文章首发于：clawhub.club

java使用ftp是没有提供创建多级文件夹的能力的，所以只能自己封装实现：
这里引用了commons-net Maven依赖：

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

创建多级目录

FTP远程进入多层目录文件，如果已存在该目录文件，则不创建，如果无，则循环创建多层目录文件,具体源码：

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/**
     * FTP远程进入多层目录文件，如果已存在该目录文件，则不创建，如果无，则循环创建多层目录文件
     *
     * @param ftpClient the ftp client
     * @param remote    the remote
     * @return the boolean
     * @throws IOException the io exception
     */
    private static void changeAndCreateDirectoryIfInExist(FTPClient ftpClient, String remote) throws IOException {
        //尝试进入文件夹
        if (ftpClient.changeWorkingDirectory(remote)) {
            return;
        }
        //进入文件夹失败，分割远程目录
        String[] paths = remote.split(File.separator);
        //迭代每层目录，尝试进入
        for (String path : paths) {
            //尝试进入文件夹
            if (ftpClient.changeWorkingDirectory(remote)) {
                continue;
            }
            //进入文件夹失败，创建文件夹
            if (ftpClient.makeDirectory(path)) {
                //创建文件夹成功，进入文件夹
                ftpClient.changeWorkingDirectory(path);
            }
        }
    }

也贴上获取FTPClient和上传文件的源码：

获取FTPClient

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    /**
     * The constant ACTIVE.
     */
    private static final String ACTIVE = "active";

/**
     * 获取FTP客户端
     *
     * @param ftpIp       IP
     * @param ftpPort     端口
     * @param ftpMode     模式
     * @param ftpUsername 用户名
     * @param ftpPassword 密码
     * @return the ftp client
     * @throws IOException the io exception
     */
    public static FTPClient getFTPClient(String ftpIp, int ftpPort, String ftpMode, String ftpUsername, String ftpPassword) {
        FTPClient ftpClient = new FTPClient();
        try {
            ftpClient.connect(ftpIp, ftpPort);
            ftpClient.login(ftpUsername, ftpPassword);
            ftpClient.changeWorkingDirectory("/");
            ftpClient.setRemoteVerificationEnabled(false);
            if (ACTIVE.equalsIgnoreCase(ftpMode)) {
                ftpClient.enterLocalActiveMode();
            } else {
                ftpClient.enterLocalPassiveMode();
            }
        } catch (IOException e) {
            throw new RuntimeException("获取FTP客户端出错！", e);
        }
        return ftpClient;
    }

上传文件

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/**
    * The constant BUFFER_SIZE.
    */
   private static final int BUFFER_SIZE = 1024;
/**
    * Upload file string.
    *
    * @param ftpClient      the ftp client
    * @param localPath      the local path
    * @param remotePath     the remote path
    * @param targetFileName the target file name
    * @return the string
    */
   public static String uploadFile(FTPClient ftpClient, Path localPath, String remotePath, String targetFileName) {
       String statusCode;
       InputStream fis = null;
       try {
           fis = new ByteArrayInputStream(Files.readAllBytes(localPath));
           //FTP远程进入多层目录文件，如果已存在该目录文件，则不创建，如果无，则循环创建多层目录文件
           changeAndCreateDirectoryIfInExist(ftpClient, remotePath);
           ftpClient.setBufferSize(BUFFER_SIZE);
           ftpClient.setControlEncoding("UTF-8");
           // 二进制
           ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
           ftpClient.storeFile(targetFileName, fis);
           statusCode = ftpClient.getStatus();
       } catch (IOException e) {
           throw new RuntimeException("FTP客户端出错！", e);
       } finally {
           if (null != fis) {
               ftpClose(ftpClient, fis);
           }
       }
       return statusCode;

   }
 /**
    * Ftp close.
    *
    * @param ftpClient the ftp client
    * @param fis       the fis
    */
   private static void ftpClose(FTPClient ftpClient, InputStream fis) {
       try {
           fis.close();
           if (null != ftpClient && ftpClient.isConnected()) {
               ftpClient.logout();
               ftpClient.disconnect();
           }
       } catch (IOException e) {
           throw new RuntimeException("关闭FTP客户端出错！", e);
       }

   }

如果代码有问题，欢迎评论交流。