FTPClient中 retrieveFileStream 的用法

      工作需要使用了org.apache.commons.net.ftp.FTPClient来操作FTP，记录一下心得。

      这个类封装的很完善，使用起来也很简单，只是在使用retrieveFileStream的时候碰到了一点小问题，就是不知道怎么完成传输状态，尝试发送abor指令也不行。在咨询了bianbian和查看了源代码之后看到这一段说明以后解决问题： 

/* 
* You must close the InputStream when you 
* finish reading from it. The InputStream itself will take care of 
* closing the parent data connection socket upon being closed. To 
* finalize the file transfer you must call 
* {@link #completePendingCommand completePendingCommand } and 
* check its return value to verify success. 
*/

代码如下：

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

import java.io.IOException; 
import java.io.InputStream; 
import java.net.SocketException; 

public class TestFTP { 

    public static void main(String[] args) { 
        try { 
            FTPClient ftp = new FTPClient(); 
            // initialize ftp connection 
            String remotefile = "test.xml"; 
            InputStream is = null; 

            is = ftp.retrieveFileStream(remotefile); 

            if (is != null) { 
                is.close(); 
            } 

            if (!ftp.completePendingCommand()) { 
                ftp.logout(); 
                ftp.disconnect(); 
            } 

            // continue 
        } catch (SocketException e) { 
            e.printStackTrace(); 
        } catch (IOException e) { 
            e.printStackTrace(); 
        } 
    } 
}

博文来源：http://blog.sunshow.net/2007/03/ftpclient-retrievefilestream-usage/