使用java套接字從服務器到客戶端的文件傳輸。錯誤在服務器端和文件傳輸到客戶端是空的

我有一個客戶端和服務器，其中在客戶端輸入文件名，該文件名將在服務器端檢查預定義的路徑下，如果文件存在，它將被傳輸以類似的預定義路徑向客戶端發送。我有兩個問題：使用java套接字從服務器到客戶端的文件傳輸。錯誤在服務器端和文件傳輸到客戶端是空的

1）在服務器，我無法比較文件在給定的預定義路徑，因爲它顯示FileNotFoundException（沒有這樣的文件/目錄）。

2）即使出現上述例外情況，文件也會被傳輸並且是空的。

這裏是我的客戶端和服務器：

客戶：

import java.io.*; 
import java.net.*; 
import java.util.*; 
public class ft2client 
{ 
public static void main(String srgs[])throws IOException 
{ 
Socket s=null; 
BufferedReader get=null; 
PrintWriter put=null; 
try 
{ 
s=new Socket("127.0.0.1",8085); 
get=new BufferedReader(new InputStreamReader(s.getInputStream())); 
put=new PrintWriter(s.getOutputStream(),true); 
} 
catch(Exception e) 
{ 
System.exit(0); 
} 
        String u,f; 
        System.out.println("Enter the file name to transfer from server:"); 
        DataInputStream dis=new DataInputStream(System.in); 
        f=dis.readLine(); 
        put.println(f); 
        File f1=new File(f); 
        String str = "/home/user/"; 
        FileOutputStream fs=new FileOutputStream(new File(str,f1.toString())); 
        while((u=get.readLine())!=null) 
        { 
         byte jj[]=u.getBytes(); 
         fs.write(jj); 
        } 
        fs.close(); 
        System.out.println("File received"); 
        s.close(); 
       }  
      }

服務器：

import java.io.*; 
import java.net.*; 
import java.util.*; 
    public class ft2server 
      { 
       public static void main(String args[])throws IOException 
       { 
        ServerSocket ss=null; 
        try 
        { 
         ss=new ServerSocket(8085); 
        } 
        catch(IOException e) 
        { 
         System.out.println("couldn't listen"); 
         System.exit(0); 
        } 
        Socket cs=null; 
        try 
        { 
         cs=ss.accept(); 
         System.out.println("Connection established"+cs); 
        } 
        catch(Exception e) 
        { 
         System.out.println("Accept failed"); 
         System.exit(1); 
        } 
        PrintWriter put=new PrintWriter(cs.getOutputStream(),true); 
        BufferedReader st=new BufferedReader(new InputStreamReader(cs.getInputStream())); 
        String s=st.readLine(); 
        String str = "/home/user/Desktop/"; 
        String path = str + s; 
        System.out.println("The requested file is path: "+path); 
        System.out.println("The requested file is : "+s); 
        File f=new File(path); 
        if(f.exists()) 
        { 
         BufferedReader d=new BufferedReader(new FileReader(s)); 
         String line; 
         while((line=d.readLine())!=null) 
         { 
          put.write(line); 
          put.flush(); 
         } 
         d.close(); 
         System.out.println("File transfered"); 
         cs.close(); 
         ss.close(); 
        } 
       } 
      }

來源

2012-09-28 highlander141

見二進制數據您修改了讀者，因爲他們只能夠字符，不工作勢必會損壞它與字節流。而readline意味着讀到行尾，而在二進制文件中（'\ n'）沒有太大意義。
這是爲PrintWriter的文檔

It does not contain methods for writing raw bytes, for which a program should use unencoded byte streams.

你現在想是用字節數組，並把它們寫爲塊這樣的：

import java.io.*; 
import java.net.*; 
import java.util.*; 
    public class ft2server 
     { 

      public static void main(String args[])throws IOException 
      { 
       ServerSocket ss=null; 
       try 
       { 
        ss=new ServerSocket(8085); 
       } 
       catch(IOException e) 
       { 
        System.out.println("couldn't listen"); 
        System.exit(0); 
       } 
       Socket cs=null; 
       try 
       { 
        cs=ss.accept(); 
        System.out.println("Connection established"+cs); 
       } 
       catch(Exception e) 
       { 
        System.out.println("Accept failed"); 
        System.exit(1); 
       } 
       BufferedOutputStream put=new BufferedOutputStream(cs.getOutputStream()); 
       BufferedReader st=new BufferedReader(new InputStreamReader(cs.getInputStream())); 
       String s=st.readLine(); 
       String str = "/home/milind/Desktop/"; 
       String path = str + s; 
       System.out.println("The requested file is path: "+path); 
       System.out.println("The requested file is : "+s); 
       File f=new File(path); 
       if(f.isFile()) 
       { 
        FileInputStream fis=new FileInputStream(f); 


        byte []buf=new byte[1024]; 
        int read; 
        while((read=fis.read(buf,0,1024))!=-1) 
        { 
         put.write(buf,0,read); 
         put.flush(); 
        } 
        //d.close(); 
        System.out.println("File transfered"); 
        cs.close(); 
        ss.close(); 
       } 
      } 
     }

客戶

import java.io.*; 
import java.net.*; 
import java.util.*; 
public class ft2client 
{ 
    public static void main(String srgs[])throws IOException 
    { 
     Socket s=null; 
     BufferedInputStream get=null; 
     PrintWriter put=null; 
     try 
     { 
      s=new Socket("127.0.0.1",8085); 
      get=new BufferedInputStream(s.getInputStream()); 
      put=new PrintWriter(s.getOutputStream(),true); 

      String f; 
      int u; 
      System.out.println("Enter the file name to transfer from server:"); 
      DataInputStream dis=new DataInputStream(System.in); 
      f=dis.readLine(); 
      put.println(f); 
      File f1=new File(f); 
      String str = "/home/milind/"; 
      FileOutputStream fs=new FileOutputStream(new File(str,f1.toString())); 
      byte jj[]=new byte[1024]; 
      while((u=get.read(jj,0,1024))!=-1) 
      { 
       fs.write(jj,0,u); 
      } 
      fs.close(); 
      System.out.println("File received"); 
      s.close(); 
     }catch(Exception e) 
     { 
      e.printStackTrace(); 
      System.exit(0); 
     } 
    }  
}

來源

2012-09-28 11:53:34 Fluvid

沒有什麼事情是肯定的，當你正在處理的插座。

如果在另一端，你正在閱讀像get.readLine();然後線從發送方程序應該有寫成這樣put.writeBytes("any string variable"+"\n")或put.println("some string variable or literal.")

你正在閱讀就像get.readLine()和你正在編寫無論你是從閱讀字節插座直接文件。

這是我的例子，當我需要純文本以字節傳輸時，我如何在套接字上讀取，寫入。

Server { 
... 
soc = echoServer.accept(); 
out = new DataOutputStream(soc.getOutputStream()); 
out.flush(); 
in = new DataInputStream(soc.getInputStream()); 
out.writeBytes("some text in here \n"); 
out.flush(); 

... 
} 


Client{ 

... 

soc = new Socket("10.210.13.121", 62436); 
out = new DataOutputStream(soc.getOutputStream()); 
out.flush(); 
in = new DataInputStream(soc.getInputStream()); 
... 
while(true) 
    if(in.available() > 0) 
     String str = in.readLine(); 
... 
}

來源

2012-09-28 10:36:43 av1987

請使用f.isFile（）而不是f.exisits。這是一個已知的問題。在服務器你誤寫成
BufferedReader d=new BufferedReader(new FileReader(s));
而不是
BufferedReader d=new BufferedReader(new FileReader(f));
固定編碼

import java.io.*; 
import java.net.*; 
import java.util.*; 
    public class ft2server 
     { 
      public static void main(String args[])throws IOException 
      { 
       ServerSocket ss=null; 
       try 
       { 
        ss=new ServerSocket(8085); 
       } 
       catch(IOException e) 
       { 
        System.out.println("couldn't listen"); 
        System.exit(0); 
       } 
       Socket cs=null; 
       try 
       { 
        cs=ss.accept(); 
        System.out.println("Connection established"+cs); 
       } 
       catch(Exception e) 
       { 
        System.out.println("Accept failed"); 
        System.exit(1); 
       } 
       PrintWriter put=new PrintWriter(cs.getOutputStream(),true); 
       BufferedReader st=new BufferedReader(new InputStreamReader(cs.getInputStream())); 
       String s=st.readLine(); 
       String str = "/home/milind/Desktop/"; 
       String path = str + s; 
       System.out.println("The requested file is path: "+path); 
       System.out.println("The requested file is : "+s); 
       File f=new File(path); 
       if(f.isFile()) 
       { 
        BufferedReader d=new BufferedReader(new FileReader(f)); 
        String line; 
        while((line=d.readLine())!=null) 
        { 
         put.write(line); 
         put.flush(); 
        } 
        d.close(); 
        System.out.println("File transfered"); 
        cs.close(); 
        ss.close(); 
       } 
      } 
     }

其他一個

import java.io.*; 
import java.net.*; 
import java.util.*; 
public class ft2client 
{ 
    public static void main(String srgs[])throws IOException 
    { 
     Socket s=null; 
     BufferedReader get=null; 
     PrintWriter put=null; 
     try 
     { 
      s=new Socket("127.0.0.1",8085); 
      get=new BufferedReader(new InputStreamReader(s.getInputStream())); 
      put=new PrintWriter(s.getOutputStream(),true); 

      String u,f; 
      System.out.println("Enter the file name to transfer from server:"); 
      DataInputStream dis=new DataInputStream(System.in); 
      f=dis.readLine(); 
      put.println(f); 
      File f1=new File(f); 
      String str = "/home/milind/"; 
      FileOutputStream fs=new FileOutputStream(new File(str,f1.toString())); 
      while((u=get.readLine())!=null) 
      { 
       System.out.println(u); 
       byte jj[]=u.getBytes(); 
       fs.write(jj); 
      } 
      fs.close(); 
      System.out.println("File received"); 
      s.close(); 
     }catch(Exception e) 
     { 
      e.printStackTrace(); 
      System.exit(0); 
     } 
    }  
}

來源

2012-09-28 10:37:59 Fluvid

嗨，謝謝，但是當我傳輸一個zip文件時，傳輸的文件大小更多，並且當我嘗試打開它時顯示以下錯誤：_存檔：/home/user/herb_2.5.7-Stable-Full_Package.zip 13175984 6008 警告[/home/user/herb_2.5.7-Stable-Full_Package.zip]：571117285額外的字節在開始處或zipfile內（無論如何嘗試處理）錯誤[/home/user/herb_2.5.7-Stable-Full_Package.zip]：找不到中心目錄的開始; zipfile損壞（請檢查您是否已經在適當的BINARY模式下傳輸或創建了zip文件，並且您已編譯解壓縮正確）_ – highlander141

不要使用Readers和Writers除非你知道的內容字符。如果您不這樣做，請使用InputStreams和OutputStreams。在這種情況下一個ZIP文件肯定是二進制的，不是字符數據，讓你通過使用Readers和Writers.

來源

2012-09-28 11:21:01 EJP

使用java套接字從服務器到客戶端的文件傳輸。錯誤在服務器端和文件傳輸到客戶端是空的

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