实现一个ajax请求的简单例子

╰半夏微凉° 2024-02-19 19:50 44阅读 0赞

**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" %>
    <html>
    <head>
        <meta http-equiv="content-type" content="text/html;charset=utf-8"/>
        <title>测试ajax</title>
    
        <script src="http://code.jquery.com/jquery-latest.js"></script>
        <script type="text/javascript">
            $(document).ready(function () {
    
            });
            function method() {
                var val = $("#userId").val();
                $.ajax({
                    type:"GET",
                    url:"getUser",
                    // data:{"id":val},     // data参数是可选的，有多种写法，也可以直接在url参数拼接参数上去，例如这样：url:"getUser?id="+val,
                    data:"id="+val,
                    async:true,   // 异步，默认开启，也就是$.ajax后面的代码是不是跟$.ajx里面的代码一起执行
                    cache:true,  // 表示浏览器是否缓存被请求页面,默认是 true
                    dataType:"json",   // 返回浏览器的数据类型，指定是json格式，前端这里才可以解析json数据
                    success:function(data){
                        $("#name").text(data.name);
                        $("#age").text(data.age);
                    },
                    error:function(){
                        console.log("发生错误")
                        alert("发生错误");
                    },
                    complete:function(){
                        console.log("ajax请求完事，最终操作在这里完成")
                    }
                });
                // alert("测试异步")
            }
        </script>
    
    </head>
    <body>
    
    <input type="text" id="userId"/>
    <button onclick="method();">获取</button>
    <div>名字：<span id="name"></span></div>
    <div>年龄<span id="age"></span></div>
    </body>
    </html>

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

<dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.47</version>
    </dependency>

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！

![20190410163122556.png][]

[20190410163122556.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/2c1a496829fa4b7886b05b44177b7a6a.png