Android 四大组件之BroadcastReceiver

程序员文章站 2022-05-09 20:53:20

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一、什么是广播

在Android中，Broadcast是一种广泛应用在应用程序之间传输信息的机制，通过Intent携带我们要传送的数据。

二、广播应用场景

1.同一个app中，多进程间不同组件的消息传递

2.不同app之间的组件之间通信

三、广播分类

1.普通广播（Normal Broadcast）

2.系统广播（System Broadcast）

3.有序广播（Ordered Broadcast）

4.App应用内广播（Local Broadcast）

四、实现BroadcastReceiver

1.静态注册:常驻广播

①创建一个类继承BroadcastReceiver

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
     String action = intent.getAction();
        if (action.equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
            Log.d("aaa", "网络状态已经改变");
            ConnectivityManager     connectivityManager = (ConnectivityManager) context
                    .getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo info = connectivityManager.getActiveNetworkInfo();
            if (info != null && info.isAvailable()) {
                String name = info.getTypeName();
                Log.d("aaa", "当前网络名称：" + name);
            } else {
                Log.d("aaa", "没有可用网络");
            }
        }
    }
}

②在清单文件中注册（记得加上权限）

 <receiver android:name=".MyReceiver"
            >
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
</receiver>

③断开网络，然后连接网络结果如图

Android 四大组件之BroadcastReceiver

2.动态注册：跟随Activity生命周期

①创建广播类HomePressReceiver（监听home的点击）

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;



public class HomePressReceiver extends BroadcastReceiver {

    private String TAG="HomePressReceiver";
    private static final String SYSTEM_DIALOG_REASON_KEY = "reason";
//    private static final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";
    private static final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if(null != action && !"".equals(action) && action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {
            String reason = intent.getStringExtra(SYSTEM_DIALOG_REASON_KEY);
            if(null != reason && !"".equals(reason)) {
                if(reason.equals(SYSTEM_DIALOG_REASON_HOME_KEY)) {// �̰�home��
                    Log.e(TAG,"点击HOME");
                } 
            }
        }
    }

}

② 在Activity中注册广播，并在activity销毁是反注册


import android.content.Intent;
import android.content.IntentFilter;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
    private HomePressReceiver homePressReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        homePressReceiver = new HomePressReceiver();
        //注册动态广播
        registerReceiver(homePressReceiver, new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS));
    }
    @Override
    protected void onDestroy() {

        unregisterHomeKeyReceiver();
        super.onDestroy();

    }
    //反注册
    private  void unregisterHomeKeyReceiver() {
        if (null != homePressReceiver) {
            unregisterReceiver(homePressReceiver);
        }
    }
}

③运行程序，点击home键效果如图

Android 四大组件之BroadcastReceiver