实现一个ajax请求的简单例子

效果：在前端页面的text框输入一个id，点击按钮，发送ajax请求到数据库查询对应用户数据返回，将用户信息显示在页面，实现局部刷新。

不说废话直接来！

1.前端的jsp页面 （代码的注释写的非常详细了，直接看代码就行了，我就不再解释了）

<%@ page contentType="text/html;charset=UTF-8" language="java" %>


    
    

    
    





获取
名字：
年龄

2.controller的代码

    // 访问jsp页面
    @RequestMapping("/testAjax")
    public String testAjax(){
        return "TestAjax";
    }

    // jsp页面的请求url
    @RequestMapping("/getUser")
    @ResponseBody
    public String getUser(String id) throws InterruptedException {
        User user = userService.get(id);
        User user1 = new User();
        String s = JSON.toJSONString(user1);  // 就算数据库查不到也不会返回Null
        if(user!=null){
            s = JSON.toJSONString(user);
        }
        // Thread.sleep(5000);    // 测试异步就放开它
        return s;
    }

这里 getUser 方法里面用到了阿里的 fastjson 的json解析工具（用来对象转json字符串的），放个maven依赖

    com.alibaba
    fastjson
    1.2.47

3.UserService

package com.liqiye.springbootdemo.service;

import com.liqiye.springbootdemo.entity.User;
import com.liqiye.springbootdemo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

/**
 * @author liqiye
 * @description
 * @date 2019/4/6
 */
@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public User get(String id){
        return userMapper.get(id);
    }

}

4.UserMapper

package com.liqiye.springbootdemo.mapper;

import com.liqiye.springbootdemo.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

// @Mapper
public interface UserMapper {

    @Select("select * from user where id = #{id}")
    User get(@Param("id")String id);

}

5.User

package com.liqiye.springbootdemo.entity;

import com.liqiye.springbootdemo.utils.SetName;

/**
 * @author liqiye
 * @description
 * @date 2019/4/6
 */
public class User {

    public Integer id;
    @SetName(value = "张三")
    public String name;
    public Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public User() {
    }

    public User(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

6.数据库

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;

INSERT INTO `user` VALUES ('1', '张三', '23');
INSERT INTO `user` VALUES ('2', '李四', '24');
INSERT INTO `user` VALUES ('3', '王五', '25');

7.测试：成功！