(eight) Android broadcast receiver Broadcastreceiver

First, use broadcast Reciver 1. Right-click the Java folder and New->other->broadcast receiver will generate a receiver entry in the Androidmanifest.xml file

<?xml version= "1.0" encoding= "Utf-8"?>
<manifest xmlns:android= "Http://schemas.android.com/apk/res/android"
Package= "Com.example.shiyanshi.learnbroadcast" >

<application
Android:allowbackup= "true"
android:icon= "@mipmap/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>

<receiver
Android:name= ". Myreceiver "
Android:enabled= "true"
Android:exported= "true" >
</receiver>
</application>

</manifest>

2. Also generates a Myreceiver class in which onreceive is used to respond to messages sent by the Sendbroadcast function

Package com.example.shiyanshi.learnbroadcast;

Import Android.content.BroadcastReceiver;
Import Android.content.Context;
Import android.content.Intent;

public class Myreceiver extends Broadcastreceiver {
    Public Myreceiver () {
    }

    @Override
    public void OnReceive (context context, Intent Intent) {
        Todo:this method is called if the Broadcastreceiver is receiving
        An Intent broadcast.
        throw new Unsupportedoperationexception ("not yet implemented");
        System.out.println ("RECV Data:" +intent.getstringextra ("Data"));
    }
}

3. Call the Sendbroadcast function to send the message, the function requires a intent

Package com.example.shiyanshi.learnbroadcast;

Import android.app.Activity;
Import android.content.Intent;
Import Android.os.Bundle;
Import Android.view.Menu;
Import Android.view.MenuItem;
Import Android.view.View;


public class Mainactivity extends Activity implements View.onclicklistener {

@Override
protected void OnCreate (Bundle savedinstancestate) {
Super.oncreate (savedinstancestate);
Setcontentview (R.layout.activity_main);

Findviewbyid (r.id.btnsendmsg). Setonclicklistener (this);
}

@Override
public boolean Oncreateoptionsmenu (Menu menu) {
Inflate the menu; This adds items to the action bar if it is present.
Getmenuinflater (). Inflate (R.menu.menu_main, menu);
return true;
}

@Override
public boolean onoptionsitemselected (MenuItem item) {
Handle Action Bar Item clicks here. The Action Bar would
Automatically handle clicks on the Home/up button, so long
As you specify a the parent activity in Androidmanifest.xml.
int id = item.getitemid ();

Noinspection simplifiableifstatement
if (id = = r.id.action_settings) {
return true;
}

return super.onoptionsitemselected (item);
}

@Override
public void OnClick (view view) {
Switch (View.getid ()) {
Case R.ID.BTNSENDMSG:
Intent Intent =new Intent (this,myreceiver.class);
Intent.putextra ("Data", "Henry");
Sendbroadcast (Intent);
Break
}
}
}

Ii. Dynamic registration and deregistration 1. When you delete receiver from the Androidmanifest.xml file, you need to register and log off dynamically to send and receive messages <receiver
Android:name= ". Myreceiver "
Android:enabled= "true"
Android:exported= "true" >
</receiver>
The 2.MainActivity changes are as follows: When sending a message message, intent to use the implicit intent (myreceiver.action as a constant string defined public static final string action= " Com.example.shiyanshi.learnbroadcast.intent.action.MyReceiver ";//The first half of the package name, the latter part when the intent format, Myreceiver is the class used in response to sendbroadcast above), when registering with the Registerreceiver function, the Unregisterreceiver function function prototype is used when logging out: public Intent Registerreceiver (broadcastreceiver receiver, intentfilter filter) public void Unregisterreceiver (broadcastreceiver Receiver receiver is the Myreceiver class that we claim to be used to respond to sendbroadcast when we create a new broadcast, and filter is the filters that need to be remembered for passing implicit intent-like parameters.

public class Mainactivity extends Activity implements View.onclicklistener {

Private Myreceiver Receiver=null;

@Override
protected void OnCreate (Bundle savedinstancestate) {
Super.oncreate (savedinstancestate);
Setcontentview (R.layout.activity_main);

Findviewbyid (r.id.btnsendmsg). Setonclicklistener (this);
Findviewbyid (R.id.btnregister). Setonclicklistener (this);
Findviewbyid (R.id.btnunregister). Setonclicklistener (this);
}

@Override
public boolean Oncreateoptionsmenu (Menu menu) {
Inflate the menu; This adds items to the action bar if it is present.
Getmenuinflater (). Inflate (R.menu.menu_main, menu);
return true;
}

@Override
public boolean onoptionsitemselected (MenuItem item) {
Handle Action Bar Item clicks here. The Action Bar would
Automatically handle clicks on the Home/up button, so long
As you specify a the parent activity in Androidmanifest.xml.
int id = item.getitemid ();

Noinspection simplifiableifstatement
if (id = = r.id.action_settings) {
return true;
}

return super.onoptionsitemselected (item);
}

@Override
public void OnClick (view view) {
Switch (View.getid ()) {
Case R.ID.BTNSENDMSG:
Intent Intent =new Intent (this,myreceiver.class);
Use implicit intent for dynamic registration and logoff, but not for display intent
Intent intent=new Intent (myreceiver.action);
Intent.putextra ("Data", "Henry");
Sendbroadcast (Intent);
Break
Case R.id.btnregister:
if (receiver==null) {
Receiver=new Myreceiver ();
Registerreceiver (receiver,new intentfilter (myreceiver.action));
}
Break
Case R.id.btnunregister:
if (receiver!=null) {
Unregisterreceiver (receiver);
Receiver=null;
}
Break
}
}
}

Broadcast priority when sending data, in the form of an implicit intent (e.g. above), the action name in two receivers simultaneously, both can receive the data simultaneously. By default, the receiver that is written last has a high priority, and the higher the value, the higher the priority, and the more the first response to the data that can be displayed in the Intent-filter under receiver.

<receiver
        Android:name= ". MyReceiver1 "
        Android:enabled= "true"
        Android:exported= "true" >
        <intent-filter android:priority= "2" >
            <action android:name= "Com.example.shiyanshi.learnbroadcast.intent.action.MyReceiver"/>
        </intent-filter>
    </receiver>
    <receiver android:name= ". Myreceiver "
        Android:enabled= "true"
        Android:exported= "true" >
        <intent-filter android:priority= "1" >
            <action android:name= "Com.example.shiyanshi.learnbroadcast.intent.action.MyReceiver"/>
        </intent-filter>
    </receiver>
</application>

In addition, when the high-priority onreceive executes, you can invoke Abortbroadcast in it to terminate the delivery of the data. OnReceive with low priority will not execute. NOTE: If you want to use the Abortbroadcast function, you will need to use sendorderedbroadcast instead of sendbroadcast when sending it, otherwise you'll get a pop-up error java.lang.RuntimeException : Broadcastreceiver trying to return result during a non-ordered broadcast.

Intent intent=new Intent (myreceiver.action);
                Intent.putextra ("Data", "Henry");
                Sendbroadcast (Intent);
                Sendorderedbroadcast (Intent,null);

Where the second parameter of Sendorderedbroadcast is used to indicate a permission, which can be null

(eight) Android broadcast receiver Broadcastreceiver