Java FTP 下載文件和文件夾

用apache下的common-net.jar包開發Java FTP下載功能

導入apache-net-2.0.jar到工程中以及其他jar

 import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.SocketException;

import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.log4j.Logger;
/**

采用的是apache commons-net架包中的ftp工具類實現的

@author chiyong
*/
public class FtpCollectionUtil {
private String username;
private String password;
private String ftpHostName;
private int port = 21;
private FTPClient ftpClient = new FTPClient();
private FileOutputStream fos = null;
private Logger logger = Logger.getLogger(FtpCollectionUtil.class);

public FtpCollectionUtil(String username, String password,
String ftpHostName, int port) {
super();
this.username = username;
this.password = password;
this.ftpHostName = ftpHostName;
this.port = port;
}
/**

建立連接b
*/
private void connect() {
try {
logger.debug("開始連接");
// 連接
ftpClient.connect(ftpHostName, port);
int reply = ftpClient.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply)) {
ftpClient.disconnect();
}
// 登錄
ftpClient.login(username, password);
ftpClient.setBufferSize(256);

ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
ftpClient.setControlEncoding("utf8");
logger.debug("登錄成功！");
logger.debug("開始登錄！");
} catch (SocketException e) {
logger.error("", e);
} catch (IOException e) {
logger.error("", e);
}
}
/**

關閉輸入輸出流

@param fos
*/
private void close(FileOutputStream fos) {
try {
if (fos != null) {
fos.close();
}

ftpClient.logout();
logger.info("退出登錄");
ftpClient.disconnect();
logger.info("關閉連接");
} catch (IOException e) {
logger.error("", e);
}
}
/**

下載文件

@param ftpFileName
@param localDir
*/
public void down(String ftpFileName, String localDir) {
connect();
downFileOrDir(ftpFileName, localDir);
close(fos);
}

private void downFileOrDir(String ftpFileName, String localDir) {
try {
File file = new File(ftpFileName);
File temp = new File(localDir);
if (!temp.exists()) {
temp.mkdirs();
}
// 判斷是否是目錄
if (isDir(ftpFileName)) {
String[] names = ftpClient.listNames();
for (int i = 0; i < names.length; i++) {
System.out.println(names[i] + "^^^^^^^^^^^^^^");
if (isDir(names[i])) {
downFileOrDir(ftpFileName + '/' + names[i], localDir

File.separator + names[i]);
ftpClient.changeToParentDirectory();
} else {
File localfile = new File(localDir + File.separator
names[i]);
if (!localfile.exists()) {
fos = new FileOutputStream(localfile);
ftpClient.retrieveFile(names[i], fos);

} else {
logger.debug("開始刪除文件");
file.delete();
logger.debug("文件已經刪除");
fos = new FileOutputStream(localfile);
ftpClient.retrieveFile(ftpFileName, fos);
}
}
}
} else {
File localfile = new File(localDir + File.separator

file.getName());
if (!localfile.exists()) {
fos = new FileOutputStream(localfile);
ftpClient.retrieveFile(ftpFileName, fos);

} else {
logger.debug("開始刪除文件");
file.delete();
logger.debug("文件已經刪除");
fos = new FileOutputStream(localfile);
ftpClient.retrieveFile(ftpFileName, fos);
}
ftpClient.changeToParentDirectory();
}
logger.info("下載成功！");
} catch (SocketException e) {
logger.error("連接失敗！", e);
} catch (IOException e) {
logger.error("下載失敗！", e);
}
}
// 判斷是否是目錄
public boolean isDir(String fileName) {
try {
// 切換目錄，若當前是目錄則返回true,否則返回true。
boolean falg = ftpClient.changeWorkingDirectory(fileName);
return falg;
} catch (Exception e) {
e.printStackTrace();
logger.error("", e);
}
return false;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getFtpHostName() {
return ftpHostName;
}
public void setFtpHostName(String ftpHostName) {
this.ftpHostName = ftpHostName;
}
public int getPort() {
return port;
}
public void setPort(int port) {
this.port = port;
}
public class TestFileUtil {
public static void main(String[] args) {
/**

apache common-net實現的
*/
FtpCollectionUtil ftpUtil = new FtpCollectionUtil("webfocus1",
"webfocus1", "192.168.0.2", 21);

// /home/webfocus1/apache-tomcat-6.0.37/webapps/NEZA_ROOT/要下載的文件夾。
ftpUtil.down(
"/home/webfocus1/apache-tomcat-6.0.37/webapps/NEZA_ROOT/",
"D://a");
}
}
} </pre>