Android---四大组件之广播机制

作为android四大组件之一的广播,它注册时分为动态注册和静态注册。还有标准广播

动态注册Demo

配置文件中配置权限:

<uses-permission android:name="android.permission.INTERNET" />
    <!-- 访问系统网络状态权限 -->
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

public class MainActivity extends AppCompatActivity {
    private IntentFilter intentFilter;
    private NetworkChangeReceiver networkChangeReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        intentFilter=new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver=new NetworkChangeReceiver();
   //关键代码
        registerReceiver(networkChangeReceiver,intentFilter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
       // unregisterReceiver(networkChangeReceiver);
        Log.e("-----","onDestro");
    }

    class NetworkChangeReceiver extends BroadcastReceiver{

        @Override
        public void onReceive(Context context, Intent intent) {
            //获取系统服务类,专门用来管理网络连接的
            ConnectivityManager connectivityManager=
                    (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
            //判断是否有网络
            if (networkInfo!=null&&networkInfo.isAvailable()){
                Log.e("-----","有网络");
            }else {
                Log.e("-----","没有网络");
            }
        }
    }
}

动态注册的时候一定要在OnDestory中解除绑定才行

静态注册:

在AndroidManifest文件中配置如下的信息

 <receiver
    android:name=".MyReceiver" 
    android:enabled="true"    //是否启动这个广播接收器
    android:exported="true"   //是否允许接受本程序以外的广播/>

开机状态的广播

        <receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
            </intent-filter>
        </receiver>

自定义广播

无序广播:只需要以下配置 并且在Activity中通过Intent的sendBroadcast(intent); 方法即可

        <receiver
            android:name=".CustomBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.zc.myapplication.CustomBroadcastReceiver" />
            </intent-filter>
        </receiver>

有序广播: sendOrderedBroadcast(intent,null); 第二个参数是与权限相关的字符串一般设置成null就可以了
由于优先级比较高 在自定义的广播接收器Java代码中设置

        //广播截断
        abortBroadcast();

从而可以停止其他广播的接受

        <receiver
            android:name=".CustomBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter android:priority="100">
                <action android:name="com.zc.myapplication.CustomBroadcastReceiver" />
            </intent-filter>
        </receiver>

本地广播

本地广播主要使用的是一个LocalBroadcastManager来对广播进行管理

    private IntentFilter intentFilter;
    private LocalBroadcastManager localBroadcastManager;
    private LocalReceiver localReceiver;
    private Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_custom_broadcast);
        //获取实例
        localBroadcastManager=LocalBroadcastManager.getInstance(this);
        button= (Button) findViewById(R.id.mBtn);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent("com.zc.myapplication.LOCAL_BROADCAST");
                localBroadcastManager.sendBroadcast(intent);
            }
        });
        intentFilter=new IntentFilter();
        intentFilter.addAction("com.zc.myapplication.LOCAL_BROADCAST");
        localReceiver=new LocalReceiver();
        //注册本地广播监听器
        localBroadcastManager.registerReceiver(localReceiver,intentFilter);

本地广播只能是动态注册的.