android应用开发学习笔记－BroadcastReceiver

android应用开发学习笔记－BroadcastReceiver

最近对android四大组件之一的Broadcast Receiver进行了简单学习，下面结合demo对该组件的基本用法做小结如下：

/*发送demo*/
// MainActivity.java

package com.example.rlight.broadcastsender;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {

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

Button mBtnSender = (Button)findViewById(R.id.btn_sender);
mBtnSender.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//自定义action
String actionStr = "MY_BROADCAST";
Intent intent = new Intent();
intent.setAction(actionStr);
//发送广播
sendBroadcast(intent);
}
});
}
}

/*
接收demo.接受到所注册广播后，弹toast并启动另外一个activity。
*/
// MyBroadCastReceiver.java

package com.example.rlight.broadcasttest;

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,"get msg from broadcast!",Toast.LENGTH_LONG).show();
Intent myIntent = new Intent(context,MyMainActivity.class);
myIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(myIntent);
}
}

// MyMainActivity.java

package com.example.rlight.broadcasttest;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MyMainActivity extends AppCompatActivity {

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

// AndroidManifest.xml

<receiver android:name=".MyBroadCastReceiver">
<intent-filter android:priority="50">
<action android:name="MY_BROADCAST"/>
</intent-filter>
</receiver>

注意：调用context.startActivity时需要新开一个Task，即先调用addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

在Activity中调用startActivity()时不用addFlags，原因参见Activity.java中相关实现，如下：

/**
* Launch a new activity.  You will not receive any information about when
* the activity exits.  This implementation overrides the base version,
* providing information about
* the activity performing the launch.  Because of this additional
* information, the {@link Intent#FLAG_ACTIVITY_NEW_TASK} launch flag is not
* required; if not specified, the new activity will be added to the
* task of the caller.
*
* <p>This method throws {@link android.content.ActivityNotFoundException}
* if there was no Activity found to run the given Intent.
*
* @param intent The intent to start.
* @param options Additional options for how the Activity should be started.
* See {@link android.content.Context#startActivity(Intent, Bundle)
* Context.startActivity(Intent, Bundle)} for more details.
*
* @throws android.content.ActivityNotFoundException
*
* @see {@link #startActivity(Intent)}
* @see #startActivityForResult
*/
@Override
public void startActivity(Intent intent, @Nullable Bundle options) {
if (options != null) {
startActivityForResult(intent, -1, options);
} else {
// Note we want to go through this call for compatibility with
// applications that may have overridden the method.
startActivityForResult(intent, -1);
}
}

更多细节分析可以参考链接：

http://blog.csdn.net/luoshengyang/article/details/6703247

优先级及广播劫持：

通过对优先级的设置，可以实现对sendOrderedBroadcast广播方式所发广播的劫持，实例如下：

//MyBroadcastReceiver2.java
package com.example.rlight.mybroadcastreceiver2;

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

/**
* 描述
*
* @author xxx
* @date 2016/9/18
*/
public class MyBroadcastReceiver2 extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context,"[MyBroadcastReceiver2] get msg from broadcast!",Toast.LENGTH_SHORT).show();
abortBroadcast();
}
}

// AndroidManifest.xml
<receiver android:name=".MyBroadcastReceiver2">
<intent-filter android:priority="100">
<action android:name="MY_BROADCAST">
</action>
</intent-filter>
</receiver>

更详细总结可参考：http://www.cnblogs.com/lwbqqyumidi/p/4168017.html

下面以拦截短信为例：

//  AndroidManifest.xml
<receiver android:name=".MyBroadcastReceiver2">
<intent-filter android:priority="1000">
<action android:name="MY_BROADCAST">
</action>
</intent-filter>
<intent-filter android:priority="1000">
<action android:name="android.provider.Telephony.SMS_RECEIVED">
</action>
</intent-filter>
</receiver>
</application>
<uses-permission android:name="android.permission.SEND_SMS"></uses-permission>
<uses-permission android:name="android.permission.RECEIVE_SMS"></uses-permission>
<uses-permission android:name="android.permission.READ_SMS"></uses-permission>

在4.4及后续版本不支持通过abortBroadcast实现短信拦截：http://blog.csdn.net/l173864930/article/details/17019615