// Gson支持包的导入
implementation ''com.google.code.gson:gson:2.6.2''

{
    "name":"李四",
    "age":99,
    "hobby":"爱好是练习截拳道"
}

[
    {
        "name":"君君",
        "age":89,
        "sex":"男"
    },
    {
        "name":"小君",
        "age":99,
        "sex":"女"
    },
    {
        "name":"大君",
        "age":88,
        "sex":"男"
    }
]

package liudeli.mynetwork01.entity;

/**
 * 定义一个Bean
 * 定义的name/age/hobby 必须要和JSON数据里面的一模一样
 * {
 *     "name":"李四",
 *     "age":99,
 *     "hobby":"爱好是练习截拳道"
 * }
 */
public class Student2 {

    private String name;
    private int age;
    private String hobby;

    public Student2(String name, int age, String hobby) {
        this.name = name;
        this.age = age;
        this.hobby = hobby;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name=''" + name + ''\'''' +
                ", age=" + age +
                ", hobby=''" + hobby + ''\'''' +
                ''}'';
    }
}

package liudeli.mynetwork01.entity;

/**
 * 定义一个Bean
 * 定义的name/age/sex 必须要和JSON数据里面的一模一样
 *
 * [
 *     {
 *         "name":"君君",
 *         "age":89,
 *         "sex":"男"
 *     },
 *     {
 *         "name":"小君",
 *         "age":99,
 *         "sex":"女"
 *     },
 *     {
 *         "name":"大君",
 *         "age":88,
 *         "sex":"男"
 *     }
 * ]
 */
public class Student {

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

    public Student(String name, int age, String sex) {
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

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

package liudeli.mynetwork01;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.util.List;

import liudeli.mynetwork01.entity.Student;
import liudeli.mynetwork01.entity.Student2;

public class GsonAnalyzeJSONActivity extends Activity {

    private final String TAG = GsonAnalyzeJSONActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_gson_analyze);
    }

    /**
     * Gson解析JSON对象
     * {
     *     "name":"李四",
     *     "age":99,
     *     "hobby":"爱好是练习截拳道"
     * }
     */
    public void gonsAnalyzeJSONObject(View view) {
       String jsonData = readFile("pottingJSON1");
       // Log.d(TAG, "jsonData:" + jsonData);

       Gson gson = new Gson();
       Student2 student2 = gson.fromJson(jsonData, Student2.class);
       Log.d(TAG, "gonsAnalyzeJSONObject 解析后的结果:" + student2.toString());
    }

    /**
     * Gson解析JSON数组
     * [
     *     {
     *         "name":"君君",
     *         "age":89,
     *         "sex":"男"
     *     },
     *     {
     *         "name":"小君",
     *         "age":99,
     *         "sex":"女"
     *     },
     *     {
     *         "name":"大君",
     *         "age":88,
     *         "sex":"男"
     *     }
     * ]
     * @param view
     */
    public void gonsAnalyzeJSONArray(View view) {
        String jsonData = readFile("pottingJSONArray1");
        // Log.d(TAG, "jsonData:" + jsonData);

        Gson gson = new Gson();

        /**
         * TypeToken<List<需要映射的Bean对象>>(){}.getType()
         */
        List<Student> list = gson.fromJson(jsonData, new TypeToken<List<Student>>(){}.getType()); // 参数二：需要指定类型，类型来决定解析的集合

        for (Student student: list) {
            Log.d(TAG, "gonsAnalyzeJSONArray 解析后的结果:" + student.toString());
        }

    }

    /**
     * 读取文件里面的字符串
     * @param fileName
     * @return
     */
    private String readFile(String fileName) {
        String result = null;
        try {
            InputStream inputStream = openFileInput(fileName);

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            byte[] bytes = new byte[inputStream.available()];

            inputStream.read(bytes);

            baos.write(bytes, 0,bytes.length);

            result = new String(baos.toByteArray());

            baos.close();
            inputStream.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Gson解析JSON对象"
        android:onClick="gonsAnalyzeJSONObject"
        />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Gson解析JSON数组"
        android:onClick="gonsAnalyzeJSONArray"
        />

</LinearLayout>

{
    "name":"李四",
    "age":99,
    "hobby":"爱好是练习截拳道"
}

{
    "student":{
        "name":"李四",
        "age":99,
        "hobby":"爱好是练习截拳道"
    }
}

{
    "student":{
        "name":"李四",
        "age":99,
        "hobby":"爱好是练习截拳道",
        "dog":{
            "name":"阿黄",
            "age":77,
            "sex":"母"
        }
    }
}

[
    {
        "name":"君君",
        "age":89,
        "sex":"男"
    },
    {
        "name":"小君",
        "age":99,
        "sex":"女"
    },
    {
        "name":"大君",
        "age":88,
        "sex":"男"
    }
]

{
    "person":[
        {
            "name":"君君",
            "age":89,
            "sex":"男"
        },
        {
            "name":"小君",
            "age":99,
            "sex":"女"
        },
        {
            "name":"大君",
            "age":88,
            "sex":"男"
        }
    ]
}

package liudeli.mynetwork01;

import android.app.Activity;
import android.os.Bundle;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;

import org.json.JSONArray;
import org.json.JSONObject;

import java.io.InputStream;

public class AnalyzeJSONActivity extends Activity {

    private final String TAG = AnalyzeJSONActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_analyze_json);
    }

    /**
     * 解析JSON对象
     * {
     *     "name":"李四",
     *     "age":99,
     *     "hobby":"爱好是练习截拳道"
     * }
     * @param view
     */
    public void analyzeJSON1(View view) {

        String result =  readFile("pottingJSON1");
        // Log.d(TAG, "result:" + result);

        try{
           JSONObject jsonObject = new JSONObject(result);
            /**
             * 为什么要使用jsonObject.optString， 不使用jsonObject.getString
             * 因为jsonObject.optString获取null不会报错
             */
           String name = jsonObject.optString("name", null);
           int age = jsonObject.optInt("age", 0);
           String hobby = jsonObject.optString("hobby", null);

            // 日志打印结果：
           Log.d(TAG, "analyzeJSON1解析的结果：name:" + name + " age:" + age + " hobby:" + hobby);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解析JSON对象-带Key
     * {
     *     "student":{
     *         "name":"李四",
     *         "age":99,
     *         "hobby":"爱好是练习截拳道"
     *     }
     * }
     * @param view
     */
    public void analyzeJSON2(View view) {
        String result =  readFile("pottingJSON2");
        // Log.d(TAG, "result:" + result);

        try{
            // 整个最大的JSON对象
            JSONObject jsonObjectALL = new JSONObject(result);
            /**
             * 为什么要使用jsonObject.optString， 不使用jsonObject.getString
             * 因为jsonObject.optString获取null不会报错
             */
            String student = jsonObjectALL.optString("student", null);

            if (!TextUtils.isEmpty(student)) {
                JSONObject jsonObject = new JSONObject(student);
                String name = jsonObject.optString("name", null);
                int age = jsonObject.optInt("age", 0);
                String hobby = jsonObject.optString("hobby", null);

                // 日志打印结果：
                Log.d(TAG, "analyzeJSON2解析的结果：name:" + name + " age:" + age + " hobby:" + hobby);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解析JSON对象-嵌套对象
     * {
     *     "student":{
     *         "name":"李四",
     *         "age":99,
     *         "hobby":"爱好是练习截拳道",
     *         "dog":{
     *             "name":"阿黄",
     *             "age":77,
     *             "sex":"母"
     *         }
     *     }
     * }
     * @param view
     */
    public void analyzeJSON3(View view) {
        String result =  readFile("pottingJSON3");
        // Log.d(TAG, "result:" + result);

        try{
            // 整个最大的JSON对象
            JSONObject jsonObjectALL = new JSONObject(result);
            /**
             * 为什么要使用jsonObject.optString， 不使用jsonObject.getString
             * 因为jsonObject.optString获取null不会报错
             */
            String student = jsonObjectALL.optString("student", null);

            if (!TextUtils.isEmpty(student)) {
                JSONObject jsonObject = new JSONObject(student);
                String name = jsonObject.optString("name", null);
                int age = jsonObject.optInt("age", 0);
                String hobby = jsonObject.optString("hobby", null);

                // 以下是dog JSON 对象相关的解析

                String dogStr = jsonObject.optString("dog", null);
                // 定义dog的JSON对象
                JSONObject dogJSONObject = new JSONObject(dogStr);
                String dogName = dogJSONObject.optString("name", null);
                int dogAge = dogJSONObject.optInt("age", 0);
                String dogSex = dogJSONObject.optString("sex", null);

                // 日志打印结果：
                Log.d(TAG, "analyzeJSON3解析的结果：name:" + name + " age:" + age + " hobby:" + hobby + "\n"
                                 + "dogName:" + dogName + " dogAge:" + dogAge + " dogSex:" + dogSex);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解析JSON数组
     * [
     *     {
     *         "name":"君君",
     *         "age":89,
     *         "sex":"男"
     *     },
     *     {
     *         "name":"小君",
     *         "age":99,
     *         "sex":"女"
     *     },
     *     {
     *         "name":"大君",
     *         "age":88,
     *         "sex":"男"
     *     }
     * ]
     * @param view
     */
    public void analyzeJSONArray1(View view) {
        String result =  readFile("pottingJSONArray1");
        // Log.d(TAG, "result:" + result);

        try{
            // 整个最大的JSON数组
            JSONArray jsonArray = new JSONArray(result);
            Log.d(TAG, "analyzeJSONArray1 jsonArray:" + jsonArray);
            // [{"name":"君君","age":89,"sex":"男"},{"name":"小君","age":99,"sex":"女"},{"name":"大君","age":88,"sex":"男"}]

            for (int i = 0; i < jsonArray.length(); i++) {
                // JSON数组里面的具体-JSON对象
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String name = jsonObject.optString("name", null);
                int age = jsonObject.optInt("age", 0);
                String sex = jsonObject.optString("sex", null);

                // 日志打印结果：
                Log.d(TAG, "analyzeJSONArray1 解析的结果：name" + name + " age:" + age + " sex:" + sex);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 解析JSON数组-带Key
     * {
     *     "person":[
     *         {
     *             "name":"君君",
     *             "age":89,
     *             "sex":"男"
     *         },
     *         {
     *             "name":"小君",
     *             "age":99,
     *             "sex":"女"
     *         },
     *         {
     *             "name":"大君",
     *             "age":88,
     *             "sex":"男"
     *         }
     *     ]
     * }
     * @param view
     */
    public void analyzeJSONArray2(View view) {
        String result =  readFile("pottingJSONArray2");
        // Log.d(TAG, "result:" + result);

        try{
            /**
             * JSON数组在牛逼，一旦有了 key person 这样的标记，就必须先是个 JSON对象
             * 最外层的JSON对象，最大的哪个 { ... }
             */
            JSONObject jsonObjectALL = new JSONObject(result);

            // 通过标识(person)，获取JSON数组
            JSONArray jsonArray = jsonObjectALL.getJSONArray("person");

            Log.d(TAG, "analyzeJSONArray1 jsonArray:" + jsonArray);
            // [{"name":"君君","age":89,"sex":"男"},{"name":"小君","age":99,"sex":"女"},{"name":"大君","age":88,"sex":"男"}]

            for (int i = 0; i < jsonArray.length(); i++) {
                // JSON数组里面的具体-JSON对象
                JSONObject jsonObject = jsonArray.getJSONObject(i);
                String name = jsonObject.optString("name", null);
                int age = jsonObject.optInt("age", 0);
                String sex = jsonObject.optString("sex", null);

                // 日志打印结果：
                Log.d(TAG, "analyzeJSONArray2 解析的结果：name" + name + " age:" + age + " sex:" + sex);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 读取文件里面的字符串
     * @param fileName
     * @return
     */
    private String readFile(String fileName) {
        String result = null;
        try {
            InputStream inputStream = openFileInput(fileName);

            byte[] bytes = new byte[inputStream.available()];
            inputStream.read(bytes);
            result = new String(bytes);

            inputStream.close();

        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 定义一个Bean
     */
    /*class Student {
        private String name;
        private int age;
        private String hobby;

        public Student(String name, int age, String hobby) {
            this.name = name;
            this.age = age;
            this.hobby = hobby;
        }

        @Override
        public String toString() {
            return "Student{" +
                    "name=''" + name + ''\'''' +
                    ", age=" + age +
                    ", hobby=''" + hobby + ''\'''' +
                    ''}'';
        }
    }*/
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解析JSON对象"
            android:onClick="analyzeJSON1"
            android:layout_weight="1"
            />


        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解析JSON对象-带Key"
            android:onClick="analyzeJSON2"
            android:layout_weight="1"
            />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解析JSON对象-嵌套对象"
            android:onClick="analyzeJSON3"
            android:layout_weight="1"
            />


    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解析JSON数组"
            android:onClick="analyzeJSONArray1"
            android:layout_weight="1"
            />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="解析JSON数组-带Key"
            android:onClick="analyzeJSONArray2"
            android:layout_weight="1"
            />

    </LinearLayout>

</LinearLayout>