java使用apache commons连接ftp修改ftp文件名失败原因

今天被ftp上中文名修改坑了好久

项目用的是 apache commons 里的 FtpClient 实现的对ftp文件的上传下载操作，今天增加了业务要修改ftp上的文件名，然后就一直的报错，问题是它修改名字的方法只返回一个boolean，没有异常，这就很蛋疼了，找了好久才发现是中文的名字的原因

改名

直接上代码

package net.codejava.ftp;
import java.io.IOException;
import org.apache.commons.net.ftp.FTPClient;
public class FTPRenamer {
  public static void main(String[] args) {
    String server = "www.ftpserver.com";
    int port = 21;
    String user = "username";
    String pass = "password";
    FTPClient ftpClient = new FTPClient();
    try {
      ftpClient.connect(server, port);
      ftpClient.login(user, pass);
      // renaming directory
      String oldDir = "/photo";
      String newDir = "/photo_2012";
      boolean success = ftpClient.rename(oldDir, newDir);
      if (success) {
 System.out.println(oldDir + " was successfully renamed to: "
     + newDir);
      } else {
 System.out.println("Failed to rename: " + oldDir);
      }
      // renaming file
      String oldFile = "/work/error.png";
      String newFile = "/work/screenshot.png";
      success = ftpClient.rename(oldFile, newFile);
      if (success) {
 System.out.println(oldFile + " was successfully renamed to: "
     + newFile);
      } else {
 System.out.println("Failed to rename: " + oldFile);
      }
      ftpClient.logout();
      ftpClient.disconnect();
    } catch (IOException ex) {
      ex.printStackTrace();
    } finally {
      if (ftpClient.isConnected()) {
 try {
   ftpClient.logout();
   ftpClient.disconnect();
 } catch (IOException ex) {
   ex.printStackTrace();
 }
      }
    }
  }
}
如果修改的名字里没有中文，用上面的代码就够了，但如果有中文就要对文件名进行转码了，转码代码如下
// renaming file
String oldFile = "/work/你好.png";
String newFile = "/work/世界.png";
success = ftpClient.rename(
  new String(oldFile.getBytes(StandardCharsets.UTF_8), StandardCharsets.ISO_8859_1),
  new String(newFile.getBytes(StandardCharsets.UTF_8), StandardCharsets.ISO_8859_1)
);

这样再修改名字就没有问题了

顺便记录一下上传、下载、删除、检查文件是否存在，同样的，如果有中文名，最好先转一下码再进行操作

上传

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;

public class FTPUploadFileDemo {
  public static void main(String[] args) {
    String server = "www.myserver.com";
    int port = 21;
    String user = "user";
    String pass = "pass";
    FTPClient ftpClient = new FTPClient();
    try {
      ftpClient.connect(server, port);
      ftpClient.login(user, pass);
      ftpClient.enterLocalPassiveMode();
      ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
      // APPROACH #1: uploads first file using an InputStream
      File firstLocalFile = new File("D:/Test/Projects.zip");
      String firstRemoteFile = "Projects.zip";
      InputStream inputStream = new FileInputStream(firstLocalFile);
      System.out.println("Start uploading first file");
      boolean done = ftpClient.storeFile(firstRemoteFile, inputStream);
      inputStream.close();
      if (done) {
 System.out.println("The first file is uploaded successfully.");
      }
      // APPROACH #2: uploads second file using an OutputStream
      File secondLocalFile = new File("E:/Test/Report.doc");
      String secondRemoteFile = "test/Report.doc";
      inputStream = new FileInputStream(secondLocalFile);
      System.out.println("Start uploading second file");
      OutputStream outputStream = ftpClient.storeFileStream(secondRemoteFile);
      byte[] bytesIn = new byte[4096];
      int read = 0;
      while ((read = inputStream.read(bytesIn)) != -1) {
 outputStream.write(bytesIn, 0, read);
      }
      inputStream.close();
      outputStream.close();
      boolean completed = ftpClient.completePendingCommand();
      if (completed) {
 System.out.println("The second file is uploaded successfully.");
      }
    } catch (IOException ex) {
      System.out.println("Error: " + ex.getMessage());
      ex.printStackTrace();
    } finally {
      try {
 if (ftpClient.isConnected()) {
   ftpClient.logout();
   ftpClient.disconnect();
 }
      } catch (IOException ex) {
 ex.printStackTrace();
      }
    }
  }
}

下载

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;

public class FTPDownloadFileDemo {
  public static void main(String[] args) {
    String server = "www.myserver.com";
    int port = 21;
    String user = "user";
    String pass = "pass";
    FTPClient ftpClient = new FTPClient();
    try {
      ftpClient.connect(server, port);
      ftpClient.login(user, pass);
      ftpClient.enterLocalPassiveMode();
      ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
      // APPROACH #1: using retrieveFile(String, OutputStream)
      String remoteFile1 = "/test/video.mp4";
      File downloadFile1 = new File("D:/Downloads/video.mp4");
      OutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(downloadFile1));
      boolean success = ftpClient.retrieveFile(remoteFile1, outputStream1);
      outputStream1.close();
      if (success) {
 System.out.println("File #1 has been downloaded successfully.");
      }
      // APPROACH #2: using InputStream retrieveFileStream(String)
      String remoteFile2 = "/test/song.mp3";
      File downloadFile2 = new File("D:/Downloads/song.mp3");
      OutputStream outputStream2 = new BufferedOutputStream(new FileOutputStream(downloadFile2));
      InputStream inputStream = ftpClient.retrieveFileStream(remoteFile2);
      byte[] bytesArray = new byte[4096];
      int bytesRead = -1;
      while ((bytesRead = inputStream.read(bytesArray)) != -1) {
 outputStream2.write(bytesArray, 0, bytesRead);
      }
      success = ftpClient.completePendingCommand();
      if (success) {
 System.out.println("File #2 has been downloaded successfully.");
      }
      outputStream2.close();
      inputStream.close();
    } catch (IOException ex) {
      System.out.println("Error: " + ex.getMessage());
      ex.printStackTrace();
    } finally {
      try {
 if (ftpClient.isConnected()) {
   ftpClient.logout();
   ftpClient.disconnect();
 }
      } catch (IOException ex) {
 ex.printStackTrace();
      }
    }
  }
}

删除

import java.io.IOException;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
public class FTPDeleteFileDemo {
  public static void main(String[] args) {
    String server = "www.myserver.com";
    int port = 21;
    String user = "user";
    String pass = "pass";
    FTPClient ftpClient = new FTPClient();
    try {
      ftpClient.connect(server, port);
      int replyCode = ftpClient.getReplyCode();
      if (!FTPReply.isPositiveCompletion(replyCode)) {
 System.out.println("Connect failed");
 return;
      }
      boolean success = ftpClient.login(user, pass);
      if (!success) {
 System.out.println("Could not login to the server");
 return;
      }
      String fileToDelete = "/repository/video/cool.mp4";
      boolean deleted = ftpClient.deleteFile(fileToDelete);
      if (deleted) {
 System.out.println("The file was deleted successfully.");
      } else {
 System.out.println("Could not delete the file, it may not exist.");
      }
    } catch (IOException ex) {
      System.out.println("Oh no, there was an error: " + ex.getMessage());
      ex.printStackTrace();
    } finally {
      // logs out and disconnects from server
      try {
 if (ftpClient.isConnected()) {
   ftpClient.logout();
   ftpClient.disconnect();
 }
      } catch (IOException ex) {
 ex.printStackTrace();
      }
    }
  }
}

检查文件/文件夹是否存在

package net.codejava.ftp;
import java.io.IOException;
import java.io.InputStream;
import java.net.SocketException;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;

public class FTPCheckFileExists {
  private FTPClient ftpClient;
  private int returnCode;
  
  boolean checkDirectoryExists(String dirPath) throws IOException {
    ftpClient.changeWorkingDirectory(dirPath);
    returnCode = ftpClient.getReplyCode();
    if (returnCode == 550) {
      return false;
    }
    return true;
  }
  
  boolean checkFileExists(String filePath) throws IOException {
    InputStream inputStream = ftpClient.retrieveFileStream(filePath);
    returnCode = ftpClient.getReplyCode();
    if (inputStream == null || returnCode == 550) {
      return false;
    }
    return true;
  }
  
  void connect(String hostname, int port, String username, String password)
      throws SocketException, IOException {
    ftpClient = new FTPClient();
    ftpClient.connect(hostname, port);
    returnCode = ftpClient.getReplyCode();
    if (!FTPReply.isPositiveCompletion(returnCode)) {
      throw new IOException("Could not connect");
    }
    boolean loggedIn = ftpClient.login(username, password);
    if (!loggedIn) {
      throw new IOException("Could not login");
    }
    System.out.println("Connected and logged in.");
  }
  
  void logout() throws IOException {
    if (ftpClient != null && ftpClient.isConnected()) {
      ftpClient.logout();
      ftpClient.disconnect();
      System.out.println("Logged out");
    }
  }
  
  public static void main(String[] args) {
    String hostname = "www.yourserver.com";
    int port = 21;
    String username = "your_user";
    String password = "your_password";
    String dirPath = "Photo";
    String filePath = "Music.mp4";
    FTPCheckFileExists ftpApp = new FTPCheckFileExists();
    try {
      ftpApp.connect(hostname, port, username, password);
      boolean exist = ftpApp.checkDirectoryExists(dirPath);
      System.out.println("Is directory " + dirPath + " exists? " + exist);
      exist = ftpApp.checkFileExists(filePath);
      System.out.println("Is file " + filePath + " exists? " + exist);
    } catch (IOException ex) {
      ex.printStackTrace();
    } finally {
      try {
 ftpApp.logout();
      } catch (IOException ex) {
 ex.printStackTrace();
      }
    }
  }
}

参考

https://www.codejava.net/java-se/ftp/how-to-start-ftp-programming-with-java

总结

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java使用apache commons连接ftp修改ftp文件名失败原因

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