Android 四大组件丨ContentProvider

ContentProvider 采用 Binder 机制，实现不同进程间共享数据与通信。本文模拟场景为：我拥有一张银行卡，家里收入归我统一管理！媳妇的收益转账给我，媳妇的零花钱由我转出，啧啧啧，我再做会儿梦！

应用 A

创建 ContentProvider

/**
 * @des ContentProvider 事件接收类
 * @author liyongli 20191108
 * */
public class MoneyProvider extends ContentProvider {

    // 定义 AUTHORITY （唯一路径）
    public static final String AUTHORITY = "com.myprovider.test.moneyprovider";

    // 定义过滤器
    private static UriMatcher uriMatcher;

    // 实例化本类时时调用
    static {
        uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        uriMatcher.addURI(AUTHORITY, "family", 0);
    }

    @Override
    public boolean onCreate() {
        return false;
    }

    @Nullable
    @Override
    public Uri insert(Uri uri,  @Nullable ContentValues values) {
        Log.e("==", "媳妇打钱了！");
        return null;
    }

    @Override
    public int delete(Uri uri,  @Nullable String selection,  @Nullable String[] selectionArgs) {
        Log.e("==", "媳妇要零花钱（全要）！");
        return 0;
    }

    @Override
    public int update(Uri uri,  @Nullable ContentValues values,  @Nullable String selection,  @Nullable String[] selectionArgs) {
        Log.e("==", "媳妇要零花钱（不全要）！");
        return 0;
    }

    
    @Nullable
    @Override
    public Cursor query(Uri uri,  @Nullable String[] projection,  @Nullable String selection,  @Nullable String[] selectionArgs,  @Nullable String sortOrder) {
        Log.e("==", "媳妇要查账！");
        return null;
    }

    @Nullable
    @Override
    public String getType(Uri uri) {
        return null;
    }
}

注册 ContentProvider

        <!--数据共享组件注册-->
        <provider
            android:name="com.myprovider.test.MoneyProvider"
            android:authorities="com.myprovider.test.moneyprovider"
            android:enabled="true"
            android:exported="true">
        </provider>

应用 B

Activity

/**
 * @des ContentProvider 事件发起类
 * @author liyongli 20191108
 * */
public class MainActivity extends AppCompatActivity {

    public static final String AUTHORITY = "com.myprovider.test.moneyprovider";

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

        findViewById(R.id.add).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Uri uri = Uri.parse("content://" + AUTHORITY +"/money");
                ContentValues values = new ContentValues();
                getContentResolver().insert(uri, values);
            }
        });

        findViewById(R.id.delete).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Uri uri = Uri.parse("content://" + AUTHORITY +"/money");
                getContentResolver().delete(uri,"", new String[]{""});
            }
        });

        findViewById(R.id.update).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Uri uri = Uri.parse("content://" + AUTHORITY +"/money");
                ContentValues values = new ContentValues();
                getContentResolver().update(uri,values,"",new String[]{""});
            }
        });

        findViewById(R.id.query).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Uri uri = Uri.parse("content://" + AUTHORITY +"/money");
                Cursor cursor = getContentResolver().query(uri,null,null,null,null);
            }
        });

    }

}

XML

<?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"
    android:paddingTop="200dp"
    tools:context=".MainActivity">

        <Button
            android:id="@+id/add"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="打钱"/>

        <Button
            android:id="@+id/delete"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="要零花钱（全要）"/>

        <Button
            android:id="@+id/update"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="要零花钱（不全要）"/>

        <Button
            android:id="@+id/query"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="查账"/>

</LinearLayout>

运行效果

先运行应用 A，再运行应用 B

点击应用 A 按钮后，应用 B 控制台输出如下：

2019-11-08 17:36:31.053 E/==: 媳妇打钱了！
2019-11-08 17:36:31.685 E/==: 媳妇要零花钱（全要）！
2019-11-08 17:36:32.161 E/==: 媳妇要零花钱（不全要）！
2019-11-08 17:36:32.714 E/==: 媳妇要查账！