Broadcast广播机制

简介

android中的广播有两种类型为：标准广播和有序广播。
1. 标准广播为完全异步的广播，在广播发出后所有的广播接收器都能接收到此条广播，也意味着标准广播不能被截断。
2. 有序广播是有先后顺序的按照优先级的高低来传递广播，意味着可以被截断。

动态注册

package com.test.brodcast;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.net.ConnectivityManager;import android.net.NetworkInfo;import android.os.Bundle;import android.widget.Toast;public class MainActivity extends Activity {    //设置意图传播器    private IntentFilter intentFilter;    //定义为全局变量方便调用，NetworkChangeReceiver为内部类    private NetworkChangeReceiver networkChangeReceiver;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //初始化IntentFilter        intentFilter =new IntentFilter();        //添加新的活动，android.net.conn.CONNECTIVITY_CHANGE这些活动都是android内部定义的活动，可查看api        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");        //得到自己继承于BroadcastReceiver的类的对象        networkChangeReceiver = new NetworkChangeReceiver();        //注册广播接收机，传入继承过BroadcastReceiver的类的对象，以及要监听的活动        registerReceiver(networkChangeReceiver, intentFilter);    }    @Override    protected void onDestroy() {        // 活动销毁时记得取消注册        super.onDestroy();        unregisterReceiver(networkChangeReceiver);    }    /**     *自己定义的广播类，必须继承BroadcastReceiver     */    class NetworkChangeReceiver extends BroadcastReceiver{        @Override        public void onReceive(Context context, Intent intent) {            //连接管理类            ConnectivityManager connectionManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);            //获得网络连接的信息            NetworkInfo networkInfo = connectionManager.getActiveNetworkInfo();            //判断网络连接的状态            if(networkInfo != null&& networkInfo.isAvailable()){                Toast.makeText(context, "network is available", Toast.LENGTH_SHORT).show();            }else{                Toast.makeText(context, "network is unaviailable", Toast.LENGTH_SHORT).show();        }        }    }}

在AndroidMainfest.xml中增加权限(四大组件的毛病)没有用到receiver权限,用到的为网络状态的权限

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

静态注册实现开机启动

继承BroadcastReceiver,不要再onReceive（）添加过多的逻辑或者进行任何耗时的操作，因为在广播接收器中是不允许开启线程的

public class BootCompleteReceiver extends BroadcastReceiver{    @override    public void onReceive(Context context,Intent intent){        Toast.makeText(context,"Boot Complete",Toast.LENGTH).show();    }}

在AndroidMainfest.xml中增加权限

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>在application下添加<receiver android:name=".BootCompleteReceiver">    <intent-filter>        <action android:name="android.intent.action.BOOT_COMPLETED"/>    </intent-filter></receiver>

发送自定义广播

创建继承类（*）

package com.example.standardbroadcast;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.widget.Toast;public class MyBroadcastReceiver extends BroadcastReceiver{    @Override    public void onReceive(Context context, Intent intent) {        Toast.makeText(context, "receives in MyBroadcastReceiver", Toast.LENGTH_SHORT).show();;    }}

布局，仅放有一个按钮，完全为了测试用

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.example.standardbroadcast.MainActivity" >    <Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world" /></RelativeLayout>

主类（**）

package com.example.standardbroadcast;import android.support.v7.app.ActionBarActivity;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button=(Button) findViewById(R.id.button);        button.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                //为对应关系，可以随便取名，但是一般定义为com.example.standardbroadcast.MY_BROADCAST                //包名加后缀的形式方便识别,创建一个intent                "当然你可以在intent中携带数据进行传输"                Intent intent = new Intent("com");                //将广播发送出去                sendBroadcast(intent);            }        });    }

在AndroidMainfest.xml中增加权限（#）

注意添加到application 的分坐标上

      <receiver android:name=".MyBroadcastReceiver">            <intent-filter>            <!--监听发出"com"的事件，只要有就会相应，前提是没有流产-->                <action android:name="com"/>            </intent-filter>        </receiver>    </application>

使用本地广播(和动态广播有异曲同工之妙)，这样发出的广播只能在应用程序的内部使用，使用时不用再配置文件中注册。

package com.example.standardbroadcast;import android.support.v4.content.LocalBroadcastManager;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.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class MainActivity extends Activity {    //内容传播者    private IntentFilter mIntentFilter;    //建立自己创建类的对象    private LocalReceiver mLocalReceiver;    //为系统内部类，本地广播管理器    private LocalBroadcastManager mLocalManger;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button=(Button) findViewById(R.id.button);        //得到本地广播管理的实例        mLocalManger =LocalBroadcastManager.getInstance(this);         button.setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                //为对应关系，可以随便取名，但是一般定义为com.example.standardbroadcast.MY_BROADCAST                //包名加后缀的形式方便识别                "建立内部的广播传递信息的标志"                Intent intent = new Intent("comaction");                //自己创建的类去发送广播                mLocalManger.sendBroadcast(intent);            }        });        //初始化内容传播者        mIntentFilter = new IntentFilter();        //添加要接受的活动        mIntentFilter.addAction("comaction");        //创建自己所建类的实例        mLocalReceiver = new LocalReceiver();        //用本地广播去注册        mLocalManger.registerReceiver(mLocalReceiver, mIntentFilter);    }    class LocalReceiver extends BroadcastReceiver{        @Override        public void onReceive(Context context, Intent intent) {            Toast.makeText(context, "receive in localBroadcast", Toast.LENGTH_SHORT).show();        }    }}

实现

本地广播的优点

1. 可以明确的知道正在发送的广播不会离开我们的程序，因此不用担心机密数据的泄露。

2. 其他的程序无法将广播发送到我们的程序内部，不用担心有安全漏洞。

3.发送本地广播比起发送系统全局广播会更加高效。

有序广播

在（*）加入abortBroadcast()，将广播流产

abortBroadcast();

将原来（**）中的sendBroadcast(intent)改为

//为对应关系，可以随便取名，但是一般定义为com.example.standardbroadcast.MY_BROADCAST        //包名加后缀的形式方便识别        Intent intent = new Intent("com");        sendOrderedBroadcast(intent, null);

将原来的（#）的权限添加

   <intent-filter android:priority="100">

活动管理类

import java.util.ArrayList;import java.util.List;import android.app.Activity;public class ActivityCollector {    public static List<Activity> activities = new ArrayList<>();    public static void addActivity(Activity activity){        activities.add(activity);    }    public static void removeActivity(Activity activity){        activities.remove(activity);    }    public static void finishAll(){        for (Activity activity:activities){            if(!activity.isFinishing()){                activity.finish();            }        }    }}

然后创建BaseActivity作为所有活动的父类

import android.app.Activity;import android.os.Bundle;public class BaseActivity extends Activity{    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ActivityCollector.addActivity(this);    }    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        ActivityCollector.removeActivity(this);    }}

用途

闹钟用到AlarmManager和PendingIntent

主程序

package com.test.teacherbroadcaststembereight;import android.support.v7.app.ActionBarActivity;import android.app.Activity;import android.app.AlarmManager;import android.app.PendingIntent;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity implements OnClickListener{    private Button button;    private Button mButtonCancel;    private Button mButtonAlarm;    private MyBroadcast broadcast;    private AlarmManager mAlarmManager;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);         broadcast=new MyBroadcast();         IntentFilter filter=new IntentFilter();         filter.addAction("com.test.mytest");         registerReceiver(broadcast, filter);         mButtonAlarm=(Button) findViewById(R.id.alarm_button);         mButtonAlarm.setOnClickListener(this);         mButtonCancel=(Button) findViewById(R.id.alarm_cancle);         mButtonCancel.setOnClickListener(this);        button= (Button) findViewById(R.id.button1);        button.setOnClickListener(this);        mAlarmManager=(AlarmManager) getSystemService(Context.ALARM_SERVICE);    }    @Override    public void onClick(View v) {        switch(v.getId()){        case R.id.button1:            Intent intent=new Intent();            intent.setAction("com.test.mytest");            sendBroadcast(intent);            break;        case R.id.alarm_button:            Intent intent1=new Intent();            intent1.setAction("com.test.mytest");            PendingIntent pendingIntent=PendingIntent.getBroadcast(MainActivity.this, 2, intent1, PendingIntent.FLAG_UPDATE_CURRENT);            mAlarmManager.setRepeating(AlarmManager.RTC_WAKEUP,System.currentTimeMillis()+5000,3000,pendingIntent);            break;        case R.id.alarm_cancle:            Intent intent2=new Intent();            intent2.setAction("com.test.mytest");            PendingIntent pendingIntent2=PendingIntent.getBroadcast(MainActivity.this, 2, intent2, PendingIntent.FLAG_UPDATE_CURRENT);            pendingIntent2.cancel();            break;        }    }    @Override    protected void onDestroy() {        // TODO Auto-generated method stub        super.onDestroy();        unregisterReceiver(broadcast);    }}

广播程序

package com.test.teacherbroadcaststembereight;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.widget.Toast;public class MyBroadcast extends BroadcastReceiver{    @Override    public void onReceive(Context context, Intent intent) {        Toast.makeText(context, "guangbo", Toast.LENGTH_SHORT).show();    }}

主布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <Button         android:id="@+id/button1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="发送广播"/>    <Button         android:id="@+id/alarm_button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="闹钟"/>    <Button         android:id="@+id/alarm_cancle"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="cancle"/></LinearLayout>

系统自带广播查看api（Intent)