用JSONObject解析和处理json数据

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（一）jar包下载

所需jar包打包下载百度网盘地址：https://pan.baidu.com/s/1c27Uyre

（二）常见场景及处理方法

1、解析简单的json字符串：

1 // 简单的json测试字符串2 public static final String JSON_SIMPLE = "{'name':'tom','age':16}";34 JSONObject obj = JSONObject.fromObject(JSON_SIMPLE);5 System.out.println("name is : " + obj.get("name"));6 System.out.println("age is : " + obj.get("age"));

输出：

name is : tom
age is : 16

2、解析嵌套的json字符串：

1 // 嵌套的json字符串2 public static final String JSON_MULTI = "{'name':'tom','score':{'Math':98,'English':90}}";3 JSONObject obj = JSONObject.fromObject(JSON_MULTI);4 System.out.println("name is : " + obj.get("name"));5 System.out.println("score is : " + obj.get("score"));67 JSONObject scoreObj = (JSONObject) obj.get("score");8 System.out.println("Math score is : " + scoreObj.get("Math"));9 System.out.println("English score is : " + scoreObj.get("English"));

输出：

name is : tom
score is : {"English":90,"Math":98}
Math score is : 98
English score is : 90

3、把bean对象转化成JSONObject对象：

Person、Info、Score类分别如下：（注：要定义成独立的三个public类，不能定义成内部类或非public类，否则会转换异常）

1 public class Person { 2 private String name; 3 4 private Info info; 5 6 public String getName() { 7 return name; 8 } 910 public void setName(String name) {11 this.name = name;12 }1314 public Info getInfo() {15 return info;16 }1718 public void setInfo(Info info) {19 this.info = info;20 }2122 @Override23 public String toString() {24 return "Person [name=" + name + ", info=" + info + "]";25 }2627 }

1 public class Info { 2 private int age; 3 private Score score; 4 5 public int getAge() { 6 return age; 7 } 8 9 public void setAge(int age) {10 this.age = age;11 }1213 public Score getScore() {14 return score;15 }1617 public void setScore(Score score) {18 this.score = score;19 }2021 @Override22 public String toString() {23 return "Info [age=" + age + ", score=" + score + "]";24 }2526 }

1 public class Score { 2 private String math; 3 private String english; 4 5 public String getMath() { 6 return math; 7 } 8 9 public void setMath(String math) {10 this.math = math;11 }1213 public String getEnglish() {14 return english;15 }1617 public void setEnglish(String english) {18 this.english = english;19 }2021 @Override22 public String toString() {23 return "Score [math=" + math + ", english=" + english + "]";24 }2526 }

转换方法：

1 Score score = new Score(); 2 score.setEnglish("A"); 3 score.setMath("B"); 4 5 Info info = new Info(); 6 info.setAge(20); 7 info.setScore(score); 8 9 Person person = new Person();10 person.setInfo(info);11 person.setName("Tim");1213 JSONObject obj = JSONObject.fromObject(person);14 System.out.println(obj.toString());

输出：

{
    "name": "Tim",
    "info": {
        "score": {
            "english": "A",
            "math": "B"
        },
        "age": 20
    }
}

4、把json数组转换成JsonObject数组：

1 // 数组形式的json 2 public static final String JSON_ARRAY = "[{'name':'tom'},{'name':'john','age':20},{}]"; 3 4 JSONArray arr = JSONArray.fromObject(JSON_ARRAY); 5 System.out.println(arr); 6 7 for (int i = 0; i < arr.size(); i++) { 8 JSONObject obj = arr.getJSONObject(i); 9 System.out.println(obj.toString());10 }

输出：

[{"name":"tom"},{"name":"john","age":20},{}]
{"name":"tom"}
{"name":"john","age":20}
{}

5、构造一个json字符串：

1 JSONObject obj = new JSONObject(); 2 obj.put("name", "tom"); 3 obj.put("age", 19); 4 5 // 子对象 6 JSONObject objContact = new JSONObject(); 7 objContact.put("tel", "123456"); 8 objContact.put("email", "tom@test.com"); 9 obj.put("contact", objContact);1011 // 子数组对象12 JSONArray scoreArr = new JSONArray();13 JSONObject objEnglish = new JSONObject();14 objEnglish.put("course", "english");15 objEnglish.put("result", 100);16 objEnglish.put("level", "A");1718 JSONObject objMath = new JSONObject();19 objMath.put("course", "math");20 objMath.put("result", 50);21 objMath.put("level", "D");2223 scoreArr.add(objEnglish);24 scoreArr.add(objMath);2526 obj.put("score", scoreArr);2728 System.out.println(obj.toString());

输出：

{
    "score": [
        {
            "result": 100,
            "level": "A",
            "course": "english"
        },
        {
            "result": 50,
            "level": "D",
            "course": "math"
        }
    ],
    "contact": {
        "tel": "123456",
        "email": "tom@test.com"
    },
    "name": "tom",
    "age": 19
}