java:ftp上傳 下載文件

jar包：

<dependency>
		  <groupId>commons-net</groupId>
		  <artifactId>commons-net</artifactId>
		  <version>3.5</version>
		</dependency>

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
 
public class FtpFileUtil {
	
	public static  FTPClient  ftp;
	static String ftpHost = "ftpIP";
	static int ftpPort = ftp端口;//默認21
	static String ftpUserName = "ftp用戶名";
	static String ftpPassword = "ftp密碼";
	
	
    public  static boolean uploadFile(String originFileName, InputStream input,String basePath){
        boolean success = false;
        FTPClient ftp = new FTPClient();
        ftp.setControlEncoding("GBK");
        try {
            int reply;
            ftp.connect(ftpHost, ftpPort);// 連接FTP服務器
            ftp.login(ftpUserName, ftpPassword);// 登錄
            reply = ftp.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftp.disconnect();
                return success;
            }
            ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
            ftp.makeDirectory(basePath);
            ftp.changeWorkingDirectory(basePath);
            ftp.storeFile(originFileName,input);
            input.close();
            ftp.logout();
            success = true;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (ftp.isConnected()) {
                try {
                    ftp.disconnect();
                } catch (IOException ioe) {
                }
            }
        }
        return success;
    }
 
    /**
     * 從ftp中下載文件
     * @param path
     *           ftp文件路徑
     * @param fileName
     *           ftp文件名
     * @return
     */
    public static InputStream downFile(String path, String fileName) {
        FTPClient ftp = new FTPClient();
        try {
            int reply;
            ftp.connect(ftpHost, ftpPort);// 連接FTP服務器
            ftp.login(ftpUserName, ftpPassword);// 登錄
           // ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
            // 說明連接成功
            reply = ftp.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftp.disconnect();
                return null;
            }
            ftp.changeWorkingDirectory(path);// 轉移到FTP服務器目錄
            ftp.setControlEncoding("GBK");
            FTPFile[] fs = ftp.listFiles();
            for (FTPFile ff : fs) {
                // 解決下載文件 中文名字亂碼
                /*String gbk = new String(ff.getName().getBytes("UTF-8"), "GBK");*/
                if (ff.getName().equals(fileName)) {
                    /*String name = new String(ff.getName().getBytes("iso-8859-1"), "UTF-8");*/
                    return ftp.retrieveFileStream(new String(ff.getName().getBytes("gbk"),"iso-8859-1"));
                }
            }
            ftp.logout();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (ftp.isConnected()) {
                try {
                    ftp.disconnect();
                } catch (IOException ioe) {
                }
            }
        }
        return null;
    }
    
    
    
    /**
     * Description: 從FTP服務器下載文件
     * 
     * @param basePath ftp上要下載的文件的路徑
     * 				例如：dailyfile/2020/01/01/data.txt  傳dailyfile/2020/01/01/
     * @param fileName 
     * 				例如：data.txt
     * @param localPath
     * 				例如：D:/
     * @return
     */
    public static boolean downloadFile(String basePath,String fileName, String localPath) {
        boolean result = false;
        FTPClient ftp = new FTPClient();
        try {
            int reply;
            ftp.connect(ftpHost, ftpPort);// 連接FTP服務器
            ftp.login(ftpUserName, ftpPassword);// 登錄
            reply = ftp.getReplyCode();
            if (!FTPReply.isPositiveCompletion(reply)) {
                ftp.disconnect();
                return result;
            }
            ftp.changeWorkingDirectory(basePath);// 轉移到FTP服務器目錄
          //  ftp.retrieveFile();
            FTPFile[] fs = ftp.listFiles();
            for (FTPFile ff : fs) {
                if (ff.getName().equals(fileName)) {
                	InputStream inputStream = ftp.retrieveFileStream(new String(ff.getName().getBytes("gbk"),"iso-8859-1"));
                    File localFile = new File(localPath + "/" + ff.getName());
                    OutputStream is = new FileOutputStream(localFile);
                    byte[] b = new byte[1024];
                    int length;
                    while ((length = inputStream.read(b)) > 0) {
                        is.write(b, 0, length);
                    }
                    //ftp.retrieveFile(ff.getName(), is);
                    is.close();
                }
            }
            ftp.logout();
            result = true;
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (ftp.isConnected()) {
                try {
                    ftp.disconnect();
                } catch (IOException ioe) {
                }
            }
        }
        return result;
    }
    
    
    public static void main(String[] args) {
    	downloadFile("dailyfile/2020/01/01/","data.txt","D:/");
	}
}

注意： changeWorkingDirectory方法第二次執行的時候   是以第一次執行的時候爲基礎的。

         例：第一次ftp.changeWorkingDirectory("dailyfile/"),

               如果要到目錄dailyfile/2019/      就要執行ftp.changeWorkingDirectory("2019/")  而不能

              執行ftp.changeWorkingDirectory("dailyfile/2019/")  

           如果硬要執行 ftp.changeWorkingDirectory("dailyfile/2019/")  則先ftp.changeToParentDirectory();回到父目錄