3个不同jar包的JSONObject的区别

• com.alibaba.fastjson.JSONObject
• net.sf.json.JSONObject
• org.json.JSONObject

java对象和json数据之间的转换方式一般有两种，一种是引用第三方的jar包，如Gson（谷歌）、Fastjson（阿里）、Jackson等，这种方式优点是语法精练，可以实现一句话转化，但缺点是会引入庞大的第三方库。
第二种是直接使用Java自带的org.json解析，但这个库功能比较基础，解析会写很多重复的代码。

　　

一 、com.alibaba.fastjson.JSONObject的使用

1 POM.xml

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.51</version>
</dependency>

　　

2 Json字符串与Map、List、object之间的相互转换

  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import com.alibaba.fastjson.JSON;
  import com.alibaba.fastjson.JSONArray;
  import com.alibaba.fastjson.JSONObject;
   
 public class TestFastJson {
  
      public static void main(String[] args){
          json2JsonObject();//将Json字符串转换为JSONObject对象
          json2JavaBean();//将Json字符串转换为JavaBean对象
          json2JsonArray();//将Json字符串转换为JSONArray对象
          json2JavaBeanList();//将Json字符串转换为JavaBean的集合
          javaBean2Json();//将JavaBean转换为Json格式的数据
          javaBean2JsonObject();//将JavaBean转换为JSONObject对象
          json2ListInMap();//从Json字符串的Map中获取List对象
          list2JsonInMap();//将含list的Map对象转换为Json字符串
          stringToMap();//json字符串转map
          mapToString();//map转json字符串
          mapToJsonObject();//map转json对象
          testList2String()；//list转json字符串
      }
      
      private static void json2JsonObject() {
          String s = "{"name":"peter"}";
          JSONObject object = JSON.parseObject(s);
          System.out.println(object.get("name"));
      }
     
     private static void json2JavaBean() {
         String s = "{"id":"17051801","name":"lucy"}";
         User user = JSON.parseObject(s, User.class);
         System.out.println(user.getId());
         System.out.println(user.getName());
     }
     
     private static void json2JsonArray() {
         String s = "[{"id":"17051801","name":"lucy"},{"id":"17051802","name":"peter"}]";
         JSONArray array = JSON.parseArray(s);
         for (int i = 0; i < array.size(); i++) {
             //JSONArray中的数据转换为String类型需要在外边加"";不然会报出类型强转异常！
             String str = array.get(i)+"";
             JSONObject object = JSON.parseObject(str);
             System.out.println(object.get("name"));
         }
     }
     
     private static void json2JavaBeanList() {
         String s = "[{"id":"17051801","name":"lucy"},{"id":"17051802","name":"peter"}]";
         List<User> list = JSON.parseArray(s, User.class);
         for (User user : list) {
             System.out.println(user.getName());
         }
     }
     
      private static void javaBean2Json() {
         User user = new User("17051801", "lucy");
         String string = JSON.toJSONString(user);
         System.out.println(string);
     }
     
     private static void javaBean2JsonObject() {
         User user = new User("17051801", "lucy");
         JSONObject json = (JSONObject) JSON.toJSON(user);
         System.out.println(json.get("id"));
     }
     
     private static void json2ListInMap() {
         String s = "{json:[{id:"17051801","name":"lucy"},{id:"17051802","name":"peter"},"
                 + "{id:"17051803","name":"tom"},{id:"17051804","name":"lily"}]}";
         //将Json字符串转换为JSONObject对象,并取出list对象的值
         JSONObject object = JSON.parseObject(s);
         Object objArray = object.get("json");
         String str = objArray+"";
         //方式1:转换成JSONArray对象形式
         JSONArray array = JSON.parseArray(str);
         for (int i = 0; i < array.size(); i++) {
             JSONObject obj = JSON.parseObject(array.get(i)+"");
             System.out.println(obj.get("name"));
         }
         //方式2:转换成List<JavaBean>形式
         List<User> list = JSON.parseArray(str, User.class);
         for (User user : list) {
             System.out.println(user.getName());
         }
     }
     
     private static void list2JsonInMap() {
         //方式1:构建一个带有list的JavaBean对象
         School school = new School();
         school.setId("1");
         school.setName("schoolA");
         
         User user1 = new User();
         user1.setId("17051801");
         user1.setName("lucy");
         User user2 = new User();
         user2.setId("17051802");
         user2.setName("peter");
         
         school.getStudents().add(user1);
         school.getStudents().add(user2);
         //将JavaBean对象转换成Json字符串
         String string1 = JSON.toJSONString(school);
         System.out.println(string1);
         
         //方式2:构建一个带有list的Map对象
         Map<String, Object> map1 = new HashMap<String,Object>();
         map1.put("id", "17051801");
         map1.put("name", "lucy");
         
         Map<String, Object> map2 = new HashMap<String,Object>();
         map2.put("id", "17051802");
         map2.put("name", "peter");
         
         List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
         list.add(map1);
         list.add(map2);
         
         Map<String, Object> map = new HashMap<String,Object>();
         map.put("id", "1");
         map.put("name", "schoolA");
         map.put("students", list);
         //将map对象转换成Json字符串
         String string2 = JSON.toJSONString(map);
         System.out.println(string2);
     }
 
      private static void stringToMap(){
          String str = "{"age":"24","name":"cool_summer_moon"}";
          JSONObject  jsonObject = JSONObject.parseObject(str);
          //json对象转Map
          Map<String,Object> map = (Map<String,Object>)jsonObject;
          System.out.println("map对象是：" + map);
          Object object = map.get("age");
          System.out.println("age的值是"+object);
     }
     
     private static void mapToString(){
         Map<String,Object> map = new HashMap<>();
         map.put("age", 24);
         map.put("name", "cool_summer_moon");
         String jsonString = JSON.toJSONString(map);
         System.out.println("json字符串是："+jsonString);
     }
 
     private static void mapToJsonObject(){
        Map<String,Object> map = new HashMap<>();
        map.put("age", 24);
        map.put("name", "cool_summer_moon");
        JSONObject json = new JSONObject(map);
        System.out.println("Json对象是：" + json);
 
     }
 
     /** 
     * 测试包装类型的List转换为json字符串 
     */   
    public static void testList2String() {  
        List<Long> longs = new ArrayList<Long>();  
        longs.add(1L);  
        longs.add(2L);  
        longs.add(3L);  
        String actual = JSON.toJSONString(longs);  
        Assert.assertEquals("[1,2,3]", actual);  
    }
 
}

二 、org.json.JSONObject的使用

1.引入org.json依赖

		<dependency>
			<groupId>org.json</groupId>
			<artifactId>json</artifactId>
			<version>20160810</version>
		</dependency>

　　

3.JSONObject转javaBean

    public static void main(String[] args) {
        String str="{"student":[{"name":"leilei","age":23},{"name":"leilei02","age":23}]}";
        Student stu = null;
        List<Student> list = null;
        try {
            ObjectMapper objectMapper=new ObjectMapper();
            StudentList studentList=objectMapper.readValue(str, StudentList.class);
            list=studentList.getStudent();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        for(Student s:list){
            System.out.println(s.getName());
        }
    }

　　ObjectMapper objectMapper=new ObjectMapper();
　　out = objectMapper.readValue(org.json.JSONObject.valueToString(arg0), OutputObject.class);

三 net.sf.json.JSONObject的使用

1 引入maven依赖

最后一行需要保留，有两个jdk版本的实现：json-lib-2.1-jdk13.jar和json-lib-2.1-jdk15.jar

　　　　　<dependency>
            <groupId>net.sf.json-lib</groupId>
            <artifactId>json-lib</artifactId>
            <version>2.4</version>
            <classifier>jdk15</classifier>
        </dependency>

　　

使用范例

package json;

import net.sf.json.JSON;
import net.sf.json.JSONObject;
import net.sf.json.xml.XMLSerializer;

public class JSONObject_1_3 {
public static void javaToJSON() {
System.out.println("java代码封装为json字符串");
JSONObject jsonObj = new JSONObject();
jsonObj.put("username", "张三");
jsonObj.put("password", "123456");
System.out.println("java--->json 
" + jsonObj.toString());
}

public static void jsonToJAVA() {
System.out.println("json字符串转java代码");
String jsonStr = "{"password":"123456","username":"张三"}";
JSONObject jsonObj = JSONObject.fromString(jsonStr);
String username = jsonObj.getString("username");
String password = jsonObj.optString("password");
System.out.println("json--->java
 username=" + username
+ "	 password=" + password);
}

public static void jsonToXML() {
System.out.println("json字符串转xml字符串");
String jsonStr = "{"password":"123456","username":"张三"}";
JSONObject json = JSONObject.fromString(jsonStr);
XMLSerializer xmlSerializer = new XMLSerializer();
xmlSerializer.setRootName("user_info");
xmlSerializer.setTypeHintsEnabled(false);
String xml = xmlSerializer.write(json);
System.out.println("json--->xml 
" + xml);
}

public static void javaBeanToJSON() {
System.out.println("javabean转json字符串");
UserInfo userInfo = new UserInfo();
userInfo.setUsername("张三");
userInfo.setPassword("123456");
JSONObject json = JSONObject.fromBean(userInfo);
System.out.println("javabean--->json 
" + json.toString());
}

public static void javaBeanToXML() {
System.out.println("javabean转xml字符串");
UserInfo userInfo = new UserInfo();
userInfo.setUsername("张三");
userInfo.setPassword("123456");
JSONObject json = JSONObject.fromBean(userInfo);
XMLSerializer xmlSerializer = new XMLSerializer();
String xml = xmlSerializer.write(json, "UTF-8");
System.out.println("javabean--->xml 
" + xml);
}

public static void xmlToJSON(){
System.out.println("xml字符串转json字符串");
String xml = "<?xml version="1.0" encoding="UTF-8"?><user_info><password>123456</password><username>张三</username></user_info>";
JSON json=XMLSerializer.read(xml);
System.out.println("xml--->json 
"+json.toString());
}

public static void main(String args[]) {
　　javaToJSON();
　　jsonToJAVA();
　　jsonToXML();
　　javaBeanToJSON();
　　javaBeanToXML();
　　xmlToJSON();
}
}

转自：https://blog.csdn.net/zhengTornado/article/details/102832587