Java基于Socket文件传输示例

最近需要进行网络传输大文件，于是对基于socket的文件传输作了一个初步的了解。在一位网友提供的程序基础上，俺进行了一些加工，采用了缓冲输入/输出流来包装输出流，再采用数据输入/输出输出流进行包装，加快传输的速度。废话少说，先来看服务器端的程序。

1.服务器端

package  sterning;

import  java.io.BufferedInputStream;
import  java.io.DataInputStream;
import  java.io.DataOutputStream;
import  java.io.File;
import  java.io.FileInputStream;
import  java.net.ServerSocket;
import  java.net.Socket;

public   class  ServerTest  {
     int  port  =   8821 ;

     void  start()  {
        Socket s  =   null ;
         try   {
            ServerSocket ss  =   new  ServerSocket(port);
             while  ( true )  {
                 //  选择进行传输的文件
                String filePath  =   " D://lib.rar " ;
                File fi  =   new  File(filePath);

                System.out.println( " 文件长度: "   +  ( int ) fi.length());

                 //  public Socket accept() throws
                 //  IOException侦听并接受到此套接字的连接。此方法在进行连接之前一直阻塞。

                s  =  ss.accept();
                System.out.println( " 建立socket链接 " );
                DataInputStream dis  =   new  DataInputStream( new  BufferedInputStream(s.getInputStream()));
                dis.readByte();

                DataInputStream fis  =   new  DataInputStream( new  BufferedInputStream( new  FileInputStream(filePath)));
                DataOutputStream ps  =   new  DataOutputStream(s.getOutputStream());
                 // 将文件名及长度传给客户端。这里要真正适用所有平台，例如中文名的处理，还需要加工，具体可以参见Think In Java 4th里有现成的代码。
                ps.writeUTF(fi.getName());
                ps.flush();
                ps.writeLong(( long ) fi.length());
                ps.flush();

                 int  bufferSize  =   8192 ;
                 byte [] buf  =   new   byte [bufferSize];

                 while  ( true )  {
                     int  read  =   0 ;
                     if  (fis  !=   null )  {
                        read  =  fis.read(buf);
                    }

                     if  (read  ==   - 1 )  {
                         break ;
                    }
                    ps.write(buf,  0 , read);
                }
                ps.flush();
                 //  注意关闭socket链接哦，不然客户端会等待server的数据过来，
                 //  直到socket超时，导致数据不完整。                
                fis.close();
                s.close();                
                System.out.println( " 文件传输完成 " );
            }

        }   catch  (Exception e)  {
            e.printStackTrace();
        }
    }

     public   static   void  main(String arg[])  {
         new  ServerTest().start();
    }
}

2.socket的Util辅助类

package  sterning;

import  java.net. * ;
import  java.io. * ;

public   class  ClientSocket  {
     private  String ip;

     private   int  port;

     private  Socket socket  =   null ;

    DataOutputStream out  =   null ;

    DataInputStream getMessageStream  =   null ;

     public  ClientSocket(String ip,  int  port)  {
         this .ip  =  ip;
         this .port  =  port;
    }

     /**
     * 创建socket连接
     * 
     *  @throws  Exception
     *             exception
      */
     public   void  CreateConnection()  throws  Exception  {
         try   {
            socket  =   new  Socket(ip, port);
        }   catch  (Exception e)  {
            e.printStackTrace();
             if  (socket  !=   null )
                socket.close();
             throw  e;
        }   finally   {
        }
    }

     public   void  sendMessage(String sendMessage)  throws  Exception  {
         try   {
            out  =   new  DataOutputStream(socket.getOutputStream());
             if  (sendMessage.equals( " Windows " ))  {
                out.writeByte( 0x1 );
                out.flush();
                 return ;
            }
             if  (sendMessage.equals( " Unix " ))  {
                out.writeByte( 0x2 );
                out.flush();
                 return ;
            }
             if  (sendMessage.equals( " Linux " ))  {
                out.writeByte( 0x3 );
                out.flush();
            }   else   {
                out.writeUTF(sendMessage);
                out.flush();
            }
        }   catch  (Exception e)  {
            e.printStackTrace();
             if  (out  !=   null )
                out.close();
             throw  e;
        }   finally   {
        }
    }

     public  DataInputStream getMessageStream()  throws  Exception  {
         try   {
            getMessageStream  =   new  DataInputStream( new  BufferedInputStream(socket.getInputStream()));
             return  getMessageStream;
        }   catch  (Exception e)  {
            e.printStackTrace();
             if  (getMessageStream  !=   null )
                getMessageStream.close();
             throw  e;
        }   finally   {
        }
    }

     public   void  shutDownConnection()  {
         try   {
             if  (out  !=   null )
                out.close();
             if  (getMessageStream  !=   null )
                getMessageStream.close();
             if  (socket  !=   null )
                socket.close();
        }   catch  (Exception e)  {

        }
    }
}

3.客户端

package  sterning;

import  java.io.BufferedOutputStream;
import  java.io.DataInputStream;
import  java.io.DataOutputStream;
import  java.io.FileOutputStream;

public   class  ClientTest  {
     private  ClientSocket cs  =   null ;

     private  String ip  =   " localhost " ; //  设置成服务器IP

     private   int  port  =   8821 ;

     private  String sendMessage  =   " Windwos " ;

     public  ClientTest()  {
         try   {
             if  (createConnection())  {
                sendMessage();
                getMessage();
            }

        }   catch  (Exception ex)  {
            ex.printStackTrace();
        }
    }

     private   boolean  createConnection()  {
        cs  =   new  ClientSocket(ip, port);
         try   {
            cs.CreateConnection();
            System.out.print( " 连接服务器成功! "   +   " /n " );
             return   true ;
        }   catch  (Exception e)  {
            System.out.print( " 连接服务器失败! "   +   " /n " );
             return   false ;
        }

    }

     private   void  sendMessage()  {
         if  (cs  ==   null )
             return ;
         try   {
            cs.sendMessage(sendMessage);
        }   catch  (Exception e)  {
            System.out.print( " 发送消息失败! "   +   " /n " );
        }
    }

     private   void  getMessage()  {
         if  (cs  ==   null )
             return ;
        DataInputStream inputStream  =   null ;
         try   {
            inputStream  =  cs.getMessageStream();
        }   catch  (Exception e)  {
            System.out.print( " 接收消息缓存错误/n " );
             return ;
        }

         try   {
             // 本地保存路径，文件名会自动从服务器端继承而来。
            String savePath  =   " E:// " ;
             int  bufferSize  =   8192 ;
             byte [] buf  =   new   byte [bufferSize];
             int  passedlen  =   0 ;
             long  len = 0 ;
            
            savePath  +=  inputStream.readUTF();
            DataOutputStream fileOut  =   new  DataOutputStream( new  BufferedOutputStream( new  BufferedOutputStream( new  FileOutputStream(savePath))));
            len  =  inputStream.readLong();
            
            System.out.println( " 文件的长度为: "   +  len  +   " /n " );
            System.out.println( " 开始接收文件! "   +   " /n " );
                    
             while  ( true )  {
                 int  read  =   0 ;
                 if  (inputStream  !=   null )  {
                    read  =  inputStream.read(buf);
                }
                passedlen  +=  read;
                 if  (read  ==   - 1 )  {
                     break ;
                }
                 // 下面进度条本为图形界面的prograssBar做的，这里如果是打文件，可能会重复打印出一些相同的百分比
                System.out.println( " 文件接收了 "   +   (passedlen  *   100 /  len)  +   " %/n " );
                fileOut.write(buf,  0 , read);
            }
            System.out.println( " 接收完成，文件存为 "   +  savePath  +   " /n " );

            fileOut.close();
        }   catch  (Exception e)  {
            System.out.println( " 接收消息错误 "   +   " /n " );
             return ;
        }
    }

     public   static   void  main(String arg[])  {
         new  ClientTest();
    }
}

这就实现了从服务器端向客户端发送文件的过程,当然,反过来,也一样.稍有不同.代码中对跨平台的细节没有实现,有时间或兴趣的朋友可以提供一下.