Question

所以，我正在创建一个简单的文件传输应用程序。当我运行它时，我收到连接拒绝错误。现在，防火墙没有问题，因为当我试图从我正在关注的书中运行示例代码时，它运行得很好。服务器启动时没有错误。

服务器代码：

public class Server
{
final static int TRANSFER_PORT = 1215;
final static int FILEINFO_PORT = 1216;
static int filesize;
static String filename;

public static void main(String[] args) throws IOException
{
    ServerSocket fileInfoSocket = new ServerSocket(FILEINFO_PORT);
    try
    {
        System.out.println("Server Started");
        Socket s = fileInfoSocket.accept();
        System.out.println("Connected");
        InputStream is = s.getInputStream();
        DataInputStream dis = new DataInputStream(is);
        filesize = dis.readInt();
        filename = dis.readUTF();
        s.close();
    }
    catch(IOException ioe)
    {
        System.out.println(ioe.getMessage());
    }
    System.out.println("File info received.");

    ServerSocket fileTransferSocket = new ServerSocket(TRANSFER_PORT);
    byte[] fileByteArray = new byte[filesize];
    try
    {
        Socket s = fileTransferSocket.accept();
        InputStream is = s.getInputStream();
        BufferedInputStream bis = new BufferedInputStream(is);
        bis.read(fileByteArray, 0, fileByteArray.length);
        s.close();
        FileOutputStream fos = new FileOutputStream(filename);
        BufferedOutputStream bos = new BufferedOutputStream(fos);
        bos.write(fileByteArray);
        bos.flush();
        bos.close();
    }
    catch(IOException ioe)
    {
        System.out.println(ioe.getMessage());
    }
    System.out.println("Transfer complete!");
}

客户代码：

public class Client
{
final static int FILEINFO_PORT = 1216;
final static int TRANSFER_PORT = 1215;
final static String SERVER_ADDR = "localhost";
static int filesize;
static String filename;

public static void main(String[] args) throws IOException
{
    if(args.length != 1)
    {
        System.out.println("Usage: Client filename");
        return;
    }

    File file = new File(args[0]);
    if(!file.isFile())
    {
        System.out.println("File not found!");
        return;
    }
    filesize = (int) file.length();
    filename = file.getName();

    Socket fileInfoSocket = new Socket(SERVER_ADDR, FILEINFO_PORT);
    try
    {
        OutputStream os = fileInfoSocket.getOutputStream();
        DataOutputStream dos = new DataOutputStream(os);
        dos.writeInt(filesize);
        dos.writeUTF(filename);
        dos.close();
    }
    catch(IOException ioe)
    {
        System.out.println(ioe.getMessage());
    }

    Socket fileTransferSocket = new Socket(SERVER_ADDR, TRANSFER_PORT);
    try
    {
        OutputStream os = fileTransferSocket.getOutputStream();
        BufferedOutputStream bos = new BufferedOutputStream(os);
        FileInputStream fis = new FileInputStream(filename);
        byte[] byteArray = new byte[filesize];
        BufferedInputStream bis = new BufferedInputStream(fis);
        bis.read(byteArray, 0, byteArray.length);
        bos.write(byteArray);
        bos.flush();
        bos.close();
    }
    catch(IOException ioe)
    {
        System.out.println(ioe.getMessage());
    }
}

运行客户端时终端出错：

pratyush@SuperComputer:~/JP/NetworkFileTransfer/Server$ java Client "a.png"
Exception in thread "main" java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at     java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
    at     java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at     java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at java.net.Socket.connect(Socket.java:538)
    at java.net.Socket.<init>(Socket.java:434)
    at java.net.Socket.<init>(Socket.java:211)
    at Client.main(Client.java:54)

Answer 1

如果在fileTransferSocket上，或者fileTransferSocket没有时间打开，则无法正确理解抛出异常的行。试着在客户端睡觉：

  Thread.sleep(100);

在：

  Socket fileTransferSocket = new Socket(SERVER_ADDR, TRANSFER_PORT);

获取ConnectionException：文件传输应用程序上的连接被拒绝

1 个答案: