Alexkn Android first line of code-7. Broadcast

The broadcast in 0.Android can be divided into two types, standard broadcast and ordered broadcast. Standard broadcast (normal broadcasts) is a fully asynchronous broadcast that, after broadcast, almost all broadcast receivers receive this broadcast message at the same time,

An ordered broadcast (Ordered broadcasts) is a synchronous broadcast that, after a broadcast, only one broadcast receiver can receive this broadcast message at the same time.

1. Monitoring System Broadcast (power/wifi/time zone change ... ）

If you need to listen to a system broadcast, you need two steps:

(1) Rewrite the broadcastreceiver in the OnReceive method can be, to achieve their own receiver;

     Public class extends broadcastreceiver {        @Override        publicvoid  onreceive (context context, Intent Intent) {            Toast.maketext (context,"Network Change", Toast.length_short). Show ();        }    }

(2) Define an intent filter to filter out the broadcast

    protected void onCreate (Bundle savedinstancestate) {        super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main);         New Intentfilter ();        Intentfilter.addaction ("Android.net.conn.CONNECTIVITY_CHANGE");         New networkchangereceiver ();        Registerreceiver (Networkchangereceiver,intentfilter);    }

(3) Register in Androidmainifest.xml

<? XML version= "1.0" encoding= "Utf-8" ?> <  xmlns:android= "http://schemas.android.com/apk/res/android"    package  = "Com.alex.learn.broadcasttest">    <android:name = "Android.permission.ACCESS_NETWORK_STATE" />

2. send a regular broadcast

(1) Implement a broadcast receiver Mybroadcastreceiver, define what to do when you receive a broadcast

 Public class extends broadcastreceiver {    @Override    publicvoid  onreceive (context context, Intent Intent) {        "received in Mybroadcastreceiver", Toast.length_short). Show ();    }}

(2) Implement a broadcast transmitter that defines the transmission of the broadcast

 Public classMainactivityextendsappcompatactivity {PrivateIntentfilter Intentfilter; PrivateNetworkchangereceiver Networkchangereceiver; @Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);        Setcontentview (R.layout.activity_main); Button Button=(Button) Findviewbyid (R.id.button); Button.setonclicklistener (NewView.onclicklistener () {@Override Public voidOnClick (View v) {Intent Intent=NewIntent ("Com.example.broadcasttest.MY_BROADCAST");            Sendbroadcast (Intent);    }        }); }

Now that the Com.example.broadcasttest.MY_BROADCAST is bound to the intent, it is necessary to register a receiver in the Androidmainifest.xml

<manifest xmlns:android= "Http://schemas.android.com/apk/res/android" Package= "Com.alex.learn.broadcasttest" > <uses-permission android:name= "Android.permission.ACCESS_NETWORK_STATE"/ > <uses-permission android:name= "Android.permission.RECEIVE_BOOT_COMPLETED"/> <Application Android:allowbackup= "true"Android:icon= "@mipmap/ic_launcher"Android:label= "@string/app_name"Android:supportsrtl= "true"Android:theme= "@style/apptheme" >        ...        <receiver android:name= ". Mybroadcastreceiver "> <intent-filter> <action android:name=" com.example.broadcasttes T.my_broadcast "/> </intent-filter> </receiver></application>

Alexkn Android first line of code-7. Broadcast