【Android】Android中广播的基本使用

接受系统广播

动态注册

在Java代码中指定IntentFilter，然后想监听什么广播就添加对应的Action。动态注册的广播，一定要调用unregisterReceiver()方法取消注册。

下面用动态注册监听网络变化

在AndroidManifest.xml中添加权限：

Activity的Java代码：

publicclassMainActivityextendsAppCompatActivity{privateIntentFilter intentFilter;privateNetworkChangeReceiver networkChangeReceiver;@OverrideprotectedvoidonCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//动态接受网络变化的广播接收器intentFilter =newIntentFilter();        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");        networkChangeReceiver =newNetworkChangeReceiver();        registerReceiver(networkChangeReceiver, intentFilter);    }@OverrideprotectedvoidonDestroy() {super.onDestroy();//取消动态网络变化广播接收器的注册unregisterReceiver(networkChangeReceiver);    }//自定义接受网络变化的广播接收器class NetworkChangeReceiver extends BroadcastReceiver {@OverridepublicvoidonReceive(Context context, Intent intent) {            ConnectivityManager connectionManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);            NetworkInfo networkInfo = connectionManager.getActiveNetworkInfo();if(networkInfo !=null&& networkInfo.isAvailable()) {                Toast.makeText(context,"network is available", Toast.LENGTH_SHORT).show();            }else{                Toast.makeText(context,"network is unavailable", Toast.LENGTH_SHORT).show();            }        }    }}

静态注册

动态注册需要程序启动之后才能接收广播，静态广播就弥补了这个短板。在AndroidManifest中指定IntentReceiver就可以在程序未启动的情况下接收到广播

下面用静态注册接受开机广播

新建一个广播接收器

publicclassMyBroadcastReceiverextendsBroadcastReceiver{@OverridepublicvoidonReceive(Context context, Intent intent) {        Toast.makeText(context,"received in MyBroadcastReceiver", Toast.LENGTH_SHORT).show();    }}

在AndroidManifest.xml中添加权限、注册广播接收器和添加Action

发送广播

发送标准广播

接收器的Java代码：

publicclassMyBroadcastReceiverextendsBroadcastReceiver{@OverridepublicvoidonReceive(Context context, Intent intent) {        Toast.makeText(context,"received in MyBroadcastReceiver", Toast.LENGTH_SHORT).show();    }}

接收器的注册代码：

Activity的Java代码

publicclassMainActivityextendsAppCompatActivity{privateButton button;@OverrideprotectedvoidonCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//发送自定义广播button = (Button) findViewById(R.id.button);        button.setOnClickListener(newView.OnClickListener() {@OverridepublicvoidonClick(View v) {                Intent intent =newIntent("com.example.broadcasttest.MY_BROADCAST");                sendBroadcast(intent);            }        });    }@OverrideprotectedvoidonDestroy() {super.onDestroy();//取消动态网络变化广播接收器的注册unregisterReceiver(networkChangeReceiver);    } }

发送有序广播

发送有序广播的方法：

sendOrderedBroadcast(intent,null);

设置广播接收器的先后顺序，在AndroidManifest.xml中receiver的intent-filter的priority属性，优先级可选值：-1000~1000

android:priority="100"

使用本地广播

主要是用LocalBroadcastManager来对广播进行管理，提供了发送广播和注册广播接收器的方法如下：

LocalBroadcastManager.getInstance()获得实例

~.registerReceiver()注册广播

~.sendBroadcast()发送广播

~.unregisterReceiver()取消广播

注意事项：

本地广播无法通过静态注册来接收，相比系统全局广播更加高效

在广播中启动活动需要添加FLAG_ACTIVITY_NEW_TASK的标记

在广播中弹出AlertDialog需要添加TYPE_SYSTEM_ALERT

Java代码：

publicclassMainActivityextendsAppCompatActivity{privateIntentFilter intentFilter;privateLocalReceiver localReceiver;privateLocalBroadcastManager localBroadcastManager;@OverrideprotectedvoidonCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//得到本地广播管理器的实例localBroadcastManager = LocalBroadcastManager.getInstance(this);//动态注册本地广播接收器intentFilter =newIntentFilter();        intentFilter.addAction("com.example.broadcasttest.LOCAL_BROADCAST");        localReceiver =newLocalReceiver();        localBroadcastManager.registerReceiver(localReceiver, intentFilter);//发送本地广播Button button = (Button) findViewById(R.id.button);        button.setOnClickListener(newView.OnClickListener() {@OverridepublicvoidonClick(View v) {                Intent intent =newIntent("com.example.broadcasttest.LOCAL_BROADCAST");                localBroadcastManager.sendBroadcast(intent);            }        });    }@OverrideprotectedvoidonDestroy() {super.onDestroy();//取消动态网络变化广播接收器的注册localBroadcastManager.unregisterReceiver(localReceiver);    }    class LocalReceiver extends BroadcastReceiver {@OverridepublicvoidonReceive(Context context, Intent intent) {            Toast.makeText(context,"received local broadcast", Toast.LENGTH_SHORT).show();        }    }}