文件　到　byte数组的问题

为什么输出的都是０
File f = new File("temp//33.zip");
            FileOutputStream fos = new FileOutputStream(f);byte[] byteBuffer = new byte[1024];
            fos.write(byteBuffer,0,byteBuffer.length);
            for (int k = 0; k < byteBuffer.length; k++) {
                System.out.println("my_byte " + byteBuffer[k]);
            }