学步园

代码如下：

void pipe(InputStream is0, InputStream is1, OutputStream os0,
			OutputStream os1) throws IOException {
		try {
			int ir;
			byte bytes[] = new byte[BUFSIZ];
			while (true) {
				try {
					if ((ir = is0.read(bytes)) > 0) {
						os0.write(bytes, 0, ir);
						if (logging)
							writeLog(bytes, 0, ir, true);
					} else if (ir < 0)
						break;
				} catch (InterruptedIOException e) {
				}
				try {
					if ((ir = is1.read(bytes)) > 0) {
						os1.write(bytes, 0, ir);
						if (logging)
							writeLog(bytes, 0, ir, false);
					} else if (ir < 0)

						break;			
				} catch (InterruptedIOException e) {
				}
			}
		} catch (Exception e0) {
			System.out.println("Pipe异常: " + e0);
		}
	}

但是弄不清为什么 ir=inputstream.read()<0不表示读完数据？求大神解释。