json转换学习

文章部分代码实体类可以忽略。

原文：https://www.cnblogs.com/free-dom/p/5801866.html

代码如下：

package covert;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

/**
 * 
 * @author jack 陈
 *
 */
public class Student {

    private String name;
    private String address;
    private String age;

    public String getName() {
        return name;
    }

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

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getAge() {
        return age;
    }

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

    public Student(String name, String address, String age) {
        super();
        this.name = name;
        this.address = address;
        this.age = age;
    }

    public Student() {
        super();
       
    }

    @Override
    public String toString() {
        return "Student [name=" + name + ", address=" + address + ", age=" + age + ", getName()="
                + getName() + ", getAddress()=" + getAddress() + ", getAge()=" + getAge()
                + ", getClass()=" + getClass() + ", hashCode()=" + hashCode() + ", toString()="
                + super.toString() + "]";
    }

---

    /**
     * 
     * json转化，数组，对象
     */
    public static void convertjson() {

        Student s = new Student();
        s.setAddress("北京东城区");
        s.setAge("56");
        s.setName("刘德华");

        // 对象
        JSONObject jsonObject = JSONObject.fromObject(s);
        // 数组
        JSONArray jsonArray = JSONArray.fromObject(s);

        // 转化
        String js1 = jsonObject.toString();
        String js2 = jsonArray.toString();

        // 打印
        System.out.println(js1);
        System.out.println(js2);

    }

---

    //json 转 字符串
    public static void jsontostring() {
        // 定义两种不同格式的字符串
        String objectStr = "{\"name\":\"JSON\",\"age\":\"24\",\"address\":\"北京市西城区\"}";
        String arrayStr = "[{\"name\":\"JSON\",\"age\":\"24\",\"address\":\"北京市西城区\"}]";

        // 1、使用JSONObject
        JSONObject object = JSONObject.fromObject(objectStr);
        Student stu = (Student) JSONObject.toBean(object, Student.class);

        // 2、使用JSONArray
        JSONArray jsonArray = JSONArray.fromObject(arrayStr);
        // 获得jsonArray的第一个元素
        Object o = jsonArray.get(0);
        JSONObject jsonObject2 = JSONObject.fromObject(o);
        Student stu2 = (Student) JSONObject.toBean(jsonObject2, Student.class);
        System.out.println("stu:" + stu);
        System.out.println("stu2:" + stu2);

    }

---

    // list转json（注意：list只能转json数组）
    public static void listtojson() {
        Student stu = new Student();
        stu.setName("JSON");
        stu.setAge("23");
        stu.setAddress("北京市海淀区");
        List<Student> list = new ArrayList<Student>();
        list.add(stu);

        // 转化
        //JSONObject listobjest = JSONObject.fromObject(list);
        JSONArray listarray = JSONArray.fromObject(list);
        
        //打印
        //System.out.println(listobjest.toString());
        System.out.println(listarray.toString());
    }

---

    // json转list
    public static void jsontolist() {
        
        String arrayStr="[{\"name\":\"JSON\",\"age\":\"24\",\"address\":\"北京市西城区\"}]";
        //转化为list
        List<Student> list2= JSONArray.toList(JSONArray.fromObject(arrayStr), Student.class);
        for (Student stu : list2) {
            System.out.println(stu);
        }
        //转化为数组
        
        Student[] array = (Student[]) JSONArray.toArray(JSONArray.fromObject(arrayStr), Student.class);
        for (Student stu2 : array) {
           System.out.println(stu2);
        }
        
    }

---

    //map转json
    public static void mapToJSON(){
        Student stu=new Student();
        stu.setName("JSON");
        stu.setAge("23");
        stu.setAddress("中国上海");
        Map<String,Student> map=new HashMap<String,Student>();
        map.put("first", stu);
        
        //1、JSONObject
        JSONObject mapObject=JSONObject.fromObject(map);
        System.out.println("mapObject"+mapObject.toString());
        
        //2、JSONArray
        JSONArray mapArray=JSONArray.fromObject(map);
        System.out.println("mapArray:"+mapArray.toString());
    }

---

    //json转map
    public static void jsonToMap(){
        String strObject="{\"first\":{\"address\":\"中国上海\",\"age\":\"23\",\"name\":\"JSON\"}}";
        
        //JSONObject
        JSONObject jsonObject=JSONObject.fromObject(strObject);
        Map map=new HashMap();
        map.put("first", Student.class);

        //使用了toBean方法，需要三个参数 
        MyBean my=(MyBean)JSONObject.toBean(jsonObject, MyBean.class, map);
        System.out.println(my.getFirst());
        
    }

---

    
    public static void main(String[] args) {
        //convertjson();
        System.out.println("===================");
        //jsontostring();
        System.out.println("===================");
        //listtojson();
        System.out.println("===================");
        //jsontolist();
        System.out.println("===================");
        mapToJSON();
        System.out.println("===================");
        jsonToMap();
    }
    
    
}

MyBean类：

package covert;
/**
 * 
 * @author 
 *
 */
public class MyBean {

    private Student first;

    public Student getFirst() {
        return first;
    }

    public void setFirst(Student first) {
        this.first = first;
    }
    
}

显示结果：