我正在开始一些Java NIO编程，并且正在构建两个单独的Java程序。一种是创建一些随机数据通过UDP发送，另一种是接收这些数据，并可能对其执行一些处理。
在每个类中，我已经定义了要发送/接收的数据的SIZE，以及一次（每个数据包）以8个字节发送或接收的字节数。当我有一个1024字节的SIZE时，我可以打开接收器（默认等待一些数据包到达），之后我打开发送数据包的发送器，接收器正确接收这些数据包并终止所有数据包收到数据包。然后我尝试将SIZE设置为10兆字节。我启动接收器，然后启动发送器。发件人似乎工作正常并在几秒钟后终止。接收器开始工作并继续读取多个数据包（我在代码周围放了一些printlns）。但是，在此过程中的某个地方，接收器似乎挂起并停止接收更多数据包。我不知道挂起的位置，只是在缓冲区被清除以进行新读取之后才会发生。
也许我错误地使用了这个库。非常感谢任何帮助。
发件人类称为UDPSender，如下所示：
public class UDPSender {
public static void main(String[] args) {
try {
// Generate some data to send
int SIZE=1024*1024*10;
int bufferBytes = 8;
byte[] b = new byte[SIZE];
new Random().nextBytes(b);
String value = new String(b);
//System.out.println(value);
// Create Datagram channel for sending UDP packets
DatagramChannel sendingChannel = DatagramChannel.open();
// Bind the channel to a specific sending socket address and port
InetSocketAddress sendSocket = new InetSocketAddress("127.0.0.1", 9999);
sendingChannel.socket().bind(sendSocket);
//Target socket address
InetSocketAddress targetSocket = new InetSocketAddress("127.0.0.1", 8888);
//loop to send bufferBytes bytes at a time
int location = 0;
int bytesSent = 0;
long startTime=0; long endTime=0; long elapsedTime=0; // for speed benchmarking
startTime = System.nanoTime();
for (int i = 1; i <= SIZE / bufferBytes; i++) {
//System.out.println(i);
ByteBuffer buf = ByteBuffer.allocate(bufferBytes);
buf.clear();
buf.put(Arrays.copyOfRange(b, location, location + bufferBytes));
location = location + bufferBytes;
buf.flip();
bytesSent = bytesSent + sendingChannel.send(buf, targetSocket);
}
endTime = System.nanoTime();
elapsedTime = endTime - startTime;
double elapsedTimeMs = elapsedTime / 1000000.0;
System.out.println("Elapsed:" + elapsedTimeMs + " msec");
} catch (IOException ex) {
Logger.getLogger(UDPSender.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
第二个类叫做UDPReceiver，如下所示：
public class UDPReceiver {
public static void main(String[] args) {
try {
int SIZE=1024*1024*10;
int bufferBytes = 8;
int packet_max = SIZE/bufferBytes;
// Create Datagram channel for receiving UDP packets
DatagramChannel receivingChannel = DatagramChannel.open();
// Bind the channel to a specific receiving socket address and port
InetSocketAddress receiveSocket = new InetSocketAddress("127.0.0.1",8888);
receivingChannel.socket().bind(receiveSocket);
// Set up address of send
InetSocketAddress sendSocket = new InetSocketAddress("127.0.0.1",9999);
// Connect our receiving socket to their sending socket address
receivingChannel.connect(sendSocket);
long startTime=0; long endTime=0; long elapsedTime=0; // for speed benchmarking
byte[] b = new byte[SIZE]; //receiving storage
int packets=0; int location=0; int bytesCount; //byte[] indexes
boolean clockStart=false;
//try indirect ByteBuffer
System.out.println("Indirect ByteBuffer()");
ByteBuffer buf = ByteBuffer.allocate(bufferBytes);
packets=0; location=0; bytesCount = 0; clockStart=false;
while ((bytesCount = receivingChannel.read(buf)) > 0) { // Read data from file into ByteBuffer
System.out.println(".");
if(clockStart==false){
startTime = System.nanoTime();
clockStart=true;
}
// flip the buffer which set the limit to current position, and position to 0.
buf.flip(); System.out.println("..");
System.arraycopy(buf.array(), 0, b, location, buf.capacity()); System.out.println("..."); // Write data from ByteBuffer to bytearray
location=location+bufferBytes; System.out.println("....");
buf.clear(); System.out.println("....."); // For the next read
packets = packets+1; System.out.println("......");
if(packets==packet_max){
System.out.println(".......");
System.out.println(packets);
break;
}
}
endTime = System.nanoTime();
elapsedTime = endTime - startTime;
System.out.println("ByteBuffer() Elapsed Time is " + (elapsedTime / 1000000.0) + " msec");
} catch (IOException ex) {
System.out.println(ex.toString());
//Logger.getLogger(UDPReceiver.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
答案 0 :(得分：0)
它没有挂起＆＃39;它阻止，它就是这样做的，因为你试图读取特定数量的数据包而不考虑这个事实UDP是不可靠的。当您丢失数据包时，您的发送方和接收方都不会知道，因此您的发送方不会重新发送，并且您的接收方一直在尝试读取所有数据包，这些数据包永远不会到达