Java套接字缓冲区和字符串

Question

For a homework i try to send a file and some parameter corresponding to this file. So, i send my file and after my string. The problem is my paramater go to my file and not in my variable. I understand the problem, my loop while continue to write in the file as long as he receives something, but i want to stop it and have my parameter outside from my file.

Here my code client:

public static void transfert(InputStream in, OutputStream out) throws IOException{
        PrintWriter printOut;
        byte buf[] = new byte[1024];   
        int n;
        while((n=in.read(buf))!=-1)
            out.write(buf,0,n);


        printOut = new PrintWriter(out);
        printOut.println("add");
        System.out.println("envoie !!!");
        printOut.println("1");
        printOut.println("3");
       // out.write(getBytes("add"),0,0);
        printOut.flush();
    }

and here my server code :

public static void transfert(InputStream in, OutputStream out, boolean closeOnExit) throws IOException
    {        
        byte buf[] = new byte[1024];

        int n;
        while((n=in.read(buf))!=-1)
            out.write(buf,0,n);

        buffIn = new BufferedReader (new InputStreamReader(in));
        String nom_methode = buffIn.readLine();
        String param1 = buffIn.readLine();
        String param2 = buffIn.readLine();
        System.out.println("methode:"+nom_methode+"param1:"+param1+"param2:"+param2);

        if (closeOnExit)
        {
            in.close();
            out.close();
        }     
    }

edit: I still miss something, now i have an error with my thread, i think the problem is from my loop wich read my file in input. Moreover, actually param still go in my file and not in my param... Why the loop dont stop after EOF ?

error:

Exception in thread "Thread-0" java.lang.IndexOutOfBoundsException
    at java.io.FileOutputStream.writeBytes(Native Method)
    at java.io.FileOutputStream.write(FileOutputStream.java:318)
    at serveurthread.AcceptClient.transfert(AcceptClient.java:45)
    at serveurthread.AcceptClient.run(AcceptClient.java:84)
    at java.lang.Thread.run(Thread.java:722)

client:
 public static void transfert(InputStream in, OutputStream out) throws IOException{
        PrintWriter printOut;
        printOut = new PrintWriter(out);
        byte buf[] = new byte[1024];   
        int n;
        while((n=in.read(buf))!=-1)
            out.write(buf,0,n);


        printOut.print('\u0004');
        printOut.flush();
        printOut.println("add");   
        System.out.println("envoie !!!");
        printOut.println("1");
        printOut.println("3");
       // out.write(getBytes("add"),0,0);
        printOut.flush();
    }

server:

public static void transfert(InputStream in, OutputStream out, boolean closeOnExit) throws IOException
    {        
        byte buf[] = new byte[1024];

    int n;
    while((n=in.read(buf))!= (int)'\u0004'){
        out.write(buf,0,n);
    }

    buffIn = new BufferedReader (new InputStreamReader(in));
    String nom_methode = buffIn.readLine();
    String param1 = buffIn.readLine();
    String param2 = buffIn.readLine();
    System.out.println("methode:"+nom_methode+"param1:"+param1+"param2:"+param2);

    if (closeOnExit)
    {
        in.close();
        out.close();
    }     
}

Answer 1

You are going to need some kind of marker in your stream that signifies the end of the file. I suggest '\' which is the EOF character. Basically, write this character after writing the file, then adjust the loop in the server like this:

while((n=in.read(buf))!=(int)'\u0004')
    out.write(buf,0,n);

Now, the server stops reading the file when necessary, then can get around to reading the string.

Also, read returns a count of bytes read, not a char. I would pass one byte at a time through, by declaring bytes instead of byte arrays.