java从ftp上下载图片到客户端本地

最新推荐文章于 2025-10-22 15:30:36 发布

原创最新推荐文章于 2025-10-22 15:30:36 发布 · 9k 阅读

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文章标签：

#java #web #ftp #服务器 #客户端

这篇博客主要介绍了如何使用Java从FTP服务器下载图片，并将其保存到客户端本地的详细步骤，结合Servlet实现文件的传输。

本例子以servlet为主。

下面是大概思路

public class FtpServlet extends HttpServlet{

@Override

protected void doGet(HttpServletRequest request , HttpServletResponse response )

throws IOException, ServletException {

response .setContentType( "text/html" );

String remotePath = request .getParameter( "remotePath" );//ftp路径

String fileName = request .getParameter( "fileName" );//ftp上的文件名称

String ios =System.getProperty( "os.name" ).toLowerCase();//获取系统名称，根据不同系统创建不同的存储路径

String path = "" ;

if ( ios .indexOf( "windows" )>=0){

path =Configs.get( "CommonFile.upfile_windows" );

} else {

path =Configs.get( "CommonFile.upfile_linux" );

}

File mk = new File( path );

//如果文件夹不存在则创建

if (! mk .exists() && ! mk .isDirectory())

{

mk .mkdir();

}

//远程连接ftp并下载图片到服务器

FtpUtil.downFile( "10.24.10.36" , 21, "fy4" , "fy4" , remotePath , fileName , path );

//读取文件

File file = new File( path + fileName );

try {

FileInputStream is ;

is = new FileInputStream( file );

ServletOutputStream os = response .getOutputStream();

BufferedOutputStream bos = new BufferedOutputStream( os );

response .setHeader( "Content-Disposition" , "attachment; filename=\"" + fileName + "\"" );

byte [] len = new byte [1024*2];

int read = 0;

while (( read = is .read( len )) != -1){

bos .write( len , 0, read );

System. out .println( "read---" + read );

}

bos .flush();

bos .close();

is .close();

} catch (Exception e ) {

e .printStackTrace();

}

public class FtpUtil {

/**

* Description: 从FTP服务器下载文件

* @param url

* FTP服务器hostname

* @param port

* FTP服务器端口

* @param username

* FTP登录账号

* @param password

* FTP登录密码

* @param remotePath

* FTP服务器上的相对路径

* @param fileName

* 要下载的文件名

* @param localPath

* 下载后保存到服务器的路径

* @return

public static boolean downFile(String url , int port , String username ,

String password , String remotePath , String fileName ,String path

) {

boolean success = false ;

FTPClient ftp = new FTPClient();

int reply ;

try {

ftp .connect( url , port );

ftp .login( username , password );

ftp .setFileType(FTPClient. BINARY_FILE_TYPE ); //文件类型为二进制文件

reply = ftp .getReplyCode();

if (!FTPReply.isPositiveCompletion( reply )) {

ftp .disconnect();

return success ;

}

ftp .enterLocalPassiveMode(); //本地模式

ftp .changeWorkingDirectory( remotePath );

FTPFile[] fs = ftp .listFiles();

for (FTPFile ff : fs ) {

if ( ff .getName().equals( fileName )) {

File localFile = new File( path + ff .getName());

OutputStream is = new FileOutputStream( localFile );

ftp .retrieveFile( ff .getName(), is );

is .close();

}

ftp .logout();

success = true ;

} catch (SocketException e ) {

// TODO Auto-generated catch block

e .printStackTrace();

} catch (IOException e ) {

// TODO Auto-generated catch block

e .printStackTrace();

} finally {

if ( ftp .isConnected()) {

try {

ftp .disconnect();

} catch (IOException e ) {

// TODO Auto-generated catch block

e .printStackTrace();

}

return success ;

}

前台访问配置的servlet路径即可在网页上实现下载功能