JSON và web API trong lập trình Android cơ bản

apply plugin: 'com.android.application'

android {
    compileSdkVersion 24
    buildToolsVersion "24.0.2"
    defaultConfig {
        applicationId "com.howkteam.jsonexample"
        minSdkVersion 13
        targetSdkVersion 24
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:24.2.1'
    testCompile 'junit:junit:4.12'

    compile 'com.android.support:recyclerview-v7:24.2.1'
    compile 'com.squareup.okhttp3:okhttp:3.4.1'
    compile 'com.squareup.moshi:moshi:1.2.0'
    compile 'com.squareup.picasso:picasso:2.5.2'
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

package com.howkteam.jsonexample;

public class User {
    public String login;
    public int id;
    public String avatar_url;
}
1
2
3
4
5
6
7
8

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:padding="8dp">

    <ImageView
        android:id="@+id/iv_avatar"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"/>

    <TextView
        android:id="@+id/tv_login_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_toRightOf="@id/iv_avatar"/>

    <TextView
        android:id="@+id/tv_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv_login_name"
        android:layout_toRightOf="@id/iv_avatar"/>

</RelativeLayout>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

package com.howkteam.jsonexample;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.squareup.picasso.Picasso;

import java.util.List;

public class UserAdapter extends RecyclerView.Adapter<UserAdapter.UserItemViewHolder> {
    private List<User> users;
    private Context context;

    public UserAdapter(List<User> users, Context c) {
        this.users = users;
        this.context = c;
    }

    @Override
    public int getItemCount() {
        return users.size();
    }

    @Override
    public UserItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item_user, parent, false);

        return new UserItemViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(UserItemViewHolder holder, int position) {
        User u = users.get(position);
        Picasso.with(context)
                .load(u.avatar_url)
                .into(holder.ivAvatar);
        holder.tvLoginName.setText(u.login);
        holder.tvId.setText(String.valueOf(u.id));
    }

    public static class UserItemViewHolder extends RecyclerView.ViewHolder {
        public TextView tvLoginName;
        public TextView tvId;
        public ImageView ivAvatar;

        public UserItemViewHolder(View itemView) {
            super(itemView);
            tvLoginName = (TextView) itemView.findViewById(R.id.tv_login_name);
            tvId = (TextView) itemView.findViewById(R.id.tv_id);
            ivAvatar = (ImageView) itemView.findViewById(R.id.iv_avatar);
        }
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.howkteam.jsonexample.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv_users"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</RelativeLayout>

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

package com.howkteam.jsonexample;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;

import com.squareup.moshi.JsonAdapter;
import com.squareup.moshi.Moshi;
import com.squareup.moshi.Types;

import java.io.IOException;
import java.lang.reflect.Type;
import java.util.List;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Khởi tạo RecyclerView.
        final RecyclerView rvUsers = (RecyclerView) findViewById(R.id.rv_users);
        rvUsers.setLayoutManager(new LinearLayoutManager(this));

        // Khởi tạo OkHttpClient để lấy dữ liệu.
        OkHttpClient client = new OkHttpClient();

        // Khởi tạo Moshi adapter để biến đổi json sang model java (ở đây là User)
        Moshi moshi = new Moshi.Builder().build();
        Type usersType = Types.newParameterizedType(List.class, User.class);
        final JsonAdapter<List<User>> jsonAdapter = moshi.adapter(usersType);

        // Tạo request lên server.
        Request request = new Request.Builder()
                .url("https://api.github.com/users")
                .build();

        // Thực thi request.
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                Log.e("Error", "Network Error");
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                
                // Lấy thông tin JSON trả về. Bạn có thể log lại biến json này để xem nó như thế nào.
                String json = response.body().string();
                final List<User> users = jsonAdapter.fromJson(json);
                
                // Cho hiển thị lên RecyclerView.
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        rvUsers.setAdapter(new UserAdapter(users, MainActivity.this));
                    }
                });
            }
        });
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.howkteam.jsonexample">

    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24