> 9 <% 10 String path = request.getContextPath(); 11 String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() 12 + path + "/"; 13 %> 14 <html> 15 <head> 16 <base href="<%=basePath%>"> 17 <title>用户登录界面</title> 18 <script type="text/javascript"> 19 var xhr; 20 function change() { 21 22 var val = document.getElementById("uname").value; 23 var uname = encodeURI(encodeURI(val)); 24 25 if (uname === "") { 26 document.getElementById("namespan").innerHTML = "用户名不能为空"; 27 } else { 28 // 创建xhr对象 29 xhr = new XMLHttpRequest(); 30 // 与服务器建立连接 31 xhr.open("get", "servlet/login?uname=" + uname, true); 32 // 执行回调函数 33 xhr.onreadystatechange = process; 34 // 发送数据 35 xhr.send(null); 36 } 37 38 } 39 40 function process() { 41 if (xhr.readyState == 4 && xhr.status == 200) { 42 // 接收后台响应 43 var text = xhr.responseText; 44 document.getElementById("namespan").innerHTML = text; 45 } 46 } 47 </script> 48 </head> 49 <body> 50 <p> 51 用户: <input type="text" name="uname" id="uname" onblur="change()"/><span id="namespan"></span> 52 </p> 53 <p> 54 密码: <input type="password" name="pwd" id="pwd"/> 55 </p> 56 </body> 57 </html>
后台LoginServlet.java
1 import javax.servlet.ServletException; 2 import javax.servlet.annotation.WebServlet; 3 import javax.servlet.http.HttpServlet; 4 import javax.servlet.http.HttpServletRequest; 5 import javax.servlet.http.HttpServletResponse; 6 import java.io.IOException; 7 import java.io.PrintWriter; 8 import java.net.URLDecoder; 9 10 11 @WebServlet("/servlet/login") 12 public class LoginServlet extends HttpServlet { 13 @Override 14 protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { 15 // 设置后台响应文本格式 16 resp.setContentType("text/html;charset=utf-8"); 17 // 接收前台请求 18 String uname = URLDecoder.decode(req.getParameter("uname")); 19 20 // System.out.println(uname); 21 22 PrintWriter out = resp.getWriter(); 23 if ("张三".equals(uname)) { 24 out.print("用户名已被占用"); 25 } else { 26 out.print("用户名可用"); 27 } 28 } 29 } 30