提高简单TCP客户端/套接字上的数据传输速度

Question

我有一个家庭作业,通过重定向标准I/O来创建一个带有客户端/服务器TCP套接字对的简单数据传输机制.我实际上有它工作,但当我尝试传输大文件(比如~5g)时,速度会急剧减慢.我正在使用BufferedInputStream和BufferedOutputStream,我想也许我可以在那里进行一些优化.我的服务器的代码是:

private static final int BUF_SIZE = 2047;

public static void main(String[] args) throws IOException{
   /*
    * Attempt to parse command line arguments.
    * @require args[0] is an int
    */
   int port = 0;
   try {
       port = Integer.parseInt(args[0]);
   } catch(NumberFormatException e) {
       System.err.println("Port must be an integer in range 0 - 65535.");
       System.exit(-1);
   }

   /*
    * Bind server socket to specified port number and wait for request.
    * @require port >= 0 && port <= 65535
    */
   ServerSocket welcomeSocket = null;
   welcomeSocket = new ServerSocket(port);
   System.out.println("Now listening on port: " + port);

    /*
     * Accept connection from client socket.
     */
    Socket connectionSocket = null;
    connectionSocket = welcomeSocket.accept();
    System.out.println("Client made connection");

    BufferedInputStream input;
    BufferedOutputStream output;
    if(System.in.available() > 0) {
        input = new BufferedInputStream(System.in, BUF_SIZE);
        output = new BufferedOutputStream(
                connectionSocket.getOutputStream(), BUF_SIZE);
    } else {
        input = new BufferedInputStream(
                connectionSocket.getInputStream(), BUF_SIZE);
        output = new BufferedOutputStream(System.out, BUF_SIZE);
    }

    int place;
    while((place = input.read()) != -1)
        output.write(place);

    input.close();
    output.close();
    welcomeSocket.close();
    connectionSocket.close();
}

客户端代码基本相同.我尝试使用不同的缓冲区大小,包括默认值(通过不指定缓冲区大小),但它们都以大致相同的速度运行.关于如何提高我的表现的任何指示？

感谢您的时间!

Answer 1

while((place = input.read()) != -1)

你从缓冲区一次读取一个字节.调用此方法数百万次的开销相当大.

我建议使用另一个版本将多个字节读入缓冲区(并以相同的方式编写):

public int read(byte[] b,
            int off,
            int len)

例:

byte[] myBuffer = new byte[BUF_SIZE];
while((place = input.read(myBuffer, 0, BUF_SIZE)) != 1)
    output.write(myBuffer, 0, place);