java - 连接更改接收器在 android 中获得错误 Intent

Question

我正在尝试为我的应用添加一些连接状态感知。使用此处的示例和谷歌的文档，我想出了一个接收器，它可以在连接状态更改时正确显示警报，但也会在创建 Activity 时意外地显示警报。

ConnectStatusReceiver:

package com.zivtaller.placefinder.receivers;

 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.util.Log;
 import android.widget.Toast;

  public class ConnectStatusReceiver extends BroadcastReceiver {

private String TAG = "netReceiver";

public ConnectStatusReceiver() {
    super();
}

@Override
public void onReceive(Context context, Intent arg1) {
    ConnectivityManager cm = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    boolean isConnected = activeNetwork != null
            && activeNetwork.isConnectedOrConnecting();
    if (isConnected) {
        Log.d(TAG, "Data connected");
        Toast.makeText(context, "Data connected", Toast.LENGTH_SHORT)
                .show();
    } else {
        Log.d(TAG, "Data not connected");
        Toast.makeText(context, "Data not connected", Toast.LENGTH_SHORT)
                .show();
    }

}

在activity的onResume()中初始化和注册:

        netReceiver = new ConnectStatusReceiver();
    IntentFilter netFilter = new IntentFilter();
    netFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
    registerReceiver(netReceiver, netFilter);

Answer 1

系统可能生成粘性广播android.net.conn.CONNECTIVITY_CHANGE intents。粘性广播在发送后仍然存在。每当您注册 BroadcastReceiver 以监听粘性广播时，调用 registerReceiver() 时，最近广播的 Intent 将立即传递给接收器。

测试 android.net.conn.CONNECTIVITY_CHANGE 广播是否有粘性的一种简单方法是检查 registerReceiver() 调用的返回值onResume()

netReceiver = new ConnectStatusReceiver();
IntentFilter netFilter = new IntentFilter();
netFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
Intent intent = registerReceiver(netReceiver, netFilter);
if (intent != null) {
    // broadcast is sticky
}

如果您能够确定广播确实具有粘性，那么您遇到的就是预期行为。

参见 what is the difference between sendStickyBroadcast and sendBroadcast in Android .