Java使用Apache Commons Net实现FTP功能

maven依赖：

<!-- https://mvnrepository.com/artifact/commons-net/commons-net -->
<dependency>
    <groupId>commons-net</groupId>
    <artifactId>commons-net</artifactId>
    <version>3.6</version>
</dependency>

示例代码：

package com.zifeiy.test.normal;

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

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

public class NormalTest20181224FTPClient {
	
	public static String ftpUrl = "xxx.xxx.xxx.xxx";
	public static String ftpUsername = "ftp_username";
	public static String ftpPassword = "ftp_password";
	
	public static void main(String[] args) {
		FTPClient ftp = new FTPClient();
	    FTPClientConfig config = new FTPClientConfig();
	    ftp.configure(config);
	    try {
	    	int reply;
	        ftp.connect(ftpUrl);
	        System.out.println("Connected to " + ftpUrl + ".");
	        System.out.print(ftp.getReplyString());
	        reply = ftp.getReplyCode();

	        if(!FTPReply.isPositiveCompletion(reply)) {
	          ftp.disconnect();
	          System.err.println("FTP server refused connection.");
	          System.exit(1);
	        }
	        
	        ftp.logout();
		} catch (SocketException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (ftp.isConnected()) {
				try {
					ftp.disconnect();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	    
	}
	
}

参考链接：http://commons.apache.org/proper/commons-net/apidocs/org/apache/commons/net/ftp/FTPClient.html