InputStream.read（byte [] b）返回意外的字节

Question

I'm using bytesCount = InputStream.read(byteArray) to read data from a client:

My Server:

InputStream IS = Connection.getInputStream();
byte[] InData = new byte[1024];
int bytesCount = IS.read(InData);    

My Client:

ObjectOutputStream OOS = null;
try {
    OOS = new ObjectOutputStream(connection.getOutputStream());
} catch (Exception e) {}
OutputStreamWriter OSW = new OutputStreamWriter(OOS);
try {           
    OSW.write("ABC");
    OSW.flush();
} catch (Exception e) {}    

As you can see, the client sends a string "ABC", but the byte array that the server receives is InData = [-84, -19, 0, 5, 119, 3, 65, 66, 67, 0, 0, 0, ...] and bytesCount = 9

What are those first 6 bytes?

Answer 1

It's the ObjectOutputStreamHeader, see writeStreamHeader() here: http://developer.classpath.org/doc/java/io/ObjectOutputStream-source.html

If you want to serialize the string as UTF8, just use a regular OutputStreamWriter (not an ObjectOutputStream) with UTF8 encoding and write the string:

OutputStreamWriter ows = new OutputStreamWriter(connection.getOutputStream(), "UTF-8");
osw.write("ABC");