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This article mainly explains "Java how to achieve FTP upload and download function", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "Java how to achieve FTP upload and download function" bar!

For JAVA to operate a FTP server, you only need to create a FTPClient, and all operations are encapsulated in FTPClient. JDK comes with FTPClient (sun.net.ftp.FtpClient) or a third-party FTPClient. Generally, apache's FTPClient (org.apache.commons.net.ftp.FTPClient) is used. In this article, the FTPClient,API of apache is more or less the same.

Key dependency: commons-net

Encapsulate common operations (upload and download) into tool classes

Package com.day0322;import org.apache.commons.io.IOUtils;import org.apache.commons.lang3.StringUtils;import org.apache.commons.net.ftp.FTPClient;import org.apache.commons.net.ftp.FTPReply;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream / * FTP tool class * File upload * File download * / public class FTPUtil {private static final Logger log = LoggerFactory.getLogger (FTPUtil.class); / * set buffer size 4m * / private static final int BUFFER_SIZE = 1024 * 1024 * 4; / * Local character Encoding * / private static String LOCAL_CHARSET = "GBK" / * UTF-8 character encoding * * / private static final String CHARSET_UTF8 = "UTF-8"; / * OPTS UTF8 string constant * * / private static final String OPTS_UTF8 = "OPTS UTF8"; / * FTP protocol specifies that the file name is encoded as iso-8859-1 * / private static final String SERVER_CHARSET = "ISO-8859-1" Private static FTPClient ftpClient = null; / * Connect to FTP server * / private static void login (OaFtp oaFtp) {ftpClient = new FTPClient (); try {ftpClient.connect (oaFtp.getIp (), Integer.valueOf (oaFtp.getPort (); ftpClient.login (oaFtp.getName (), oaFtp.getPwd ()); ftpClient.setBufferSize (BUFFER_SIZE) FtpClient.setFileType (FTPClient.BINARY_FILE_TYPE); int reply = ftpClient.getReplyCode (); if (! FTPReply.isPositiveCompletion (reply)) {closeConnect ();}} catch (Exception e) {log.error (", e); throw new RuntimeException (e) }} / * close FTP connection * / private static void closeConnect () {if (ftpClient! = null & & ftpClient.isConnected ()) {try {ftpClient.logout (); ftpClient.disconnect ();} catch (IOException e) {log.error ("", e) } / * FTP server path transcoding * * @ param ftpPath FTP server path * @ return String * / private static String changeEncoding (String ftpPath) {String directory = null Try {if (FTPReply.isPositiveCompletion (ftpClient.sendCommand (OPTS_UTF8, "ON")) {LOCAL_CHARSET = CHARSET_UTF8;} directory = new String (ftpPath.getBytes (LOCAL_CHARSET), SERVER_CHARSET);} catch (Exception e) {log.error (", e);} return directory } / * change the working directory * if not, create the working directory * @ param path * / private static void changeAndMakeWorkingDir (String path) {try {ftpClient.changeWorkingDirectory ("/"); path = path.replaceAll ("\", "/"); String [] path_array = path.split ("/") For (String s: path_array) {boolean b = ftpClient.changeWorkingDirectory (s); if (! b) {ftpClient.makeDirectory (s); ftpClient.changeWorkingDirectory (s);} catch (IOException e) {log.error ("", e) Throw new RuntimeException (e);}} / * * upload * @ param oaFtp * @ param filename * @ param in * @ return * / public static boolean upload (OaFtp oaFtp, String filename, String dirPath, InputStream in) {login (oaFtp); if (! ftpClient.isConnected ()) {return false } boolean isSuccess = false; if (ftpClient! = null) {try {if (FTPReply.isPositiveCompletion (ftpClient.sendCommand (OPTS_UTF8, "ON") {LOCAL_CHARSET = CHARSET_UTF8;} ftpClient.setControlEncoding (LOCAL_CHARSET); String path = changeEncoding (dirPath) ChangeAndMakeWorkingDir (path); isSuccess = ftpClient.storeFile (new String (filename.getBytes (), SERVER_CHARSET), in);} catch (Exception e) {log.error (", e);} finally {closeConnect ();}} return isSuccess Download * @ param oaFtp * @ param filename * @ param dirPath * @ param out * @ return * / public static void download (OaFtp oaFtp, String filename, String dirPath, FileOutputStream out) {/ / log in to login (oaFtp); if (ftpClient! = null) {try {String path = changeEncoding (dirPath) ChangeAndMakeWorkingDir (path); String [] fileNames = ftpClient.listNames (); if (fileNames = = null | | fileNames.length = = 0) {return;} for (String fileName: fileNames) {String ftpName = new String (fileName.getBytes (SERVER_CHARSET), LOCAL_CHARSET) If (StringUtils.equals (ftpName,filename)) {InputStream in = ftpClient.retrieveFileStream (fileName); IOUtils.copy (in,out);} catch (IOException e) {log.error ("", e) } finally {closeConnect ();} Test

1. Upload

two。 download

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