java解析json字符串详解（两种方法）

private void parseJSONWithJSONObject(String JsonData) {
    try
    {
        JSONArray jsonArray = new JSONArray(jsonData);
        for (int i=0; i < jsonArray.length(); i++)    {
            JSONObject jsonObject = jsonArray.getJSONObject(i);
            String id = jsonObject.getString("id");
            String name = jsonObject.getString("name");
            String version = jsonObect.getString("version");

            System.out.println("id" + id + ";name" + name + ";version" + version);
        }
    }
    catch (Exception e)
    {
        e.printStackTrace();
    }

[
    {
        "id": 1580615,"name": "皮的嘛","packageName": "com.renren.mobile.android","iconUrl": "app/com.renren.mobile.android/icon.jpg","stars": 2,"size": 21803987,"downloadUrl": "app/com.renren.mobile.android/com.renren.mobile.android.apk","des": "2011-2017 你的铁头娃一直在这儿。中国最大的实名制SNS网络平台，嫩头青"
    },{
        "id": 1540629,"name": "不存在的","packageName": "com.ct.client","iconUrl": "app/com.ct.client/icon.jpg","size": 4794202,"downloadUrl": "app/com.ct.client/com.ct.client.apk","des": "斗鱼271934走过路过不要错过，这里有最好的鸡儿"
    }
]
 JSONArray jsonArray=new JSONArray(json);
            for(int i=0;i<jsonArray.length();i++){
                JSONObject object=jsonArray.getJSONObject(i);
                String id=object.getString("id");
                String name=object.getString("name");
                String packageName=object.getString("packageName");
                String iconUrl = object.getString("iconUrl");
                double stars=Double.parseDouble(object.getString("stars"));
                String size=object.getString("size");
                String downloadUrl = object.getString("downloadUrl");
                String des = object.getString("des");
               //其他操作
               ....
            }

 {
            "id": 1525490,"name": "有缘网","packageName": "com.youyuan.yyhl","iconUrl": "app/com.youyuan.yyhl/icon.jpg","stars": 4,"size": 3876203,"downloadUrl": "app/com.youyuan.yyhl/com.youyuan.yyhl.apk","des": "产品介绍：有缘是时下最受大众单身男女亲睐的婚恋交友软件。有缘网专注于通过轻松、"
        }
 JSONObject object = new JSONObject(json);
            long id = object.getLong("id");
            String name = object.getString("name");
            String packageName = object.getString("packageName");
            String iconUrl = object.getString("iconUrl");
            float stars = Float.parseFloat(object.getString("stars"));
            long size = object.getLong("size");
            String downloadUrl = object.getString("downloadUrl");
            String des = object.getString("des");

private void parseJSONWithGSON(String JsonData) {
    Gson gson = new Gson();
    List<Student > applist = gson.fromJson(jsonData,new TypeToken<List<App>>() {}.getType());
    for(Student student: studentlist) {
     
    }
}

public class Student {

    private String name;
    private int age;
    private boolean sex;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public boolean isSex() {
        return sex;
    }

    public void setSex(boolean gender) {
        this.sex = gender;
    }

    @Override
    public String toString() {
        return "Student [name=" + name + ",age=" + age + ",sex=" + sex + "]";
    }

}

public class DemoFormat {

    // 将 java 对象 格式化为 Json 字符串.
    public static void main(String[] args) {

        Student stu = new Student();
        stu.setName("张三");
        stu.setAge(18);
        stu.setSex(true);

        Gson gson = new Gson();
        //toJson方法参数即一个javabean。返回值即一个json字符串
        String json = gson.toJson(stu);
        //打印为 {"name":"张三","age":18,"sex":true} 
        System.out.println(json);
    }
}

public class DemoFormat {

    // 将 Json 字符串. 格式化为 java对象.
    public static void main(String[] args) {
        String json = "{‘name‘:‘张三‘,‘age‘:18,‘sex‘:true}";
        Gson gson = new Gson();
        // 将json 转化成 java 对象  
        //fromJson方法。参数一是json字符串。参数二是要转换的javabean
        //该javabean的字段名必须与json的key名字完全对应才能被正确解析。
        Student stu = gson.fromJson(json,Student.class);
    }
}

json:

        [{‘name‘:‘二阳‘,‘sex‘:true},{‘name‘:‘小2阳‘,‘age‘:19,‘sex‘:false},{‘name‘:‘小3马‘,‘age‘:20,{‘name‘:‘小4梦‘,‘age‘:21,{‘name‘:‘小5莲‘,‘age‘:22,‘sex‘:true}]

 Gson gson = new Gson();
        // 将 json 转化 成 List泛型
        List<Student> stus = gson.fromJson(json,new TypeToken<List<Student>>() {}.getType());

{
    "picture": "image/home01.jpg","list": [
        {
            "id": 1525490,"name": "aaa"
        },{
             "id": 1525490,"name": "bbb"
        }
         ]
}

public class Infos{
    String  picture;
    List<Name>  list;

class Name{
  String id;
  String name
}
//所有的setter方法此处省略,其实如果合用的是AS开发可以直接使用工具Gsonfomat一键生成javabean很方便
}

  {‘flag‘:true,‘data‘:{‘name‘:‘张三‘,‘sex‘:true}} 

1. 获得 解析者

        JsonParser parser = new JsonParser();

2. 获得 根节点元素

        JsonElement element = parser.parse(json);


3. 根据 文档判断根节点属于 什么类型的 Gson节点对象


        // 假如文档 显示 根节点 为对象类型  对象类型即 {}表示。[]表示为数组类型。
        // 获得 根节点 的实际 节点类型
        JsonObject root = element.getAsJsonObject();


4. 取得 节点 下 的某个节点的 value

        // 获得 flag 节点的值,flag 节点为基本数据节点
        JsonPrimitive flagJson = root.getAsJsonPrimitive("flag");
        // 基本节点取值
        boolean flag = flagJson.getAsBoolean();

        // 获得 data 节点的值，data 节点为Object数据节点
        JsonObject dataJson = root.getAsJsonObject("data");
        // 将节点上的数据转换为对象
        Student stu = new Gson().fromJson(dataJson,Student.class);