How to read and transfer FTP files in Java

1. Requirements

FTP serves as a file server, and the service provider provides remote connection address, connection port, account number, password and other information.
Client connection can be established based on the above information, and then file reading, file uploading and other operations can be performed on the established connection

2. Dependencies

<!-- FTP相关操作的依赖 -->
<dependency>
    <groupId>commons-net</groupId>
    <artifactId>commons-net</artifactId>
    <version>3.9.0</version>
</dependency>
<!-- IO工具类的依赖 -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.11.0</version>
</dependency>
<!-- lombok依赖 -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.26</version>
    <scope>provided</scope>
</dependency>

3. Key source code

3.0 Configuration information

ftp:
  config:
    host: ${env.ftp.config.host:10.1.1.1}
    port: ${env.ftp.config.port:12345}
    username: ${env.ftp.config.username:ftpUsername}
    password: ${env.ftp.config.password:ftpPwd}
    remote-dir-path: ${env.ftp.config.remote-dir-path:/}

/**
 * @author: Vainycos
 * @description ftp配置信息
 * @date: 2023/4/17 15:16
 */
@Data
@Component
@ConfigurationProperties("ftp.config")
public class FtpConfig {
    private String host;
    private int port;
    private String username;
    private String password;
    /** 初始读取根目录，当前默认/ */
    private String remoteDirPath;
}

3.1 Get the client

/**
* 获取ftp客户端
* @return
*/
public FTPClient getFtpClient(){
    try {
        FTPClient ftpClient = new FTPClient();
        ftpClient.connect(ftpConfig.getHost() ,ftpConfig.getPort());
        // 10分钟连接时间
        ftpClient.setConnectTimeout(600000);
        ftpClient.setDefaultTimeout(600000);
        ftpClient.login(ftpConfig.getUsername() ,ftpConfig.getPassword());
        // login后设置传输的模式
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
        // login后设置被动模式
        ftpClient.enterLocalPassiveMode();
        // login后设置编码
        String LOCAL_CHARSET = "GBK";
        // 开启服务器对UTF-8的支持，如果服务器支持就用UTF-8编码，否则就使用本地编码（GBK）.
        if (FTPReply.isPositiveCompletion(ftpClient.sendCommand("OPTS UTF8", "ON"))) {
            LOCAL_CHARSET = "UTF-8";
        }
        ftpClient.setControlEncoding(LOCAL_CHARSET);
        if (!FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
            log.error("未连接到FTP，用户名或密码错误！");
            ftpClient.disconnect();
        } else {
            log.info("FTP连接成功！");
        }
        // 切换从某个根目录下开始扫描
        ftpClient.changeWorkingDirectory(ftpConfig.getRemoteDirPath());
        return ftpClient;
    }catch (IOException e) {
        log.error("ftp建立连接异常->{}", e);
    }
    return null;
}

3.2 Get the ftp file

/**
* 获取对应目录下的第一级目录文件
* @param ftpClient client
* @throws IOException
*/
public void getFtpFirstDirectoryFiles(FTPClient ftpClient) throws IOException {
    log.info("ftpclient当前工作目录->{}", ftpClient.printWorkingDirectory());
    if (ftpClient != null) {
        FTPFile[] files = ftpClient.listFiles();
        for (FTPFile file : files) {
            String fileName = file.getName();
            if (file.isDirectory()){
                // 每次从根目录下查找第一级目录
                String firstDirectory = ftpConfig.getRemoteDirPath() + "/" + fileName;
                ftpClient.changeWorkingDirectory(firstDirectory);
                log.info("当前目录->{}, 开始扫描录音文件", firstDirectory);
                // 切换目录后直接遍历第一级的文件，不递归第二级目录
                dealFile(ftpClient);
                log.info("{}->目录扫描结束", firstDirectory);
            }
        }
    }
}
/**
 * 处理目录下的文件
 * @param ftpClient
 * @throws IOException
 */
public void dealFile(FTPClient ftpClient) throws IOException {
    FTPFile[] files = ftpClient.listFiles();
        for (FTPFile file : files) {
            String fileName = file.getName();
            if (file.isDirectory()) {
                log.info("{}->为目录，跳过", fileName);
                continue;
            }
            String rootWorkingDirectory = ftpClient.printWorkingDirectory();
            log.info("获取到文件->{}, 开始获取ftp文件流, ftpclient工作目录->{}", fileName, ftpClient.printWorkingDirectory());
            // 开始获取ftp文件流
            InputStream inputStream = ftpClient.retrieveFileStream(new String(fileName.getBytes("UTF-8"), FTP.DEFAULT_CONTROL_ENCODING));
            if (inputStream == null){
                log.error("文件不存在->{}", fileName);
                return;
            }
            byte[] data = IOUtils.toByteArray(inputStream);
            inputStream.close();
            // 关键代码，如果不执行该代码，后续的ftpClient操作将会不生效
            ftpClient.completePendingCommand();
            // 省略...获取到了inputStream 文件流进行后续处理
           }
}

3.3 Close the ftp service connection

/**
 * 关闭FTP服务连接
 * @param ftpClient
 */
public void disConnection(FTPClient ftpClient) {
    try{
        if(ftpClient.isConnected()){
            ftpClient.disconnect();
        }
    }catch(IOException e) {
        log.error("ftpClient.disconnect失败->{}", e);
    }
}

The above is the detailed content of How to read and transfer FTP files in Java. For more information, please follow other related articles on the PHP Chinese website!