系统开始重启会发送开机重启广播，电量低的时候会发送电量低的广播，广播注册有2种:系统说明文件xml注册和Java代码注册，前者是静态注册(全局注册)后者是动态注册（依赖于当时组建，组件销毁就收不到广播了）。

package com.sxt.day07_04;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;public class MainActivity extends Activity {    MyReceiver2 mReceiver;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        registerReceiver();        setListener();    }    private void setListener() {        sendBroadcast1ClickListener();        sendBroadcast2ClickListener();    }    private void sendBroadcast2ClickListener() {        findViewById(R.id.btnSendBroadcast_2).setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View v) {                Intent intent=new Intent("com.sxt.day07_04.MyReceiver2");//                intent.putExtra("key", "hello android!");                sendBroadcast(intent);            }        });    }    private void sendBroadcast1ClickListener() {        findViewById(R.id.btnSendBroadcast_1).setOnClickListener(new OnClickListener() {                        @Override            public void onClick(View v) {                Intent intent=new Intent("com.sxt.day07_04.MyReceiver1");                intent.putExtra("key", "hello java!");                sendBroadcast(intent);            }        });    }    //java类注册的广播接收者    private void registerReceiver() {        mReceiver=new MyReceiver2();        IntentFilter filter=new IntentFilter();//意图过滤器        filter.addAction("com.sxt.day07_04.MyReceiver2");//广播的字符串        registerReceiver(mReceiver, filter);    }    class MyReceiver2 extends BroadcastReceiver{        @Override        //收到广播执行的方法        public void onReceive(Context context, Intent intent) {            Log.i("main","MyReceiver2.onReceive():"+intent.getStringExtra("key"));        }    }        @Override    protected void onDestroy() {        super.onDestroy();        //Activity退出的时候取消广播的注册，释放资源.        unregisterReceiver(mReceiver);    }}

package com.sxt.day07_04;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.util.Log;public class MyReceiver1 extends BroadcastReceiver {    @Override    //收到广播后执行的方法    public void onReceive(Context context, Intent intent) {        Log.i("main","MyReceiver1.onReceive():"+intent.getStringExtra("key"));    }}

     
         
          
              
                   
                        
                         
                     
                
               注册全局广播接收者        
       
           广播接收者类            
                        
            广播的字符串是这个就可以接收广播