json转对象，对象转json以及list转json

        
        
            com.alibaba
            fastjson
            1.2.76
        

@Data
public class Student {
    private String username;
    private String sex;
    private Integer age;
    private String addres;

    public Student() {
    }
    public Student(String username, String sex, Integer age, String addres) {
        this.username = username;
        this.sex = sex;
        this.age = age;
        this.addres = addres;
    }
}

1. JSONObject和JSonArray 都继承JSON
2. java实体类对应JSonObject ， list对象对应JSONArray

String jsonStr = JSONObject.toJSonString(实体类);

String jsonArrayStr = JSONArray.toJSonString(list对象);

String jsonStr= JSONObject.toJSonString(实体类);
JSonObject jsonObject=JSONObject.parseObject(jsonStr);

String jsonString = JSONArray.toJSonString(list对象);
JSonArray jsonArrayobjects =JSONArray.parseArray(jsonString);

步骤 json字符串先转成json对象，然后json对象在转成实体对象
示例：

    //对象转json字符串
    Student student=new Student("张三","男",25,"北京市海淀区");
    String jsonStr = JSONObject.toJSonString(student);
    
    //json字符串转对象
    JSonObject jsonObject = JSONObject.parseObject(jsonStr);
    Student studentNew = jsonObject.toJavaObject(Student.class);

转成list对象示例：

    //list对象转json字符串
    List list=new ArrayList<>();
    Student studenOne=new Student("李四","男",22,"山西省太原市");
    Student studenTwo=new Student("小红","女",20,"江西省九江市");
    list.add(studenOne);list.add(studenTwo);
    
    //list先转换成json字符串，json字符串在转成jsonarray对象，然后再转成java list对象
    String jsonArrayStr = JSONArray.toJSonString(list);
    JSonArray jsonArray = JSONObject.parseArray(jsonArrayStr);
    List listNew = jsonArray.toJavaList(Student.class);