Here is some code.
This is edited version of code that I use to read data off a socket connection. I've editted to simplify it slightly, I hope I have not broken it.
I always know how much data to read, and I call this routine to read it all. I used to have something simpler but I found that I needed to repeat reads sometimes, especially with the newer OS's. In other words, I would get some of the bytes I expected, then the read would complete , without an error. Where I know there is more data expected, I re-issue the read.
I say I always know how much data. I make sure of this in my communication with any server. Typically the server will send me a length in 4 bytes, and then the data. So I will call this routine twice, the first for 4 bytes, and then I convert those bytes to a int, and call this routine again for the actual data.
Hope this helps.
private static final int readLength(final InputStream _in, final byte [] buffer, final int startIndex, final int lengthExpected) throws IOException {
int indexOfNextByte = startIndex;
int lengthLeftToRead = lengthExpected;
int lengthActuallyRead = 0;
while ( lengthLeftToRead > 0 ) {
lengthActuallyRead = _in.read(buffer, indexOfNextByte, lengthLeftToRead);
if ( lengthActuallyRead < 0 ) {
System.out.println("Unexpected EOF, " + lengthLeftToRead + " bytes to read.");
throw new RuntimeException("Unexpected Receive EOF");
} else
if ( lengthActuallyRead == 0 ) {
System.out.println("Expected data, got 0 bytes, " + lengthLeftToRead + " bytes to read.");
throw new RuntimeException("Unexpected Receive 0 bytes");
} else {
lengthLeftToRead = lengthLeftToRead - lengthActuallyRead;
indexOfNextByte = indexOfNextByte + lengthActuallyRead;
if ( lengthLeftToRead > 0 ) {
System.out.println("Repeat Read request, got " + lengthActuallyRead + ", remaining " + lengthLeftToRead);
}
}
}
byte [] partialBuffer = Arrays.copy(buffer, startIndex, lengthExpected);
System.out.println("Read:X\"" + byteArrayToHexString(partialBuffer) + "\".");
return lengthExpected - lengthLeftToRead;
}
