How to check whether the specified file exists in ftp server in java

During the project work, it is necessary to check whether the specified file in the ftp server exists. I checked the relevant information on the Internet and can implement it through the ftpClient class.

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Specific implementation code:

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;

/**
*  检验指定路径的文件是否存在ftp服务器中
* @param filePath--指定绝对路径的文件
* @param user--ftp服务器登陆用户名
* @param passward--ftp服务器登陆密码
* @param ip--ftp的IP地址
* @param port--ftp的端口号
* @return
*/

public static boolean isFTPFileExist(String filePath,String user,String passward,String ip,int port){
        FTPClient ftp = new FTPClient();
        try {
　　　　// 连接ftp服务器
            ftp.connect(ip, port);
            // 登陆    
            ftp.login(user, passward);
           // 检验登陆操作的返回码是否正确
            if(!FTPReply.isPositiveCompletion(ftp.getReplyCode())){
                ftp.disconnect();
                return false;
            }
            
            ftp.enterLocalActiveMode();
            // 设置文件类型为二进制，与ASCII有区别
            ftp.setFileType(FTP.BINARY_FILE_TYPE);
            // 设置编码格式
            ftp.setControlEncoding("GBK");
            
            // 提取绝对地址的目录以及文件名
            filePath = filePath.replace("ftp://"+ip+":"+port+"/", "");
            String dir = filePath.substring(0, filePath.lastIndexOf("/"));
            String file = filePath.substring(filePath.lastIndexOf("/")+1);
            
            // 进入文件所在目录，注意编码格式，以能够正确识别中文目录
            ftp.changeWorkingDirectory(new String(dir.getBytes("GBK"),FTP.DEFAULT_CONTROL_ENCODING));

            // 检验文件是否存在
            InputStream is = ftp.retrieveFileStream(new String(file.getBytes("GBK"),FTP.DEFAULT_CONTROL_ENCODING));
            if(is == null || ftp.getReplyCode() == FTPReply.FILE_UNAVAILABLE){
                return false;
            }
            
            if(is != null){
                is.close();
                ftp.completePendingCommand();
            }
            return true;
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(ftp != null){
                try {
                    ftp.disconnect();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return false;
}

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