用Java的Socket加IO流模擬FTP功能

最近學習java編程是一個實驗讓我困惑了很久就是：

編寫實現類似FTP功能的程序，客戶程序向服務器發送字符串”ls”，服務器返回幾個文件名，客戶程序從中選擇一個文件，服務器將該文件發送給客戶端，客戶程序接受該文件並保存在本地硬盤中。（說明：不要求採用FTP協議實現）
下面把代碼貼出來，可以實現文件傳送，

傳送文件中，服務器端吧文件對象內容寫到byte數組中然後由socket發送

接收端主要也是讀getinputstream然後保存到byte數組中，在寫入到文件中

客戶端程序：

package    conan;
import java.io.*;
import java.net.*;
class FTPClient extends Thread{
  Socket     sl;    
  DataOutputStream dos;
  DataInputStream dis;
  public static void main (String[] args) {
    FTPClient ftpc=new FTPClient();
    ftpc.start();    
}
public    String GetCom()throws Exception{
      System.out.println("請輸入命令: ");
      InputStreamReader is=new InputStreamReader(System.in);
        
      char[] buf=new char[100];    
      int len = is.read(buf);
      String str=new String(buf,0,len).trim();
      return str;
}
public    String GetFileName()throws Exception{//獲得輸入的文件名
      System.out.println("輸入文件名: ");
      InputStreamReader is=new InputStreamReader(System.in);
      char[] buf=new char[100];
      int len2=is.read(buf);
      String str=new String(buf,0,len2).trim();    
      return str;
}
public    void    receiveFile(Socket s) throws Exception    //接收文件
                    {                        
                      sl= s;
                      String filename=GetFileName();
                      dos=new DataOutputStream(sl.getOutputStream());
      dos.writeUTF(filename);
      System.out.println("發送文件名成功");
                      File f=new File(File.separator);//當前根目錄
                      File file =new File(f,"Downloads"+File.separator+filename); //保存到當前目錄得Downloads文件裏面                    
                      sl=new Socket("127.0.0.1",5432);    //創建一個socket對象用來傳送文件            
                      BufferedOutputStream buff=new BufferedOutputStream(new FileOutputStream(file));
                      dis=new DataInputStream(sl.getInputStream());
                      byte[]    line=new     byte[102400];    
                      int mount;
                      System.out.println("開始接收文件");
                      System.out.println("文件傳送中....");
                        while((mount=dis.read(line))!=-1){
                          buff.write(line,0,mount);
                          buff.flush();//刷新    
                          Thread.sleep(50);//設置一個等待時間，有利於接收文件
                        }
                        sl.close();
                        buff.close();
                        System.out.println("finished");
}
public void run(){
  try{
      Socket sc;
      sc=new Socket("localhost",4321);
      dos=new DataOutputStream(sc.getOutputStream());
      dos.writeUTF(GetCom());
      dis=new DataInputStream(sc.getInputStream());
      for(int i=0;i<30;i++){
        System.out.println(dis.readUTF());    
      }
      receiveFile(sc);
    }
    catch(Exception e){
      e.printStackTrace();
    }    
}
}

服務器端程序：

package conan;
import    java.net.*;
import    java.io.*;
class FTPServer extends Thread
{    
  ServerSocket server,server1;
  Socket s;
  DataInputStream dis;
  DataOutputStream dos;
    
  public static void main (String[] args) {
    FTPServer ftps=new FTPServer();
    ftps.start();
}
public    void sendFile(String filename)throws Exception
                    {
                      try{    
                        server1=new ServerSocket(5432);
                        s=server1.accept();
                        File path=new File(File.separator);//當前根目錄
                        File file=new File(path,filename);//創建該文件對象
                        System.out.println("將文件獨到緩衝流中");
                        BufferedInputStream buffile=new BufferedInputStream(new FileInputStream(file));
                        byte[] buf=new byte[102400];//每次發送的塊打大小
                        int mount;
                        dos=new DataOutputStream(s.getOutputStream());
                        System.out.println("開始傳送文件");
                        while((mount=buffile.read(buf))!=-1){//傳送文件，將文件內容以字節形式保存到buf中再發送
                          dos.write(buf,0,mount);
                          Thread.sleep(50);                                
                        }                        
                        System.out.println("文件傳送完畢");
                        server1.close();
                        s.close();//關閉清理工作
                        buffile.close();            
                      }
                      catch(Exception e){
                        e.printStackTrace();
                      }
}
public void run(){
  try{
    server=new ServerSocket(4321);//4321端口用來接接收命令
    System.out.println("Listen at 4321 port");
    while(true)
    {
      s=server.accept();//監聽
      dis=new DataInputStream(s.getInputStream());
      byte [] buf=new byte[100];
      int len=dis.read(buf);
      String str=new String(buf,0,len).trim();
      System.out.println("接收命令成功");
      if(str.startsWith("ls")){
        File localfile=new File(File.separator);
        String[] filelist=localfile.list();
        dos=new DataOutputStream(s.getOutputStream());//輸出文件列表
        dos.writeUTF("-------------------File    List--------------------");
        for(int i=0;i<30;i++){
          dos.writeUTF(filelist[i]);
        }
      }
      dis=new DataInputStream(s.getInputStream());
      String filename_from_client=dis.readUTF().trim();
      System.out.println("接收文件名成功");
      System.out.println("傳送得文件名 ："+filename_from_client);
      sendFile(filename_from_client);
        

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

 

終於把實驗做完了，從中也學到不少socket和io得知識，還真不錯。