android中broadcastreceiver的用法-代码中注册
界面如下：
问题1：点击“解绑广播接收器“后再次点击”解绑广播接收器“后，程序崩溃，log信息如下：
08-04 05:04:35.420: E/AndroidRuntime(5521): FATAL EXCEPTION: main
08-04 05:04:35.420: E/AndroidRuntime(5521): java.lang.IllegalArgumentException: Receiver not registered: com.jinhoward.broadcast.receiver.SecondReceiver@40cfec98
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.app.LoadedApk.forgetReceiverDispatcher(LoadedApk.java:657)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.app.ContextImpl.unregisterReceiver(ContextImpl.java:1339)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:445)
08-04 05:04:35.420: E/AndroidRuntime(5521): at com.jinhoward.broadcast.activity.MainActivity$3.onClick(MainActivity.java:62)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.view.View.performClick(View.java:4204)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.view.View$PerformClick.run(View.java:17355)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.os.Handler.handleCallback(Handler.java:725)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.os.Handler.dispatchMessage(Handler.java:92)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.os.Looper.loop(Looper.java:137)
08-04 05:04:35.420: E/AndroidRuntime(5521): at android.app.ActivityThread.main(ActivityThread.java:5041)
08-04 05:04:35.420: E/AndroidRuntime(5521): at java.lang.reflect.Method.invokeNative(Native Method)
08-04 05:04:35.420: E/AndroidRuntime(5521): at java.lang.reflect.Method.invoke(Method.java:511)
08-04 05:04:35.420: E/AndroidRuntime(5521): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-04 05:04:35.420: E/AndroidRuntime(5521): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-04 05:04:35.420: E/AndroidRuntime(5521): at dalvik.system.NativeStart.main(Native Method)
后来排查代码百度找到问题答案，通过一个布尔变量来判断广播接收器是否已经注册。
package com.jinhoward.broadcast.activity;
import android.app.Activity;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
import com.jinhoward.broadcast.receiver.SecondReceiver;
public class MainActivity extends Activity {
protected static final String ACTION = "com.jinhoward.broadcast.ACTION";
private Button btnBroadcast;
private Button registerReceiver;
private Button unregisterReceiver;
private SecondReceiver receiver;
private Boolean registerBoolean;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnBroadcast = (Button) findViewById(R.id.btnBroadcast);
btnBroadcast.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.setAction(ACTION);
sendBroadcast(intent);
}
});
registerReceiver = (Button) findViewById(R.id.btnregisterReceiver);
registerReceiver.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
receiver = new SecondReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION);
Log.i("MyReceiver", "注册广播接收器！");
registerReceiver(receiver, filter);
registerBoolean = true;
}
});
unregisterReceiver = (Button) findViewById(R.id.btnunregisterReceiver);
unregisterReceiver.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
//第一次进入到应用程序后就点击“解绑广播接收器”按钮会崩溃，此行代码处理此异常。
if (receiver == null) {
Toast.makeText(MainActivity.this, "广播接收器为空！",Toast.LENGTH_SHORT).show();
}
//点击“解绑广播接收器“后再次点击”解绑广播接收器“后，程序崩溃，错误log信息为：FATAL EXCEPTION: main
//08-04 05:04:35.420: E/AndroidRuntime(5521): java.lang.IllegalArgumentException: Receiver not registered:
else if (registerBoolean == false) {
Toast.makeText(MainActivity.this, "广播接收器未注册！",Toast.LENGTH_SHORT).show();
}else{
unregisterReceiver(receiver);
registerBoolean = false;
Log.i("MyReceiver", "广播接收器已经取消注册！");
}
}
});
}
}
package com.jinhoward.broadcast.receiver;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
/**
* @author jinhoward
* @blog http://blog.csdn.net/jinhoward
*/
public class SecondReceiver extends BroadcastReceiver
{
private static final String TAG = "MyReceiver";
public SecondReceiver()
{
Log.i(TAG, "广播接收器的构造函数");
}
@Override
public void onReceive(Context context, Intent intent)
{
Log.i(TAG, "广播接收器接收到广播:"+intent.getAction());
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jinhoward.broadcast.activity"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="8" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name="com.jinhoward.broadcast.activity.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>
</application>
</manifest>