package sockets;import java.net.*;import java.io.*;public class SocketsServerFile {  public static void main(String[] args) throws IOException {    //聲明客戶端寫出類    PrintWriter clientPrintWriter = null;    //聲明客戶端讀入類    InputStream clientInputStream = null;    //創建新文件newDemo.jpg    FileOutputStream fileOutputStream = new FileOutputStream("newDemo.jpg");    //創建服務接口    ServerSocket serverSocket = null;    try {      //應用端口2223      serverSocket = new ServerSocket(2223);    } catch (IOException e) {      e.printStackTrace();      System.exit(0);    }    System.out.println("成功創建2223端口的服務器.");    //創建Socket的客戶接口,當有客戶端的程序訪問該服務接口時激活該類    Socket clientSocket = null;    try {      //通過accept()方法使服務器與客戶端的Socket接口建立聯系      clientSocket = serverSocket.accept();    } catch (IOException e) {      e.printStackTrace();      System.exit(0);    }    //取得客戶端的寫出類    clientPrintWriter = new PrintWriter(clientSocket.getOutputStream(), true);    //取得客戶端的讀入類    clientInputStream = clientSocket.getInputStream();    //當有客戶端的程序進入時顯示歡迎信息    clientPrintWriter.println("服務端傳入的字符串");    //讀入客戶端信息    int c;    while ( (c = clientInputStream.read()) != -1) {      //使用write()方法向文件寫入信息      fileOutputStream.write(c);    }    System.out.println("完成文件的讀入.");    //關閉客戶端的寫出器    clientPrintWriter.close();    //關閉客戶端的讀入器    clientInputStream.close();    //關閉文件寫出類    fileOutputStream.close();    //關閉客戶端接口    clientSocket.close();    //關閉服務端接口    serverSocket.close();  }}