1、添加JSON数据转换驱动

 1、pom文件添加JSON依赖
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
      <version>2.9.0</version>
    </dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
      <version>2.9.0</version>
    </dependency>
2、全局配置文件添加驱动，使得可以调用JSON数据转化的类
<mvc:annotation-driven/>(http://www.springframework.org/schema/mvc)

2、Cotroller类和响应的HTML

@Controller
class A{
    //返回字符串
    @ReuqestMapping("/uri")
    @ResponseBody//设置为响应体
    public String test01(){
        return "String";
    }  
    //返回对象
    @ReuqestMapping("/uri")
    @ResponseBody//设置为响应体
    public Student test01(Student stu){
        return stu;
    } 
    //List
    @ReuqestMapping("/uri")
    @ResponseBody//设置为响应体
    public List<Student> test01(List<Student> stus){
        return stus;
    }  
}

3、示例

@Controller
public class TestClass {
    @RequestMapping(value = "/some.do",method = RequestMethod.POST)
    @ResponseBody
    public Student test01(Student student){
        return student;
    }
    @RequestMapping(value = "/string.do",method = RequestMethod.POST,produces="application/json;charset=UTF-8")//设置返回内容为String，编码格式
    @ResponseBody
    public String test03(){
        return "student";
    }
    @RequestMapping(value = "/other.do",method = RequestMethod.POST)
    @ResponseBody
    public List<Student> test02(){
        List<Student> students = new ArrayList<>();
        students.add(new Student(34,"name1"));
        students.add(new Student(234,"name2"));
        return students;
    }
}

<meta charset="UTF-8">
    <script type="text/javascript" src="js/jquery-3.4.1.js"></script>
    <script type="text/javascript">
        $(function () {
            $("#a").click(function () {
                $.ajax({
                    url:"some.do",
                    data:{
                        name:"历史", age:23,
                    },
                    type:"post",
                    dataType:"json",
                    success: function (rep) {
                        alert(rep.name+"\t"+rep.age)
                    }
                })
            })
            $("#b").click(function () {
                $.ajax({
                    url:"string.do",
                    type:"post",
                    success: function (rep) {
                        alert(rep)
                    }
                })
            })
            $("#c").click(function () {
                $.ajax({
                    url:"other.do",
                    type:"post",
                    dataType:"json",
                    success: function (rep) {
                       $.each(rep,function (i,res) {
                            alert(res.name+"\t"+res.age)
                       })
                    }
                })
            })
        })
    </script>
    <button id="a">点击1</button>
    <button id="b">点击2</button>
    <button id="c">点击3</button>