在Android设备中接收UDP广播时丢包 [英] Packet loss while receiving UDP broadcast in android device
问题描述
为了接收从服务器到android设备的UDP广播数据包，我使用了服务类并在线程中侦听数据包.它成功接收到数据包.问题是，如果同时从服务器发送多个数据包，则会导致数据包丢失.
我什至尝试使用队列并在单独的线程中处理接收到的数据包，然后我也没有得到数据包.我是网络编程的新手，将不胜感激
void startListenForUdpBroadcast() {
UDPBroadcastThread = new Thread(new Runnable() {
public void run() {
try {
InetAddress broadcastIP = InetAddress.getByName(UdpConstants.IP_ADDRESS);
Integer port = UdpConstants.RECEIVER_PORT;
while (shouldRestartSocketListen) {
listenAndWaitAndThrowIntent(broadcastIP, port);
}
} catch (Exception e) {
Log.i("UDP", "no longer listening for UDP broadcasts cause of error " + e.getMessage());
}
}
});
UDPBroadcastThread.setPriority(Thread.MAX_PRIORITY); //Setting The Listener thread to MAX PRIORITY to minimize packet loss.
UDPBroadcastThread.start();
}
此代码侦听新数据包并推送到队列
private void listenAndWaitAndThrowIntent(InetAddress broadcastIP, Integer port) throws Exception {
byte[] recvBuf = new byte[64000];
if (socket == null || socket.isClosed()) {
socket = new DatagramSocket(port, broadcastIP);
socket.setBroadcast(true);
}
//socket.setSoTimeout(1000);
DatagramPacket packet = new DatagramPacket(recvBuf, recvBuf.length);
socket.receive(packet);
messQueue.add(packet);
}
这将检查队列中是否有新消息并对其进行处理
/**
* @purpose Checking queue and If anything is added to the queue then broadcast it to UI
*/
private void checkQueue() {
queueThread = new Thread(new Runnable() {
public void run() {
try {
while (shouldRestartSocketListen) {
if (!messQueue.isEmpty()) {
broadcastIntent(messQueue.poll());
}
}
} catch (Exception e) {
}
}
});
queueThread.start();
}
我认为您的问题主要是您在wifi上使用了Udp广播.
他们有两个非常有据可查的答案，为什么这是一种非常慢的操作方式，以及为什么会有更多的数据包丢失:
我为解决极慢的带宽所做的事情是某种多单播协议:
- 管理已连接的客户端列表.
- 通过发送呼叫，将服务器中的每个数据包分别发送给所有客户端.
这是java中的代码:
DatagramPacket packet = new DatagramPacket(buffer, size);
packet.setPort(PORT);
for (byte[] clientAddress : ClientsAddressList) {
packet.setAddress(InetAddress.getByAddress(clientAddress));
transceiverSocket.send(packet);
}
For receiving UDP broadcast packets from the server to an android device, i used a service class and listen for packets in a thread. It receives the packet successfully. The problem is that if multiple packets are being sent from the server in the same time then packet loss will be the result.
I even tried with a queue and processing the received packets in separate thread then also i am not getting the packet. I am completely new to network programming any help would be widely appreciated
void startListenForUdpBroadcast() {
UDPBroadcastThread = new Thread(new Runnable() {
public void run() {
try {
InetAddress broadcastIP = InetAddress.getByName(UdpConstants.IP_ADDRESS);
Integer port = UdpConstants.RECEIVER_PORT;
while (shouldRestartSocketListen) {
listenAndWaitAndThrowIntent(broadcastIP, port);
}
} catch (Exception e) {
Log.i("UDP", "no longer listening for UDP broadcasts cause of error " + e.getMessage());
}
}
});
UDPBroadcastThread.setPriority(Thread.MAX_PRIORITY); //Setting The Listener thread to MAX PRIORITY to minimize packet loss.
UDPBroadcastThread.start();
}
This code listens for new packets and pushes to queue
private void listenAndWaitAndThrowIntent(InetAddress broadcastIP, Integer port) throws Exception {
byte[] recvBuf = new byte[64000];
if (socket == null || socket.isClosed()) {
socket = new DatagramSocket(port, broadcastIP);
socket.setBroadcast(true);
}
//socket.setSoTimeout(1000);
DatagramPacket packet = new DatagramPacket(recvBuf, recvBuf.length);
socket.receive(packet);
messQueue.add(packet);
}
This checks the queue for new messages and process it
/**
* @purpose Checking queue and If anything is added to the queue then broadcast it to UI
*/
private void checkQueue() {
queueThread = new Thread(new Runnable() {
public void run() {
try {
while (shouldRestartSocketListen) {
if (!messQueue.isEmpty()) {
broadcastIntent(messQueue.poll());
}
}
} catch (Exception e) {
}
}
});
queueThread.start();
}
I think your problem is mainly that you use Udp Broadcast over wifi.
Their are two very well documented answers why this is a very slow way to operate and why there are much more packet losts:
The thing I did to solve the extremely slow bandwidth was some kind of multi-unicast protocol:
- Manage the list of clients you have connected.
- Send each packet you have in your server to all of your clients separately with send call.
This is the code in java:
DatagramPacket packet = new DatagramPacket(buffer, size);
packet.setPort(PORT);
for (byte[] clientAddress : ClientsAddressList) {
packet.setAddress(InetAddress.getByAddress(clientAddress));
transceiverSocket.send(packet);
}
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