A simple example of implementing image upload function in Java

import java.io.*;
import java.net.*;
/*
*发送端
*/
class picsend
{
  public static void main(String[] args) throws Exception
  {
    if(args.length!=1)
    {
      System.out.println("请选择一张.jpg图片");
      return;
    }
    File file = new File(args[0]);
    if (!(file.exists() && file.isFile()))
    {
      System.out.println("图片有问题(不是文件或不存在)");
      return;
    }
    if(!file.getName().endsWith(".jpg"))
    {
      System.out.println("图片格式不对，请重新选择图片");
      return;
    }
    if(file.length()>1024*1024*10)
    {
      System.out.println("图片过大，无法上传");
      return;
    }
    Socket s = new Socket("192.168.33.1",10006);//建立服务
    FileInputStream fis = new FileInputStream("d:\\美女.jpg");//读取图片
    OutputStream out = s.getOutputStream();//读到的写入
    byte [] b = new byte[1024];
    int len = 0;
    while((len = fis.read(b))!= -1)
    {
      out.write(b,0,len);
    }
    s.shutdownOutput();//标记结束
    InputStream in = s.getInputStream();//读服务端返回数据
    byte [] bin = new byte[1024];
    int num = in.read(bin);
    System.out.println(new String(bin,0,num));
    fis.close();
    s.close();
  }
}
class picThread implements Runnable
{
  private Socket s;
  picThread(Socket s)
  {
    this.s = s;
  }
  public void run()
  {
    int count = 1;
    String ip = s.getInetAddress().getHostAddress();//得到ip
    try
    {
      System.out.println(ip+".............connect");
      InputStream in = s.getInputStream();//读到流中数据
      File file = new File(ip+"("+(count)+")"+".jpg");
      while(file.exists())//判断文件是否存在
        file = new File(ip+"("+(count++)+")"+".jpg");
      FileOutputStream fos = new FileOutputStream(file);//写入
      byte [] b = new byte[1024];
      int len = 0;
      while((len = in.read(b))!=-1)
      {
        fos.write(b,0,len);
      }
      OutputStream out = s.getOutputStream();//写入服务端传过来数据
      out.write("上传成功！".getBytes());
      fos.close();
      s.close();
    }
    catch (Exception e)
    {
      throw new RuntimeException("上传失败");
    }
  }
}
/*
*服务端
*/
class picrece
{
  public static void main(String[] args) throws Exception
  {
    ServerSocket ss = new ServerSocket(10006);
    while(true)
    {
      Socket s = ss.accept();//接收
      new Thread(new picThread(s)).start();
    }
  }
}