使用Java在CentOS ec2实例上进行FTP

Question

FTP从我们的服务器（FileZilla，以被动模式设置）到部署在CentOS ec2实例上的Web应用程序的FTP传输有问题。 从实例wget和FTP手动测试，我们能够进行身份验证，改变目录，并获取文件。 但是，部署了ec2的webapp确实可以进行身份​​验证和导航，但无法获取文件。 应用程序中的FTP上传可以在我们的局域网上正常工作，也可以在外部进行测试（无线网络上的开发笔记本电脑，没有VPN）

作为此过程的一部分，我们编写了更加集中的单元测试，并且目前正在重现使用ec2（失败）和非ec2（成功）部署的失败和成功案例：

import org.junit.Test;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

public class FTPTest {

    @Test
    public void testFTPAccess() throws IOException {
        String fileUrl = "ftp://username:password@ftp.site.com/path/to/resource.txt";
        URL url = new URL(fileUrl);
        URLConnection uc = url.openConnection();
        InputStream is = uc.getInputStream();
        ByteArrayOutputStream out = new ByteArrayOutputStream(1024*10);
        com.google.common.io.ByteStreams.copy(is,out);
        System.out.println(new String(out.toByteArray()));
    }
}

FileZilla服务器日志文件通过登录名，USER，PASS，CWD相同，但是一旦传输开始就不同。

成功案例如下：

(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> Connected, sending welcome message...
(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> 220-FileZilla Server version 0.9.24 beta
(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> 220 Connected to server FTP!
(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> USER ftpUser
(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> 331 Password required for ftpUser
(000216) 8/28/2012 10:47:20 AM - (not logged in) (external IP)> PASS *********
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> 230 Logged on
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> TYPE I
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> 200 Type set to I
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> CWD DPS
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> 250 CWD successful. "/DPS" is current directory.
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> CWD DP276
(000216) 8/28/2012 10:47:20 AM - ftpUser (external IP)> 250 CWD successful. "/DPS/DP276" is current directory.
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> PASV ALL
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> 227 Entering Passive Mode (FTP Server IP4,190)
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> PASV
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> 227 Entering Passive Mode (FTP Server IP4,191)
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> RETR sales.txt
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> 150 Connection accepted
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> 226 Transfer OK
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> QUIT
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> 221 Goodbye
(000216) 8/28/2012 10:47:21 AM - ftpUser (external IP)> disconnected.

失败案例：

(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> Connected, sending welcome message...
(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> 220-FileZilla Server version 0.9.24 beta
(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> 220 Connected to server FTP!
(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> USER ftpUser
(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> 331 Password required for ftpUser
(000217) 8/28/2012 11:25:11 AM - (not logged in) (ec2 Instance IP)> PASS *********
(000217) 8/28/2012 11:25:11 AM - ftpUser (ec2 Instance IP)> 230 Logged on
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> TYPE I
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 200 Type set to I
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> CWD DPS
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 250 CWD successful. "/DPS" is current directory.
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> CWD DP276
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 250 CWD successful. "/DPS/DP276" is current directory.
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> EPSV ALL
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 229 Entering Extended Passive Mode (|||1318|)
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> EPSV
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 229 Entering Extended Passive Mode (|||1319|)
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> EPRT |1|ec2 internal IP|37245|
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 200 Port command successful
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> RETR products.txt
(000217) 8/28/2012 11:25:12 AM - ftpUser (ec2 Instance IP)> 150 Opening data channel for file transfer.
(000217) 8/28/2012 11:25:23 AM - ftpUser (ec2 Instance IP)> 425 Can't open data connection.

Answer 1

尝试在测试方法的末尾调用out.flush（）或out.close（）。 似乎主线程快死了，没有将内容刷新到服务器。

Answer 2

成功案例使用被动模式，而失败案例使用扩展被动模式。 使用普通的URLConnection可能很难调整FTP连接。 我强烈建议改用Java客户端库，例如Apache Commons Net 。 您会在主页上找到一个FTP示例。