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java – android socket DataOutputStream.writeUTF

Posted by: admin June 15, 2020 Leave a comment

Questions:

I write socket client:

clientSocket = new Socket("192.168.1.102", 15780);
outToServer = new DataOutputStream(clientSocket.getOutputStream());

All works. But I wont to send to server UTF-8 format messages and do so:

outToServer.writeBytes("msg#");//server tag
outToServer.writeUTF("hello");
//outToServer.writeUTF(str); //or another string
outToServer.writeBytes("\n");
outToServer.flush();

Messages become such:

secret byte

Tell me please why? How correctly send UTF messages?

How to&Answers:

writeUTF() documentation says:

First, two bytes are written to the output stream as if by the writeShort method giving the number of bytes to follow. This value is the number of bytes actually written out, not the length of the string.

You can encode the string as utf-8 yourself and then send the resulting byte array to the server using write():

byte[] buf = "hello".getBytes("UTF-8");
outToServer.write(buf, 0, buf.length);