ftp文件下载from java code

Question

i have this code to download a single file .

    import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import org.apache.commons.net.ftp.FTPClient;
public class NetTest {
public static void main(String[] args){
FTPClient client = new FTPClient( );
OutputStream outStream;
    try {

this is the part of server and passwords .

   client.connect( "servername" );
    client.login("noman123", "pass");
    String remoteFile = "/a.txt";
    outStream = new FileOutputStream( "a.txt" );

simple fill downloading but error on this line

    client.retrieveFile( remoteFile, outStream );
} catch(IOException ioe) {
    System.out.println( "Error communicating with FTP server." );
} finally {
    try {
        client.disconnect( );
    } catch (IOException e) {
        System.out.println( "Problem disconnecting from FTP server" );
    }
}

}
}

and it gives me errors like i hope that u can understand the issue that im facing now

java.net.SocketException: Software caused connection abort: socket write error at java.net.SocketOutputStream.socketWrite0(Native Method) at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109) at java.net.SocketOutputStream.write(SocketOutputStream.java:153) at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221) at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291) at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295) at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141) at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229) at java.io.BufferedWriter.flush(BufferedWriter.java:254) at org.apache.commons.net.ftp.FTP.__send(FTP.java:496) at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:470) at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:547) at org.apache.commons.net.ftp.FTP.port(FTP.java:872) at org.apache.commons.net.ftp.FTPClient. openDataConnection (FTPClient.java:667) at org.apache.commons.net.ftp.FTPClient.retrieveFile(FTPClient.java:1595) at FtpDownloadDemo.main(FtpDownloadDemo.java:25)

Answer 1

关闭防火墙。在此问题中

Answer 2

Make sure you can ping the server and log in manually, but assuming you're ok there, there's two additional things I would do.

1) Per the FTP Client documentation, check that you're really connected

// After connection attempt, you should check the reply code to verify success.
reply = client.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply))
        { // print more complete error }

There's a full example here .

2) It could be since you're trying to get the remote file "/a.txt" you're trying to get to the root directory and your ftp server isn't set up to allow you access. Try just "a.txt" in whichever directory your ftp client is set to dump a user into.

Answer 3

如果位于防火墙后面，则应调用给定示例代码的文档，您应该调用FTPClient的enterLocalPassiveMode方法。

Answer 4

read this article http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7077696

WORK AROUND to solve this problem start program with

-Djava.net.preferIPv4Stack=true