BroadcastReceiver

最新推荐文章于 2024-06-17 08:28:30 发布

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本文详细介绍了Android中的BroadcastReceiver组件，包括其使用方式、静态与动态注册的区别、以及普通广播与有序广播的特点。通过示例代码展示了如何实现不同类型的广播接收器。

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一、BroadcastReceiver概述

BroadcastReceiver是用来接收系统和应用的广播的一种组件

二、BroadcastReceiver使用方式

1、静态注册

静态注册是常驻型的,即当应用关闭,自定义BroadcastReceiver也会被系统调用

-新建自定义BroadcastReceiver继承自BroadcastReceiver

-重写onReceive()方法

-在AndroidManifest.xml中注册次BroadcastReceiver，并设置接收广播的action name,通常采用自定义BroadcastReceiver包名

-创建Intent对象,并通过setAction()设置与BroadcastReceiver匹配的action name

-sendBroadcast(intent)

<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>
    <receiver android:name=".MyReceiver">
        <intent-filter>
            <action android:name="com.example.lenovo.broadcastreceiver.TEST"/>
        </intent-filter>
    </receiver>
</application>

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {

        Log.i("msg" , intent.getStringExtra("msg"));

    }
}

public class MainActivity extends AppCompatActivity {

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

    public void doClick(View v){
        //以下两种写法均可
        Intent intent = new Intent("com.example.lenovo.broadcastreceiver.TEST");
        //intent.setAction("com.example.lenovo.broadcastreceiver.TEST");
        
        intent.putExtra("msg" , "已接收广播");
        sendBroadcast(intent);
    }
}

2、动态注册

-新建自定义BroadcastReceiver继承自BroadcastReceiver

-重写onReceive()方法

-创建IntentFilter对象,通常在Activity或Service中注册

-通过addAction()方法设置接收广播的action name

-通过registerReceiver()注册,参数分别为自定义BroadcastReceiver对象与IntentFilter对象

-创建Intent对象,并通过setAction()设置与BroadcastReceiver匹配的action name

-sendBroadcast(intent)

-通过unregisterReceiver()取消注册

public class MainActivity extends AppCompatActivity {

    private MyReceiver myReceiver = new MyReceiver();

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

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.lenovo.broadcastreceiver.TEST");
        registerReceiver(myReceiver , intentFilter);

    }

    public void doClick(View v){
        Intent intent = new Intent("com.example.lenovo.broadcastreceiver.TEST");
        intent.putExtra("msg" , "已接收广播");
        sendBroadcast(intent);

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(myReceiver);
    }
}

三、BroadcastReceiver种类

1、普通广播

-同级别接收先后顺序随机

-Receiver不能截断广播继续传播也不能处理广播

-同级别动态注册高于静态注册

2、有序广播

-同级别接收先后顺序随机

-同级别动态注册高于静态注册

-能截断广播继续传播,高级别BroadcasstReceiver收到广播后,可以决定是否截断广播

<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>
    <receiver android:name=".MyReceiver">
        <intent-filter android:priority="200">
            <action android:name="com.example.lenovo.broadcastreceiver.TEST"/>

        </intent-filter>
    </receiver>
    <receiver android:name=".MyReceiver2">
        <intent-filter android:priority="100">
            <action android:name="com.example.lenovo.broadcastreceiver.TEST"/>
        </intent-filter>
    </receiver>
</application>

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i("msg" , "MyReceiver:  " + intent.getStringExtra("msg"));
        //截断广播
        abortBroadcast();
    }
}

public class MyReceiver2 extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i("msg" , "MyReceiver2:  " + intent.getStringExtra("msg"));
    }
}

public class MainActivity extends AppCompatActivity {

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

    public void doClick(View v){
        Intent intent = new Intent("com.example.lenovo.broadcastreceiver.TEST");
        intent.putExtra("msg" , "RECEIVER已接收广播");
        sendOrderedBroadcast(intent , null);
    }
}

-Receiver可以处理广播

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i("msg" , intent.getStringExtra("msg"));
        Bundle bundle = new Bundle();
        bundle.putString("msg" , "@MyReceiver:   " + intent.getStringExtra("msg"));
        setResultExtras(bundle);
    }
}

public class MyReceiver2 extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.i("msg" , getResultExtras(true).getString("msg"));
    }
}