[英]Java - Reading from a socketchannel
所以我在Java中使用SocketChannels发送和接收项目的数据。 该项目与需要数据ByteBuffer的第3方进行交互,但其前缀为4个字节(即其长度)。
接收时,我将收到一个ByteBuffer,它需要从前面解构4字节的长度并提取数据。 我收到的消息长度不固定。
我当前的实现如下:
public PedResponse send(ByteBuffer message) {
String returnString;
try {
message.flip();
while (message.hasRemaining()) {
socketChannel.write(message);
}
ByteBuffer readBuffer = ByteBuffer.allocate(5000);
int bufferSize = socketChannel.read(readBuffer);
if (bufferSize == -1) {
socketChannel.close();
} else {
readBuffer.flip();
}
returnString = new String(deconstructMessage(readBuffer.array()), "UTF-8").trim();
response = parser.parseResponse(returnString);
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
private ByteBuffer constructMessage(byte[] data) {
// Construct a buffer where we'll put the data to send
ByteBuffer sendBuffer = ByteBuffer.allocate(4 + data.length);
// it's the default, but included for clarity
sendBuffer.order(ByteOrder.BIG_ENDIAN);
// Put the 4-byte length, then the data
sendBuffer.putInt(data.length);
sendBuffer.put(data);
// Extract the actual bytes from our sendBuffer
return sendBuffer;
}
public byte[] deconstructMessage(byte[] data) {
byte[] filteredByteArray = Arrays.copyOfRange(data, 4, data.length - 4);
return filteredByteArray;
}
//Currently not being used.
private byte[] deconstructMessage(byte[] data) {
// Construct a buffer where we'll put the data to send
ByteBuffer receiveBuffer = ByteBuffer.allocate(data.length);
// it's the default, but included for clarity
receiveBuffer.order(ByteOrder.BIG_ENDIAN);
// Get the 4-byte length, then the data
receiveBuffer.getInt(data.length);
receiveBuffer.get(data);
// Extract the actual bytes from our receivedBuffer
byte[] dataReceived = receiveBuffer.array();
return dataReceived;
}
如您所见,我正在创建一个大小为5000的新ByteBuffer,但理想情况下,我不想这样做。 因此,我的问题是,如何不能使用这个过大的ByteBuffer,而只是读取我收到的数据,以便可以使用未使用的deconstruct消息方法?
ByteBuffer具有方法get() ,它从当前位置返回字节。 因此,您可以先读取4个字节并获取大小。
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