Android四大组件之- BroadcastReceiver的创建与应用
文章目录
- 前言
- 一、广播接收器的两种注册方法
-
- 动态注册
- 静态注册
- 二、发送广播的应用
-
- sendBroadcast发送本地标准广播，app内自发自收
- localBroadcastManager.sendBroadcast发送本地标准广播，app内自发自收
- 发送本地有序广播
- 接收三方应用发送的广播
- 三、其他应用
-
- 通过广播打开activity和AlertDialog
- 总结
前言
我学习东西都是先学怎么做，再学为什么这么做，所以我的学习笔记也是代码居多，直接复制代码运行，通过观察代码的运行流程来理解它。
一、广播接收器的两种注册方法
动态注册
动态注册广播接收器方法：
1.新建一个类继承BroadcastReceiver重写onReceive方法，方法中的内容为接收到广播后要做的事务
2. MainActivity中初始化新建的广播类
3.初始化一个广播过滤器，使用addAction方法指定要接收的广播
4.注册广播接收器，设置接收指定的广播
5.动态注册的需要调用unregisterReceiver()关闭
以下5个系统广播只能动态注册接收，不能静态注册
android.intent.action.SCREEN_ON 亮屏广播
android.intent.action.SCREEN_OFF 灭屏广播
android.intent.action.BATTERY_CHANGED 电池状态广播
android.intent.action.CONFIGURATION_CHANGED 设备当前设置被改变时发出的广播，包括的改变:界面语言，设备方向，等
android.intent.action.TIME_TICK 广播：当前时间已经变化（正常的时间流逝），当前时间改变，每分钟都发送
Myrecive.java
public class Myrecive extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context,"动态广播", Toast.LENGTH_SHORT).show();
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity {
Myrecive bt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化广播
Myrecive bt = new Myrecive();
//建立广播过滤器
IntentFilter itFilter = new IntentFilter();
itFilter.addAction("android.intent.action.SCREEN_ON"); //亮屏时接收广播
//注册广播接收器，设置接收指定的广播
registerReceiver(bt, itFilter);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(bt);
}
}
静态注册
静态广播接收器注册步骤：
1.两种方法注册
a.鼠标右键new一个BroadcastReceiver，重写onReceive方法
b.新建一个类extends BroadcastReceiver，重写onReceive方法，然后在Mainfest文件中添加receiver的代码
2.在Mainfest文件中的receiver里面添加以下代码，name是要接收的广播
3.添加对应的广播接收权限,部分广播需要系统权限才能接收
备注：
安卓8.0后大部分隐式广播无法静态注册接收，详情参考：
https://developer.android.google.cn/guide/components/broadcast-exceptions?hl=zh-cn
MyReceiver.java
public class MyReceiver extends BroadcastReceiver {
**// AIRPLANE_MODE为飞行模式变化广播，此广播安卓8.0以后只能动态注册接收**
private final String ACTION_BOOT = "android.intent.action.AIRPLANE_MODE";
@Override
public void onReceive(Context context, Intent intent) {
if (ACTION_BOOT.equals(intent.getAction())) {
boolean status = intent.getExtras().getBoolean("state");
if (status) {
Toast.makeText(context, "飞行模式开启！", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(context, "飞行模式关闭！", Toast.LENGTH_LONG).show();
}
}
}
}
AndroidManifest.xml
大部分广播是需要接收权限才能接收的，一定不能忘！
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcastreceiver1">
<uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.BroadcastReceiver1">
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true"
android:permission="android.permission.READ_SYNC_SETTINGS">
<intent-filter>
<action android:name="android.intent.action.AIRPLANE_MODE" />
intent-filter>
receiver>
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
intent-filter>
activity>
application>
manifest>
二、发送广播的应用
sendBroadcast发送本地标准广播，app内自发自收
MainActivity.java
public class MainActivity extends AppCompatActivity {
MyReceiver bt;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//注册广播接收器
bt = new MyReceiver();
IntentFilter itFilter = new IntentFilter();
itFilter.addAction("asfgjg");
registerReceiver(bt, itFilter);
Button btn_send = (Button) findViewById(R.id.bt);
btn_send.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//发送广播
sendBroadcast(new Intent("asfgjg"));
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(bt);
}
}
MyReceiver.java
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "asfgjg";
if(actins.equals(intent.getAction())){
Log.d("broadcastreceiver4","接收到本地标准广播！");
}
}
}
localBroadcastManager.sendBroadcast发送本地标准广播，app内自发自收
发送本地广播的方法：
1.注册一个广播接收器
2.使用localBroadcastManager.sendBroadcast发送广播
备注：
发送广播时，intent可带参数
发送的本地广播只能通过动态注册的接收器来接收
MainActivity.java
public class MainActivity extends AppCompatActivity {
private MyReceiver mr;
private LocalBroadcastManager localBroadcastManager;
private IntentFilter intentFilter;
/*
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button bt = (Button) findViewById(R.id.bt);
//注册动态广播接收器
localBroadcastManager = LocalBroadcastManager.getInstance(this);
mr = new MyReceiver();
intentFilter = new IntentFilter();
intentFilter.addAction("aABBD");
localBroadcastManager.registerReceiver(mr, intentFilter);
bt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//发送广播
Intent intent = new Intent("aABBD");
localBroadcastManager.sendBroadcast(intent);
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
localBroadcastManager.unregisterReceiver(mr);
}
}
MyReceiver.java
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "aABBD";
if(actins.equals(intent.getAction())){
Log.d("broadcastreceiver3","接收到本地标准广播！");
}
}
}
发送本地有序广播
首先注册三个广播接收器
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "aABBD";
if(actins.equals(intent.getAction())){
Log.d("MyReceiver","接收到本地发送的有序广播！");
}
}
}
public class MyReceiver2 extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "aABBD";
if(actins.equals(intent.getAction())){
Log.d("MyReceiver2","接收到本地发送的有序广播！");
//截断广播
abortBroadcast();
}
}
}
public class MyReceiver3 extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "aABBD";
if(actins.equals(intent.getAction())){
Log.d("MyReceiver3","接收到本地发送的有序广播！");
}
}
}
解析：
1.有多个广播接收器接收同一个广播时，通过setPriority方法设置广播接收器的优先级调整广播接收的顺序，值越大优先级越高
2.使用sendBroadcast和sendOrderedBroadcast都可以发送有序广播
sendBroadcast和sendOrderedBroadcast的区别
sendBroadcast：无法截断
sendOrderedBroadcast：可以在任意一个广播接收器中使用abortBroadcast()方法截断广播，使优先级低的广播接收器无法接收到广播
MainActivity.java
以下代码中可以分别使用sendBroadcast和sendOrderedBroadcast发送广播测试，通过三个广播接收器打印的log来观察它们接收广播的顺序
public class MainActivity extends AppCompatActivity {
MyReceiver bt;
MyReceiver3 bt3;
MyReceiver2 bt2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//注册广播接收器
bt = new MyReceiver();
bt2 = new MyReceiver2();
bt3 = new MyReceiver3();
IntentFilter itFilter = new IntentFilter();
IntentFilter itFilter2 = new IntentFilter();
IntentFilter itFilter3 = new IntentFilter();
itFilter.addAction("aABBD");
itFilter2.addAction("aABBD");
itFilter3.addAction("aABBD");
itFilter.setPriority(9997);
itFilter2.setPriority(9998);
itFilter3.setPriority(9999);
registerReceiver(bt, itFilter);
registerReceiver(bt2, itFilter2);
registerReceiver(bt3, itFilter3);
Button bt = (Button) findViewById(R.id.bt);
bt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//发送广播
Intent intent = new Intent("aABBD");
// sendBroadcast(intent);
sendOrderedBroadcast(intent, null);
}
});
}
}
接收三方应用发送的广播
首先新建一个项目发送一个全局标准广播
很简单，就两行代码发送
Intent intent = new Intent("aABBD");
sendBroadcast(intent);
然后再新建一个项目注册广播接收器来接收广播
注：静态注册仅安卓8.0之前能接收到，安卓8.0之后只能动态注册才能接收到
动态注册：
还是新建一个类继承BroadcastReceiver
MyReceiver.java
public class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
String actins = "aABBD";
if(actins.equals(intent.getAction())){
Log.d("MyReceiver","接收到全局广播");
}
}
}
然后MainActivity中
MyReceiver bt = new MyReceiver();
IntentFilter itFilter = new IntentFilter();
itFilter.addAction("aABBD");
registerReceiver(bt, itFilter);
静态注册：
第一步仍然是新建一个类继承BroadcastReceiver，代码与动态一样
第二步AndroidManifest.xml文件中注册
<receiver
android:name=".MyReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="aABBD" />
intent-filter>
receiver>
以上代码就完成了，运行两个项目即可看到效果，再一个项目里面发广播，另一个项目里面接收广播
三、其他应用
通过广播打开activity和AlertDialog
广播打开activity和AlertDialog主要是在接收广播之后执行的事务里面，非常简单，所以我直接贴MyReceiver的代码
打开Activity ：
public class MyReceiver extends BroadcastReceiver {
String actions = "aABBD";
@Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(actions)) {
Intent splashIntent = new Intent(context, MainActivity2.class);
splashIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); //新建一个栈存放新打开的activity，否则打不开activity
context.startActivity(splashIntent);
}
}
}
打开AlertDialog：
public class MyReceiver2 extends BroadcastReceiver {
String actions = "aABBD";
@Override
public void onReceive(Context context, Intent intent) {
Log.d("asdg","adsgdasg");
if (intent.getAction().equals(actions)) {
AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(context);
dialogBuilder.setTitle("提示：");
dialogBuilder.setMessage("这是通过广播打开的AlertDialog");
dialogBuilder.setCancelable(false);
dialogBuilder.setPositiveButton("确定",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
AlertDialog alertDialog = dialogBuilder.create();
// 设置对话框类型为TYPE_APPLICATION_OVERLAY，否则无法弹出
alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY);
alertDialog.show();
}
}
}
总结
这里主要是以自己理解的方式写了一些示例代码来加深理解