问题:

How to make the PrintWriter to write UTF-8?

pstream = new PrintWriter(csocket.getOutputStream(), true);
String res = "some string";
pstream.println(res); // here I want to output string as UTF-8

回答1:

Use an OutputStreamWriter:

pstream = new PrintWriter(new OutputStreamWriter(
    csocket.getOutputStream(), StandardCharsets.UTF_8), true)

回答2:

Look at Java: Difference between PrintStream and PrintWriter discussion.

To be quick: you can use -Dfile.encoding=utf8 JVM parameter or method suggested in the discussion (see second answer).

回答3:

Don't user PrintWriter. If you need UTF-8 encoding, just write direct to the OutputStream.

csocket.getOutputStream().write(res.getBytes("UTF-8"));

回答4:

PrintWriter out1 = null;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
    out1 = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), StandardCharsets.UTF_8),true);
} else { 
    out1 = new PrintWriter(new OutputStreamWriter(socket.getOutputStream(), "UTF8"), true);
}