java - FTP 异常 501 "pathname"超过 8 个字符

Question

我正在尝试使用 FTP 协议(protocol)通过 URI 访问文件。出于明显的安全原因，我必须做出一些更改，但这似乎就是问题的根源。

我的 URI 如下: ftp://user:pasword@host.net/u/Bigpathname/XYZ/ABC/BigPathname/bigpathname/xyz/abc/MY_LOG.LOG

我看到了这个异常:

sun.net.ftp.FtpProtocolException: CWD Bigpathname:501 A qualifier in "Bigpathname" is more than 8 characters

This is really confusing as I can access the file from a Windows 7 command line with the CD command just fine. Both one directory at a time and as a full path.

I found one article mentioning that MVS file names must be 8 or fewer characters but this does not explain how I can get to these same files from my command line! They do exist there is data there that I can download manual but I can not get there via a URI in Java.

PS I use .toURL().openStream() to get files on my local machine just fine, it only fails when I try to get them from my server.

EDIT October 1st

I am able to access files on the MVS host using FileZilla and the basic FTP client from the Windows 7 command line - but I still cannot get them from a URI/URL. I downloaded a very basic Java built FTP client and tried accessing the same file in my program from there and the path works but because my file name has a dot in it "MY_LOG.LOG" I am getting File does not exist 501 Invalid data set name "MY_LOG.LOG". Use MVS Dsname conventions. I am utterly perplexed by this...

EDIT Ocotober 1st afternoon :)

OK I finally got it to work with a FTP client in my Java code - but I still want to use the URL class as I have logs on both local and remote machines. Is there a way to encode a URL string so that it can retrieve a file from a remote machine with the FTP protocol? I am not sure how it works in the Java URL class but in the FTP client I had to use the CWD and then the RETR command.

If I can do this then I have one solution for getting all my logs, otherwise I will have to detect if it is a file or ftp URL and then behave differently. Not the end of the world but not what I want...

The code that tries to get the file with just a URL is as follows: (sysc is a valid host)

void testFTP()
{
   String ftp = "ftp://user:pword@sysc/u/Xxxxxxxxxx/ICS/YT7/XxxxxXxxxxxxx/xxxxxxxxx/logs/xxxxxxxx/XX_YT.LOG";

   try
   {
       URI uri = new URI(ftp);
       URL ftpFile = uri.toURL();

       BufferedReader in = new BufferedReader(new InputStreamReader(ftpFile.openStream()));

       String inputLine;
       while ((inputLine = in.readLine()) != null)
        System.out.println(inputLine);

       in.close();
    }
    catch(Exception e)
    {
       e.printStackTrace();
    }
}

Answer 1

在这种情况下，我认为问题也与服务器相关，对于我来说，Filezilla Server 一切正常，除非文件名长度(包括目录)超过 255 个字符，但如果您想将 URL 类与另一个 FTP 一起使用，则必须重写或实现您自己的 URLStreamHandlerFactory。

       URL.setURLStreamHandlerFactory(...);

我还没有找到任何适合我最喜欢的 java FTP 客户端的 Apache，所以我开发了一个，但可能需要一些修改。

package net.custom.streamhandler.apacheftp;

import java.io.IOException;
import java.io.InputStream;
import java.net.SocketException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;


public class ApacheURLStreamHandlerFactory implements URLStreamHandlerFactory { 
    public URLStreamHandler createURLStreamHandler(String protocol) { 
        //this will only override the chosen protocol  
        if ( protocol.equalsIgnoreCase("ftp") ) 
            return new CustomHandler(); 
        else 
            return null;
    } 
}
class CustomHandler extends URLStreamHandler { 
    protected URLConnection openConnection(URL url) 
       throws IOException { 
        return new CustomURLConnection(url); 
    } 
} 

class CustomURLConnection extends URLConnection { 

    int reply;
    FTPClient ftp = new FTPClient();
    InputStream in;
    static int defaultPort = 21; 
    static String defaultPath = "/"; 

    CustomURLConnection ( URL url) 
        throws IOException { 
        super( url ); 
    } 
    synchronized public void connect() throws IOException {  
            try {
                int port; 
                if ((port = url.getPort()) == -1 ) 
                    port = defaultPort; 

                ftp.connect(url.getHost(), port);
                String login = "anonymous";
                String password = "";
                if(url.getAuthority().indexOf(':')>-1 && 
                        url.getAuthority().indexOf('@')>-1){
                            String []auxArray = url.getAuthority().replaceAll("@", ":").split(":");
                            login = auxArray[0];
                            password = auxArray[1];
                }               

                ftp.login(login, password);             

                reply = ftp.getReplyCode();
                if (FTPReply.isPositiveCompletion(reply)) {
                    System.out.println("Connected Apache Success");
                } else {
                    System.out.println("Connection Apache Failed");
                    ftp.disconnect();
                }
                in = ftp.retrieveFileStream(url.getFile());

            } catch (SocketException ex) {
                ex.printStackTrace();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        connected = true;        

    } 
    synchronized public InputStream getInputStream() 
       throws IOException { 
        if (!connected) 
            connect(); 
        return ( in );  
    }  
} 

*请记住，您可以通过这种方式实现新的方法来处理 java.net.URL 的不同协议(protocol)。

你的代码...

    ...
{
   String ftp = "ftp://user:pword@sysc/u/Xxxxxxxxxx/ICS/YT7/XxxxxXxxxxxxx/xxxxxxxxx/logs/xxxxxxxx/XX_YT.LOG";    
   try
   {
       URL.setURLStreamHandlerFactory(new ApacheURLStreamHandlerFactory()); 
    ...

再见

**(犯错是人之常情，宽恕是神圣的)