使用ajax对用户注册时，用户名进行检验

package cn.hopetesting.com.servlet;

import com.fasterxml.jackson.databind.ObjectMapper;

import javax.print.attribute.standard.JobOriginatingUserName;
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;
import java.util.HashMap;
import java.util.Map;

/**
 * @author newcityman
 * @date 2019/9/18 - 21:49
 */
@WebServlet("/findUserServlet")
public class FindUserServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 response.setContentType("application/json;charset=utf-8");
// response.setContentType("text/html;charset=utf-8");
 //1、获取参数username
 String username = request.getParameter("username");
 //2、调用service层判断用户名是否存在
 //期望服务器响应回的数据格式：{
 //("userExist:true,"msg","此用户名太受欢迎，请更换一个")，
 // ("userExist:false,"msg","此用户名可用")}
 Map,Object> map = new HashMap,Object>();
 if("tom".equals(username)){
//存在
 map.put("userExist",true);
 map.put("msg","此用户名太受欢迎，请更换一个");
 }else{
//不存在
 map.put("userExist",false);
 map.put("msg","此用户名可用");
 }
//将map转换为json，并且传递给客户端
 //将map转为json
 ObjectMapper mapper = new ObjectMapper();
 //并且传递给客户端
 mapper.writeValue(response.getWriter(),map);

 }

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
 }
}

html>
lang="en">

 charset="UTF-8">
 
 
 


 type="text" id="username" name="username" placeholder="请输入用户名">
 id="s_username">

 type="password" id="password" name="passowrd" placeholder="请输入密码">

 type="submit" value="提交">

转载于:https://www.cnblogs.com/newcityboy/p/11546071.html