一、使用本地廣播

1.本地廣播一個(gè)舉例

package com.example.broadcasttest2;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.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class MainActivity extends Activity { private IntentFilter intentFilter; private LocalReceiver localReceiver; private LocalBroadcastManager localBroadcastManager; private NetworkChangeReceiver networkChangeReceiver; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); intentFilter = new IntentFilter(); intentFilter.addAction('android.net.conn.CONNECTIVITY_CHANGE'); networkChangeReceiver = new NetworkChangeReceiver(); registerReceiver(networkChangeReceiver,intentFilter); localBroadcastManager = LocalBroadcastManager.getInstance(this);//獲取實(shí)例 Button button = (Button) findViewById(R.id.button); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { //下面這行代碼是用來全局廣播的// Intent intent = new Intent('com.example.broadcasttest.MY_BROADCAST'); //下面這行代碼是用來本地廣播的（也就是app內(nèi)部傳遞廣播） Intent intent = new Intent('com.example.broadcasttest.LOCAL_BROADCAST'); localBroadcastManager.sendBroadcast(intent);//發(fā)送本地廣播 // sendBroadcast(intent); //我們關(guān)閉上面一行代碼，然后寫另一種方法sendOrderedBroadcast,發(fā)送有序廣播 sendOrderedBroadcast(intent,null); } }); intentFilter = new IntentFilter(); intentFilter.addAction('com.example.broadcasttest.LOCAL_BROACAST'); localReceiver = new LocalReceiver(); localBroadcastManager.registerReceiver(localReceiver,intentFilter);//注冊本地廣播監(jiān)聽器 } @Override protected void onDestroy() { super.onDestroy();// unregisterReceiver(networkChangeReceiver); localBroadcastManager.unregisterRecerver(localReceiver); } class NetworkChangeReceiver extends BroadcastReceiver{ @Override public void onReceive(Context context,Intent intent) { ConnectivityManager connectionMananger = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo networkInfo = connectionMananger.getActiveNetworkInfo(); if(networkInfo != null && networkInfo.isAvailable()) { Toast.makeText(context, 'network is available', Toast.LENGTH_SHORT).show(); } else { Toast.makeText(context, 'network is unavailable', Toast.LENGTH_SHORT).show(); } } } class LocalReceiver extends BroadcastReceiver { @Override public void onReceive(Context context,Intent intent) { Toast.makeText(context,'received local broadcast',Toast.LENGTH_SHORT).show(); } }}

通過LocalBroadcastManager的getInstance()方法來獲取一個(gè)實(shí)例，注冊廣播是用的registerReceiver()方法，傳入的參數(shù)一個(gè)是localReceiver的內(nèi)部實(shí)例，一個(gè)是IntentFilter實(shí)例。最后在onCreate方法中調(diào)用發(fā)送廣播的方法。最后我們在按鈕的點(diǎn)擊事件里面發(fā)送一條com.example.broadcasttest.LOCAL_BROADCAST廣播，然后在LocalReceiver里面去接收這條廣播。

注意點(diǎn)：本地廣播是無法通過靜態(tài)注冊的方式來接收的，其實(shí)這也完全可以理解，因?yàn)殪o態(tài)注冊主要就是為了讓程序在未啟動的時(shí)候也能收到廣播，而發(fā)送本地廣播的時(shí)候，我們的程序就已經(jīng)啟動了，因?yàn)橐餐耆恍枰褂渺o態(tài)注冊的功能。

2.使用本地廣播的優(yōu)勢

（1）程序內(nèi)部傳遞，防止機(jī)密數(shù)據(jù)泄露；（2）其他程序無法將廣播發(fā)送到我們的程序內(nèi)部，防止安全漏洞的隱患;（3）發(fā)送本地廣播更加高效。

二、實(shí)現(xiàn)強(qiáng)制下線功能

1.實(shí)現(xiàn)強(qiáng)制下線的邏輯

無論在我們在程序的哪個(gè)活動界面，一旦收到強(qiáng)制下線的廣播，就跳出來一個(gè)界面，必須點(diǎn)擊“確認(rèn)“，然后直接跳轉(zhuǎn)到登錄界面。

2.首先創(chuàng)建一個(gè)類用于管理所有的活動

package com.example.broadcastbestpractice;import java.util.ArrayList;import java.util.List;import android.app.Activity;public class ActivityCollector { public static List<Activity> activities = new ArrayList<Activity>(); 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(); } } }}

3.創(chuàng)建一個(gè)基類BaseActivity作為所有活動的父類

package com.example.broadcastbestpractice;import android.app.Activity;import android.os.Bundle;public class BastActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); ActivityCollector.addActivity(this); } @Override public void onDestroy() { super.onDestroy(); ActivityCollector.removeActivity(this); }}

4.接著需要建立一個(gè)登錄頁面的布局

<?xml version='1.0' encoding='utf-8'?><!-- android:shrinkColumns設(shè)置允許被收縮的列序號 android:strectColumns設(shè)置允許被拉伸的列序號 --><TableLLayout xmlns:android='http://schemas.android.com/apk/res/android' android:layout_width='match_parent' android:layout_height='match_parent' android:strectColumns = '1' > <TableRow> <TextView android:layout_height = 'wrap_content' android:text='Account:' /> <EditText android: android:layout_height='wrap_content' android:hint='Input your account' /> </TableRow> <TableRow> <TextView android:layout_height='wrap_content' android:text='Password:' /> <EditTest android: android:layout_height='wrap_content' android:inputType='textPassword' /> </TableRow> <TableRow> <Button android: android:layout_height='wrap_content' android:layout_span='2' android:text='Login' /> </TableRow></TableLayout>

后面的我們下次連載接著寫。

三、源碼：

BroadcastTest2BroadcastBestPracticehttps://github.com/ruigege66/Android/tree/master/BroadcastTest2https://github.com/ruigege66/Android/tree/master/BroadcastBestPractice

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