java - 如何在文件到OutputStream之前读出一个字节数组

Question

我想将文件大小和另一个整数、来自和 android 平板电脑的平板序列号发送到运行 Windows 7 的服务器：

我的客户端代码有什么问题以及如何使服务器接受不同字节的数据流？

安卓平板客户端代码

   try {

                byte[] bytes = new byte[(int) length];
                fis = new FileInputStream(file2);
                bis = new BufferedInputStream(fis);
                bos = new BufferedOutputStream(socket.getOutputStream());

                int count;

                // convert integer to byte
                ByteArrayOutputStream baos = new ByteArrayOutputStream();
                DataOutputStream dos = new DataOutputStream(baos);
                dos.writeInt(1992);
                byte[] preByte = baos.toByteArray();

                // the first byte that sends the tablet serial number and the size of the next file it is going to send
                bis.read(preByte);

                // the next sent is the file itself which is a database file
                while ((count = bis.read(bytes)) > 0) {
                    bos.write(bytes, 0, count);
                }

                fis.close();
                bis.close();
                fis = null;
                bis = null;
                socket.close();

将接收这两个文件的服务器代码

        fos = new FileOutputStream(file);
        bos = new BufferedOutputStream(fos);

        System.out.println("streams are setup from new thread\n");

        is = socket.getInputStream();
        bufferSize = socket.getReceiveBufferSize();

        buffer = new byte[bufferSize];

        while ((count = is.read(buffer)) > 0) {
            bos.write(buffer, 0, count);
        } // end while

        bos.flush();
        bos.close();
        is.close();

Answer 1

尝试这个

dos = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
dos.writeLong(length);
dos.writeInt(1992);
for (int b; (b = bis.read()) != -1;) {
   dos.write(b);
}

...

dis = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
long length = dis.readLong();
int serialNumber = dis.readInt();
... read bytes

Answer 2

似乎您正在读取 preByte 数组而不是将其写入输出流：

bis.read(preByte);

你可能的意思是：

bos.write(preByte);

Answer 3

你根本不需要ByteArrayOutputStream。只需将 a 包裹DataOutputStream起来BufferedOutputStream,并通过DataOutputStream.