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：