FTP 连接超时问题

• 解决

使用工具连接没问题，java代码连接Connection timed out。

须在启动时添加参数 .preferIPv4Stack=true，命令如下：

java .preferIPv4Stack=true -jar XXXXXX.jar

• 问题描述

具体报错如下：

.ConnectException: Connection timed out: connect

at .DualStackPlainSocketImpl.connect0(Native Method)

at .DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)

at .AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)

at .AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

at .AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)

at .PlainSocketImpl.connect(PlainSocketImpl.java:172)

at .SocksSocketImpl.connect(SocksSocketImpl.java:392)

at .Socket.connect(Socket.java:5)

at .Socket.connect(Socket.java:538)

at .Socket.<init>(Socket.java:434)

at .Socket.<init>(Socket.java:211)

• FTP连接代码

@Slf4j
public class FtpUtils {

    private static String LOCAL_CHARSET = "GBK";
    private static String SERVER_CHARSET = "ISO-8859-1";

    /**
     @ IP:  FTP 服务器IP地址
     @PORT:  FTP 服务器端口
     @USERNAME:  FTP 服务器登录名称
     @PASSWORD: FTP 服务器登录密码
     */
    private static FTPClient getFtpClient(String IP, Integer PORT, String USERNAME, String PASSWORD){
        FTPClient ftpClient = null;
        try {
            ftpClient = new FTPClient();
            // 连接FTP服务器
            ftpClient.connect(IP, PORT);
            //ftp端口的打开和关闭
            ftpClient.enterLocalPassiveMode();
            // 登录ftp
            ftpClient.login(USERNAME, PASSWORD);
            ftpClient.setFileType(2);  //设置传输文件类型
            int reply = ftpClient.getReplyCode();
            log.debug("login ftp reply:" + reply);
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftpClient.disconnect();
            }
        }catch (Exception e) {
            log.error("登陆ftp服务器异常：" + e.toString());
            ftpClient = null;
        }
        return ftpClient;
    }


    /**
     @ IP:  FTP 服务器IP地址
     @PORT:  FTP 服务器端口
     @USERNAME:  FTP 服务器登录名称
     @PASSWORD: FTP 服务器登录密码
     @PATH: 要上传至FTP的目标目录
     @Local_Path: 要上传的文件所在路径
     @filename: 要上传的文件名称
     */
    public static boolean send(String IP,Integer PORT,String USERNAME,String PASSWORD,String PATH,String Local_Path,String filename){
        boolean result = false;  
        FileInputStream in = null;
        FTPClient ftpClient = null;
        try {
            //获得ftp客户端对象
            ftpClient = getFtpClient(IP, PORT, USERNAME, PASSWORD);
            if(ftpClient == null){
                throw new RuntimeException("ftp init fail!");
            }

                //获得本地的流
                in = new FileInputStream(Local_Path + File.separator + filename);
                result = ftpClient.storeFile(new String(filename.getBytes(LOCAL_CHARSET),SERVER_CHARSET), in);

                log.info(filename + "上传FTP " + result + "....");
            return result;
        } catch (Exception e) {
            throw new RuntimeException("发送文件异常,path=" + PATH + ",filename=" + filename, e);
        }
        finally{
            closeFtpClient(ftpClient);
            if(in != null){
                try {
                    in.close();
                } catch (IOException e) {
                    log.error("关闭本地目录异常,path=" + Local_Path, e);
                }
            }
        }
    }

    private static void closeFtpClient(FTPClient ftpClient){
        try {
            if (ftpClient != null) {
                ftpClient.disconnect();
            }
        } catch (Exception e) {
            log.error("关闭fTP客户端异常", e);
        }
    }

}