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我正在尝试开发一个 android 应用程序来测量网络的 QoS。该应用程序将 UDP 数据包发送到我系统上运行的 UDP 服务器。由于这是一个长时间运行的过程，我在一个扩展 IntentService 的类中实现了 UDP 连接。使用 IntentService 背后的原因是我需要将一些参数传递给服务。我的活动中有一个 BroadcastReceiver，它侦听来自 IntentService 的消息并将其打印出来。我的问题是，虽然 IntentService 运行顺利，但活动没有收到来自它的消息。我是android开发的新手，所以请原谅我缺乏理解，任何指导/建议将不胜感激。我在下面发布了我的代码的某些部分。Logcat 没有显示任何错误。我见过intent.setAction()在某些示例中使用了方法，但我不太清楚如何在我的情况下使用它。

BroadcastReceiver（在我的 Activity 类中定义）

public class UdpResponseReceiver extends BroadcastReceiver {
 public static final String ACTION_RESP = "com.example.udpmessageclient.intent.action.MESSAGE_PROCESSED";
    @Override
    public void onReceive(Context context, Intent intent) {

        System.out.println(UdpService.PARAM_OUT_MSG);

    }

我已经注册了接收器：

IntentFilter filter = new IntentFilter(UdpResponseReceiver.ACTION_RESP);
filter.addCategory(Intent.CATEGORY_DEFAULT);
receiver = new UdpResponseReceiver();
registerReceiver(receiver, filter);

IntentService 类：

public class UdpService extends IntentService {

//..variable declarations

public UdpService() {
    // TODO Auto-generated constructor stub
    super("UdpService");
}

@Override
protected void onHandleIntent(Intent intent) {
    // TODO Auto-generated method stub
    host = intent.getStringExtra("host");
    port = intent.getIntExtra("port", 4000);
    pType= intent.getIntExtra("pType", 0);
    delay = intent.getIntExtra("delay", 0);
    msg= intent.getStringExtra("msg");
    broadcastIntent = new Intent();
    broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);
    broadcastIntent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES); 

    try {
        addr = InetAddress.getByName(host);
        // addr=InetAddress.getLocalHost();
        socket = new DatagramSocket();
        // socket.connect(addr,port);

        System.out.println("\nSocket Connected");
    } catch (Exception e) {
        System.out.println("\nConnection failed");
        return;
    }

    send=true;
    switch (pType) {
    case 0:
        while (send) {
            sendPacket(msg);
        }
    case 1:
        while (send) {
            try {
                Thread.currentThread().sleep(delay);
            } catch (Exception e) {
            }
            sendPacket(msg);
        }
    case 2:
        while (send) {
            int u = want(30);
            String data1 = "";
            while ((u--) > 0)
                data1 = data1 + msg;
            sendPacket(data1);
        }
    case 3:
        while (send) {
            int u = want(30);
            System.out.println(u);
            String data1 = "";
            while ((u--) > 0)
                data1 = data1 + msg;
            System.out.println("data length :" + data1.length());
            try {
                Thread.currentThread().sleep(delay);
            } catch (Exception e) {
            }
            sendPacket(data1);
        }

    }
}
public void onDestroy(){
    super.onDestroy();
    send=false;
    socket.close();
    socket=null;

}
void sendPacket(String text) {

    try {
        System.out.println("\nClient:: Sending packet: " + " to " + addr
                + port);
        byte[] data = text.getBytes();
        spacket = new DatagramPacket(data, data.length, addr, port);
        socket.send(spacket);
        String resultTxt="Sent Packet at:"+DateFormat.format("MM/dd/yy h:mmaa", System.currentTimeMillis());

// this is where I am trying to send message back to the activity

    broadcastIntent.putExtra(PARAM_OUT_MSG, resultTxt);
        sendBroadcast(broadcastIntent);
    } catch (Exception e) {
        System.out.println("Error:" + e.getMessage());
        e.printStackTrace();
        return;
    }
}

}

服务停止时的logcat错误消息：

01-14 15:53:41.446: W/System.err(1176): java.lang.NullPointerException
01-14 15:53:41.456: W/System.err(1176):     at com.example.udpmessageclient.UdpService.sendPacket(UdpService.java:123)
01-14 15:53:41.466: W/System.err(1176):     at com.example.udpmessageclient.UdpService.onHandleIntent(UdpService.java:74)
01-14 15:53:41.466: W/System.err(1176):     at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
01-14 15:53:41.466: W/System.err(1176):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-14 15:53:41.466: W/System.err(1176):     at android.os.Looper.loop(Looper.java:137)
01-14 15:53:41.476: W/System.err(1176):     at android.os.HandlerThread.run(HandlerThread.java:60)
4

1 回答 1

2

将 UdpService 的代码更改为...

broadcastIntent = new Intent(UdpResponseReceiver.ACTION_RESP); // You forgot to add your custom intent filter
broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);
//broadcastIntent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES); // I don't think you really need it. So you can remove this flag.

更新 

public static final String ACTION_RESP = "com.example.udpmessageclient.intent.action.MESSAGE_PROCESSED";

private final BroadcastReceiver UdpResponseReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {

            //TODO handle results

        }
    };

并将其注册为 

registerReceiver(UdpResponseReceiver, new IntentFilter(ACTION_RESP))
于 2013-01-14T09:39:00.667 回答