Question

package experiments; 

import java.io.*;

 import java.net.Socket; 
/** * * @author User */ 

/*THE CLIENT*/ public class UploadManager { 

public static void setup(String address, int port,String path){ 

try( Socket s = new Socket(address,port); OutputStream out = s.getOutputStream(); InputStream in = s.getInputStream(); DataOutputStream dos = new DataOutputStream(out); 
DataInputStream dis = new DataInputStream(in); )

{ 
/** * send file name and size to server */ 
System.out.println("processing file now"); 

File from = new File(path); 

if(from.exists() && from.canRead()){ 

String FILENAME = from.getName(); 

long FILESIZE = from.length();
 // String FILEHASH 

 /** * write all ,2 * to SERVER */ dos.writeLong(FILESIZE); dos.writeUTF(FILENAME);
 //dos.writeUTF(FILEHASH); 
dos.flush(); 

/** * what does SERVER HAS TO SAY? */

 String RESPONSE_FROM_SERVER_1 =dis.readUTF();
 if(RESPONSE_FROM_SERVER_1 . equalsIgnoreCase("SEND")){ 
uploadFresh(from,dos); 
}   
    /** * in case there was an interruption we need * resume from an offset. */ 

        if(RESPONSE_FROM_SERVER_1 . equalsIgnoreCase("RESUME")){

 /** * length already sent */

 System.out.println("resuming upload"); 

String LENGTH_ALREADY_READ =dis.readUTF(); 

long OFF_SET = Long.parseLong(LENGTH_ALREADY_READ); 

/** * get the file name so we know the exact file */ 

String FILE_REAL_NAME = dis.readUTF(); 

resume(FILE_REAL_NAME,OFF_SET,dos);
 } 
}else{ System.out.println("Couldn't read: err"); 

} 

}catch(Exception ex){ 
ex.printStackTrace(); 
}
 }
 /** the resume method **/ 

private static void resume(String FILE_REAL_NAME,long OFF_SET,DataOutputStream to)throws Exception{ 

/** * copy from the stream or disk to server */ 

FileInputStream reader = null; 

try{
 reader = new FileInputStream(new File("c:\\movies\\hallow.mp4",FILE_REAL_NAME)); byte[] size = new byte [8192]; 

int COUNT_BYTES_READ ; reader.skip(OFF_SET);

//skip the length already written

 while( (COUNT_BYTES_READ = reader.read(size)) >0{ 

to.write(size); 
to.flush();
 } 
}finally{ 
if( reader != null ) reader.close();

 to.close(); 

}
 } 

/** and the normal send method which works as expected **/ 

private static void uploadFresh(File from, DataOutputStream to)throws Exception{

 /** * copy from the stream or disk to server */ 
FileInputStream reader = null;
 try{ 
reader = new FileInputStream(from); 
byte[] size = new byte [1024];
 int COUNT_BYTES_READ ; 

while( (COUNT_BYTES_READ = reader.read(size)) >0){

 to.write(size,0,COUNT_BYTES_READ); to.flush(); 
} 
}finally{ 
if( reader != null ) reader.close();

 to.close(); 
}
 } 
}

//服务器

public class UserServer { 
String ip_Adress; 
int Port; 
ServerSocket ss; 
String path;

public UserServer(String ip_Adress,int Port ){
 this.Port =Port; this.ip_Adress = ip_Adress; this. path = path;
 } 

public void startserver() throws IOException{
 FileOutputStream fos =null; 
// String realhash; 
out.println("starting server"); 

this.ss= new ServerSocket(Port);
 out.println("starting server on port"+Port); out.println("waiting for client conection......"); 

Socket visitor = this.ss.accept(); 

out.println("1 User connected to port");

 /** 
* reading file name and size from upload 
*/ 
try( OutputStream ot =visitor.getOutputStream(); InputStream in = visitor.getInputStream(); DataOutputStream dos = new DataOutputStream(ot); DataInputStream dis = new DataInputStream(in); ){ 

System.out.println("processing debug"); 
long FILE_SIZE = dis.readLong();

 System.out.println(FILE_SIZE+"processing"); 

String FILE_NAME = dis.readUTF(); System.out.println(FILE_NAME+"processing");

 //String FILEHASH = dis.readUTF(); // System.out.println(FILEHASH+"processing"); 

File file = new File("c:\\aylo\\"+FILE_NAME); 

/** * what do We Have TO Say? */
 if(file.exists()){ 
long SIZE = file.length(); 
if(SIZE<FILE_SIZE){ 


String RESUME = "RESUME";   

//tell client to resume the upload
 dos.writeUTF(RESUME); 

/*sending the resuming length in*/ string String size = String.valueOf(SIZE);

 dos.writeUTF(size); 
dos.flush();

 fos=new FileOutputStream(file,true);
//append to exisiting file 

byte[] b = new byte [1024]; int COUNT_BYTES_READ ;
 while( (COUNT_BYTES_READ = dis.read(b)) >0){ 
fos.write(b);
 fos.flush();
} 
} 
} else{ 
} 
if(!file.exists()){
 file.getParentFile().mkdirs();
 file.createNewFile();

 String SEND = "SEND";
 dos.writeUTF(SEND);
 dos.flush();
 fos=new FileOutputStream(file); 

byte b[]=new byte[1024];

 int s;
 while((s=dis.read(b))>0){ 
fos.write(b,0,s); fos.flush(); System.out.println(s+"processing"); 
} 

} 
System.out.println("i'm done reading ");



}catch(Exception ex){ 

ex.printStackTrace();

 }finally{
 fos.close(); 
if(this.ss!=null) this.ss.close(); 
} 
}

//主要

public static void main(String []arg){

     UserServer us = new UserServer("localhost", 2089);
     us.startserver();      

    //start client

 UploadManager.setup("localhost", 2089, ("c:\\movies\\hallow.mp4")); 
    }
     }

我已经搜索并搜索了大多数论坛和操作系统，却一无所获。我想做的是学习或弄清楚如何恢复通过java套接字上传时中断的文件。现在，我的代码部分可用，但是我总是认为是由 new FileOutputStream（from，true）; 构造函数引起的中断或空白任何人都可以检查我的方法并帮助指出我的错误，示例代码演示也将很好。谢谢！

Answer 1

请查看有关变量名称的Java约定；我花了相当长的时间才能找到您的问题，而这很大程度上归因于您的代码看起来不熟悉。另外，确实，请检查您的姓名。命名字节缓冲区以传输字节“大小”类似于命名您最喜欢的猫“马”。这会引起混乱。

问题：这样做的地方很多：

   byte[] buffer = new byte[8192];
   int bytesRead = networkIn.read(buffer);
   fileOut.write(buffer);

，这是不正确的。即使实际读取的字节数少于8192字节，“写入”调用也会写入整个8192字节的整个缓冲区。您需要做的是这样：

   byte[] buffer = new byte[8192];
   int bytesRead = networkIn.read(buffer);
   fileOut.write(buffer, 0, bytesRead);

注意：您的代码中可能存在更多错误；上面的内容肯定会引起问题，并且可以解释为什么恢复操作会生成损坏的文件。

在Java Socket中恢复文件上传

1 个答案: