Android广播demo（系统广播，自定义广播）

1 系统广播demo

1.1 BootReceiver 的广播接收器类：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;public class BootReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// 检查广播动作是否是设备启动完成if (Intent.ACTION_BOOT_COMPLETED.equals(intent.getAction())) {// 在设备启动完成时显示 Toast 消息Toast.makeText(context, "设备已启动完成！", Toast.LENGTH_SHORT).show();}}
}

1.2 AndroidManifest.xml 文件中声明广播接收器，并指定接收 BOOT_COMPLETED 广播

<receiverandroid:name=".BootReceiver"android:enabled="true"android:exported="false"><intent-filter><action android:name="android.intent.action.BOOT_COMPLETED" /><category android:name="android.intent.category.DEFAULT" /></intent-filter>
</receiver>

1.3 应用程序已经请求了 RECEIVE_BOOT_COMPLETED 权限

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

1.4 设备启动完成时，系统会发送 BOOT_COMPLETED 广播，而我们的广播接收器会接收到该广播并触发 onReceive() 方法，从而显示一个 Toast 消息

2 自定义广播demo

2.1 发送广播的活动

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;public class SendBroadcastActivity extends AppCompatActivity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_send_broadcast);Button sendButton = findViewById(R.id.sendButton);sendButton.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {// 创建一个自定义广播 IntentIntent customBroadcastIntent = new Intent("com.example.androiddemo.CUSTOM_BROADCAST");// 添加额外的数据customBroadcastIntent.putExtra("message", "这是自定义广播的消息！");// 发送广播sendBroadcast(customBroadcastIntent);}});}
}

2.2 发送广播的活动布局文件（activity_send_broadcast.xml）中，添加一个按钮

<Buttonandroid:id="@+id/sendButton"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="发送自定义广播" />

2.3 AndroidManifest.xml 中声明了这两个活动

<activity android:name=".SendBroadcastActivity" />
<activity android:name=".ReceiveBroadcastActivity" />

2.4 接收广播的活动

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;public class ReceiveBroadcastActivity extends AppCompatActivity {private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {// 从广播中获取消息String message = intent.getStringExtra("message");// 显示消息Toast.makeText(context, message, Toast.LENGTH_SHORT).show();}};@Overrideprotected void onResume() {super.onResume();// 注册广播接收器registerReceiver(broadcastReceiver, new IntentFilter("com.example.androiddemo.CUSTOM_BROADCAST"));}@Overrideprotected void onPause() {super.onPause();// 取消注册广播接收器unregisterReceiver(broadcastReceiver);}
}