如果这个问题被问了很多次，我很抱歉，但是经过几个小时的谷歌搜索/实验，我还没有解决我的问题。
我正试图通过udp套接字从服务器向客户端发送一个对象（serverplayer），当客户端收到数据包时，我得到一个无效的流头。我不确定什么可以修改数据，导致损坏的/不存在的报头。
发件人线程：
//Thread loop
@Override
public void run()
{
System.out.println("Thread " + threadCount + " running");
//Test object transmission code.
data = new byte[2048];
// -----------------------------------------------------------------------------------
// TRANSMISSION SETUP/OBJECT TRANSFER
try
{
//In case of delay
socket.setSoTimeout(1000);
//Object Transmission setup
ByteArrayOutputStream bStream = new ByteArrayOutputStream();
ObjectOutputStream oo = new ObjectOutputStream(bStream);
oo.writeObject(p);
oo.close();
//Transmit object
data = bStream.toByteArray();
packet = new DatagramPacket(data, data.length, address, 4415);
socket.send(packet);
// -----------------------------------------------------------------------------------
// GAME LOOP
while(socket.getSoTimeout() > 0)
{
}
// -----------------------------------------------------------------------------------
// GET TO THE CHOPPA CODE BELOW
}
catch (SocketException e)
{
System.out.println("Player " + username + " timed out");
}
catch (IOException e)
{
System.out.println("Server: ");
e.printStackTrace();
}
}
客户/接收人：
public MultiplayerGameStart() throws IOException
{
address = InetAddress.getByName("127.0.0.1");
serverip = InetAddress.getByName(NetSettingsManager.ipAdd);
}
@Override
public void run()
{
//Packet byte array
data = new byte[2048];
try
{
//Send connection REQ
socket = new DatagramSocket(4415, address);
data = PacketUtil.intTobyte(NetSettingsManager.NET_FUNCTION.REQ.getFunctionCode(), data.length);
packet = new DatagramPacket(data, data.length, serverip, serverport);
socket.send(packet);
//Wait for ACK
packet = new DatagramPacket(data, data.length);
socket.receive(packet);
//Converts ACK bytes to int to be read. If ACK code is correct, continue.
if(PacketUtil.byteToint(packet.getData()) == NetSettingsManager.NET_FUNCTION.ACK.getFunctionCode())
{
//Returns username to be checked on playerlist.
System.out.println("Logging into server..."); //DEBUG output
data = NetSettingsManager.username.getBytes();
packet = new DatagramPacket(data, data.length, serverip, serverport);
socket.send(packet);
//Stub code below. Will receive player object generated by server.
packet = new DatagramPacket(data, data.length);
socket.receive(packet);
ObjectInputStream iStream = new ObjectInputStream(new ByteArrayInputStream(packet.getData(), packet.getOffset(), packet.getLength()));
//iStream.reset();
ServerPlayer messageClass = (ServerPlayer) iStream.readObject();
iStream.close();
space = new PlayState();
space.addEntity(new ClientPlayer(received));
}
}
catch (IOException e)
{
System.out.println("Client: ");
e.printStackTrace();
}
catch(ClassNotFoundException e)
{
System.out.println("Client: ");
e.printStackTrace();
}
}
serverplayer（注意，我在这个示例中省略了我的函数，但如果需要，我可以提供它们）。
public class ServerPlayer extends ServerEntity implements Serializable
{
int[] material = new int[4];
Chunk pChunk;
public ServerPlayer(String username, float posX, float posY)
{
super(username, posX, posY);
//Material table.
material[0] = 25; //metal
material[1] = 33; //energy
material[2] = 43; //ion
material[3] = 131; //gas
}
}
堆栈跟踪：
java.io.StreamCorruptedException: invalid stream header: 4C756E69
at java.io.ObjectInputStream.readStreamHeader(Unknown Source)
at java.io.ObjectInputStream.<init>(Unknown Source)
at client.multiplayer.MultiplayerGameStart.run(MultiplayerGameStart.java:80)
at java.lang.Thread.run(Unknown Source)
谢谢你的时间：）。
更新
所以在线程中运行我的发送者代码会导致问题。现在我的数据包输出是
server:sent 243 bytes: -84,-19,0,5 | client: received 8 bytes -84, -19, 0, 5
但不幸的是我现在
java.io.EOFException
at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readUTFBody(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readUTF(Unknown Source)
at java.io.ObjectInputStream.readUTF(Unknown Source)
at java.io.ObjectStreamClass.readNonProxy(Unknown Source)
at java.io.ObjectInputStream.readClassDescriptor(Unknown Source)
at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source)
at java.io.ObjectInputStream.readClassDesc(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at client.multiplayer.MultiplayerGameStart.run(MultiplayerGameStart.java:80)
at java.lang.Thread.run(Unknown Source)`
最佳答案
取消对reset()的呼叫。它们不会添加任何内容，我相信对bStream.reset();的服务器端调用将删除创建ObjectOutputStream时写入的头。
另外，在构造ByteArrayInputStream时，应该使用三参数变量，从数据报包传递getOffset()和getLength()。
将来，当你问这样一个问题时，请发布异常的实际堆栈跟踪，以及足够的代码来验证异常是否在你认为的地方发生（在本例中，是完全接收方法）。
编辑：似乎客户端和服务器都在发送和接收到同一端口（4415）。根据您提供的其他调试信息，我相信客户端正在获取它试图发送到服务器的初始数据报。尝试为每个端口使用不同的端口（并使用常量，如CLIENT_PORT和SERVER_PORT来指定它们）。