监听SD卡状态变化

• 通过广播接收者来实现
• 一个广播可以接收多个

public class SDReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // 判断收到的是什么广播
        String action = intent.getAction();
        if ("android.intent.action.MEDIA_MOUNTED".equals(action)) {
            Toast.makeText(context, "准备就绪", Toast.LENGTH_SHORT).show();
        } else if ("android.intent.action.MEDIA_REMOVED".equals(action)) {
            Toast.makeText(context, "SD卡拔出", Toast.LENGTH_SHORT).show();
        } else if ("android.intent.action.MEDIA_UNMOUNTED".equals(action)) {
            Toast.makeText(context, "SD卡不可用", Toast.LENGTH_SHORT).show();
        }
    }
}

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

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

    <receiver
        android:name=".SDReceiver"
        android:enabled="true"
        android:exported="true">

        <intent-filter>
            <action android:name="android.intent.action.MEDIA_MOUNTED"></action>
            <action android:name="android.intent.action.MEDIA_REMOVED"></action>
            <action android:name="android.intent.action.MEDIA_UNMOUNTED"></action>

            <data android:scheme="file" />
        </intent-filter>
    </receiver>
</application>