Android四大组件之 BroadCastReceive 使用总结

BroadCast的定义:

广播是一种订阅--通知 事件,广播接收者向Android系统 register (订阅广播),广播发送者向Adnroid系统 sendBroadCast(发送广播),然后Android 系统通知所有注册该广播的接收者,广播接收者收到自己注册的广播之后实现自己想做的事情(该事情一般不超过10s,否则应用会出现ANR)。

BroadCast的分类:

1.无序广播:也就是普通广播,只要注册了该action的广播接收者都能收到该广播,且没有先后顺序。
2.有序广播:广播接收者按照优先级高低依次接受该广播,并且优先接收的广播可以通过setResultExtras(Bundle)方法,将处理好的结果传送到下一个广播接收者那里。
3.粘性广播:发送广播调用的方法 sendStickyBroadcast(Intent),和sendBroadcast(Intent)不同。
粘性广播会一直保留在内存当中,直到有广播接收者注册该广播,该广播才算结束。不好解释,等会具体看例子

BroadCase的使用:

一.普通广播:根据注册方式不同可以分为 静态注册广播和动态注册广播。

1.静态注册广播使用实例

AndroidManifest.xml 如下:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.xjp.mybroadcast">

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <!--静态注册广播,此处需要添加广播的action-->
        <receiver android:name=".BroadCastReceive1">
            <intent-filter>
                <action android:name="com.xjp.mybroadcast.BroadCastReceive1"></action>
            </intent-filter>
        </receiver>
    </application>

</manifest>

2.广播接收者实现如下:

package com.xjp.mybroadcast;

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

/**
 * Description:静态广播接收器
 * User: xjp
 * Date: 2015/5/14
 * Time: 14:56
 */

public class BroadCastReceive1 extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        //TODO 接收到广播之后处理自己的事情
        String action = intent.getAction();
        String result = intent.getStringExtra("key");
        MyLog.d("the BroadCast action is " + action + "   the BroadCast receive result is " + result);
    }
}

3.广播发送者实现如下:

package com.xjp.mybroadcast;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;


public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    private Button btnSend;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnSend = (Button) findViewById(R.id.button);
        btnSend.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                sendBraodCast();
                break;
        }
    }

    private void sendBraodCast() {

        /**
         * 申明静态广播的 action 行为
         */
        String action = "com.xjp.mybroadcast.BroadCastReceive1";
        Intent intent = new Intent(action);
        intent.putExtra("key", "静态广播测试");
        sendBroadcast(intent);
    }
}

打印结果如下:
技术分享

4.静态注册广播特点:

1.注册广播在 AndroidManifest.xml中。
2.广播接收者需重新 继承 BroadcastReceiver 类来实现 onReceive()抽象方法。
3.应用退出无需 注销广播,因此导致:即使广播退出之后,如果有其他应用发送该action行为的广播,此应用还是能接收到该广播的,也就是还会打印上面的 结果。

二.动态广播:

示例

<pre name="code" class="java">package com.xjp.mybroadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v4.content.LocalBroadcastManager;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;


public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    private Button btnSend;

    private BroadCastReceive2 myReceive;

    private IntentFilter filter;

    private final static String ACTION = "com.xjp.mybroadcast.BroadCastReceive2";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnSend = (Button) findViewById(R.id.button);
        btnSend.setOnClickListener(this);

        myReceive = new BroadCastReceive2();
        filter = new IntentFilter();
        filter.addAction(ACTION);

    }


    @Override
    protected void onResume() {
        /**
         * 注册广播
         */

        LocalBroadcastManager.getInstance(this).registerReceiver(myReceive, filter);//官方建议使用

//        this.registerReceiver(myReceive, filter);

        super.onResume();
    }


    @Override
    protected void onPause() {
        /**
         * 注销广播
         */

        LocalBroadcastManager.getInstance(this).unregisterReceiver(myReceive);//官方建议使用

//        this.unregisterReceiver(myReceive);

        super.onPause();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                sendBraodCast();
                break;
        }
    }

    private void sendBraodCast() {

        /**
         * 申明广播的 action 行为
         */
        Intent intent = new Intent(ACTION);
        intent.putExtra("key", "动态广播测试");

        /**
         * 官方提倡使用如下发送广播,原因是更快,更安全,不会导致内存泄漏
         */
        LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

//        this.sendBroadcast(intent);
    }


    /**
     * 内部类实现广播接收器
     */
    private class BroadCastReceive2 extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            //TODO 接收到广播之后处理自己的事情
            String action = intent.getAction();
            String result = intent.getStringExtra("key");
            MyLog.d("the BroadCast action is " + action + "   the BroadCast receive result is " + result);
        }
    }
}


打印结果如下:
技术分享

动态广播特点:

1.在代码中调用registerReceiver()方法 注册广播。
2.广播接收者需重新 继承 BroadcastReceiver 类实现内部类。
3.动态广播在应用退出时需要 调用unregisterReceiver()方法来注销广播。如果应用退出时没有注销广播,会报如下错误:
技术分享
因此,我们通常的做法是:在 onResume()中注册广播,在onPause中注销广播。
4.当广播注销之后就接收不到任何系统发送的广播了。

三.有序广播:

示例:

<pre name="code" class="java">package com.xjp.mybroadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;


public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    private Button btnSend;

    private BroadCastReceive2 myReceive;

    private BroadCastReceive3 myReceive3;

    private IntentFilter filter;

    private IntentFilter filter3;

    private final static String ACTION = "com.xjp.mybroadcast.BroadCastReceive2";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnSend = (Button) findViewById(R.id.button);
        btnSend.setOnClickListener(this);

        myReceive = new BroadCastReceive2();
        filter = new IntentFilter();
        filter.addAction(ACTION);
        filter.setPriority(2);//设置广播的优先级, -1000~1000 ,数字越大,优先级越高。

        myReceive3 = new BroadCastReceive3();
        filter3 = new IntentFilter();
        filter3.addAction(ACTION);
        filter3.setPriority(1);


    }


    @Override
    protected void onResume() {
        /**
         * 注册广播
         */
        registerReceiver(myReceive, filter);
        registerReceiver(myReceive3, filter3);


        super.onResume();
    }


    @Override
    protected void onPause() {
        /**
         * 注销广播
         */

        unregisterReceiver(myReceive);
        unregisterReceiver(myReceive3);

        super.onPause();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                sendBraodCast();
                break;
        }
    }

    private void sendBraodCast() {

        /**
         * 申明广播的 action 行为
         */
        Intent intent = new Intent(ACTION);
        intent.putExtra("key", "有序广播测试");

        this.sendOrderedBroadcast(intent, null);
    }


    /**
     * 内部类实现广播接收器
     */
    private class BroadCastReceive2 extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            //TODO 接收到广播之后处理自己的事情
            String action = intent.getAction();
            String result = intent.getStringExtra("key");
            MyLog.d("the BroadCast action is " + action + "   the BroadCast receive result is " + result);

            Bundle bundle = new Bundle();
            bundle.putString("key", "有序广播处理之后" + "\n" + "再次发送给下一个广播接收者");
            intent.putExtra("bundle", bundle);
            setResultExtras(bundle);
            //切断广播,不再让此广播继续往下发送。
            //  abortBroadcast();
        }
    }

    /**
     * 内部类实现广播接收器
     */
    private class BroadCastReceive3 extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            //TODO 接收到广播之后处理自己的事情
            String action = intent.getAction();
            //要不要接受上一个广播接收器receiver2传来的的数据
            Bundle bundle = getResultExtras(true);
            MyLog.d("the BroadCast action is " + action + "   the BroadCast receive result is " + bundle.getString("key"));
        }
    }
}


有序广播特点:

1.所有广播接收者的action是一致的,发送有序广播调用 sendOrderedBroadcast()方法。
2.有序广播的接收者需要调用setPriority()方法设置广播接收者的优先级。数字越大,优先接受广播。
3.有序广播如果需要终止 广播继续往下发送,可以调用 abortBroadcast()方法切断广播。
4.先接收广播者可以将自己的处理结果通过setResultExtras()方法继续传递给下一个广播接收者。
5.后接收者可以调用 getResultExtras(true)来自己决定是否接收上一个广播传递过来的数据。

四.粘性广播:

示例  需要在 AndroidManifest.xml中添加 权限
<uses-permission android:name="android.permission.BROADCAST_STICKY"></uses-permission>

发送广播的Activity
package com.xjp.mybroadcast;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.widget.Button;


/**
 * 发送广播的Activity
 */
public class MainActivity extends ActionBarActivity implements View.OnClickListener {

    private Button btnSend;


    private final static String ACTION = "com.xjp.mybroadcast.BroadCastReceive1";
    private final static String ACTION1 = "com.xjp.mybroadcast.BroadCastReceive2";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btnSend = (Button) findViewById(R.id.button);
        btnSend.setOnClickListener(this);
    }


    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                sendBraodCast();
                break;
        }
    }

    private void sendBraodCast() {

        /**
         * 申明广播的 action 行为
         */
        Intent intent = new Intent(ACTION);
        intent.putExtra("key", "普通广播测试");
        sendBroadcast(intent);

        Intent intent1 = new Intent(ACTION1);
        intent1.putExtra("key", "粘性广播测试");
        sendStickyBroadcast(intent1);
        startActivity(new Intent(this, RecevieActivity.class));
    }
}
接受广播的Activity
package com.xjp.mybroadcast;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;

/**
 * Description:接受广播的Activity
 * User: xjp
 * Date: 2015/5/14
 * Time: 17:03
 */

public class RecevieActivity extends Activity {

    private final static String ACTION1 = "com.xjp.mybroadcast.BroadCastReceive1";
    private final static String ACTION2 = "com.xjp.mybroadcast.BroadCastReceive2";

    private Receive receive;

    private IntentFilter filter1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        receive = new Receive();

        filter1 = new IntentFilter();
        filter1.addAction(ACTION1);
        filter1.addAction(ACTION2);

    }

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(receive, filter1);
    }

    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(receive);
    }

    private class Receive extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            String result = intent.getStringExtra("key");
            MyLog.d("the BroadCast action is " + action + "   the BroadCast receive result is " + result);
        }
    }
}

打印结果如下:
技术分享
从结果来看,只有粘性广播才能接收到广播信息。

粘性广播特点:

1.需要在AndroidManifest.xml中添加权限
<uses-permission android:name="android.permission.BROADCAST_STICKY"></uses-permission>
2.粘性广播发送除了调用方法不同sendStickyBroadcast(intent1),其他都一样。
3.一般广播都是先注册广播,才能接收到广播,而粘性广播可以做到先发送广播,哪里需要接收该广播就哪里注册,可以后注册广播拿到广播的结果。这就是 普通广播和粘性广播的区别。从示例中也看出了普通广播在跳转到ReceiveActivity中是接受不到广播发送者发出的广播的,只有粘性广播才能接收到。

有人会奇怪,平时也没看到哪里使用粘性广播??其实我也是看到Android 系统中 监测电池电量部分发现的。贴上代码如下:

// Register for the battery changed event
IntentFilter filter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);

/ Intent is sticky so using null as receiver works fine
// return value contains the status
Intent batteryStatus = this.registerReceiver(null, filter);

// Are we charging / charged?
int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING
  || status == BatteryManager.BATTERY_STATUS_FULL;

boolean isFull = status == BatteryManager.BATTERY_STATUS_FULL;

// How are we charging?
int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC; 

广播的生命周期:

当广播接收者接收到广播调用完onReceive()方法之后,广播的生命周期就结束了。

因此广播接收器不能执行超过10s耗时任务,也不能在onReceive()方法中创建Thread 来执行耗时任务,你可以开启一个Service来执行后台耗时任务,具体可以参考Android 四大组件之Service 的生命周期和使用




广播的大概原理:

广播是怎么发送的?又是怎么接收的?

我们知道,只有先注册了某个广播之后,广播接收者才能收到该广播。广播注册的一个行为是将自己感兴趣的IntentFilter注册到Android系统的AMS(ActivityManagerService)中,里面保存了一个IntentFilter列表。广播发送者将自己的IntentFilter 的action行为发送到AMS中,然后遍历AMS中的IntentFilter列表,看谁订阅了该广播,然后将消息遍历发送到注册了相应IntentFilter的Activity或者Service中-----也就是会调用抽象方法onReceive()方法。其中AMS起到了中间桥梁作用。

系统广播:

Android系统中有很多系统广播,比如:
Event Description
Intent.ACTION_BOOT_COMPLETED Boot completed. Requires the android.permission.RECEIVE_BOOT_COMPLETEDpermission.
Intent.ACTION_POWER_CONNECTED Power got connected to the device.
Intent.ACTION_POWER_DISCONNECTED Power got disconnected to the device.
Intent.ACTION_BATTERY_LOW Triggered on low battery. Typically used to reduce activities in your app which consume power.
Intent.ACTION_BATTERY_OKAY Battery status good again.
系统广播具体怎么用?网络上一搜一大把,这里就不讲了。和我们写的广播使用都差不多。


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