问一下，你是想做ftp上传下载么？
首先你需要安装一个ftp服务端程序，启动起来，然后下载一个ftp客户端程序，测试能不能连接，首先这一块儿需要测试通过。
代码ftp上传下载
2.1 上传代码：
import java.io.File
import java.io.FileInputStream
import org.apache.commons.net.ftp.FTPClient
import org.apache.commons.net.ftp.FTPReply
public class test {
private FTPClient ftp
/**
*
* @param path 上传到ftp服务器哪个路径下
* @param addr 地址
* @param port 端口号
* @param username 用户名
* @param password 密码
* @return
* @throws Exception
*/
private boolean connect(String path,String addr,int port,String username,String password) throws Exception {
boolean result = false
ftp = new FTPClient()
int reply
ftp.connect(addr,port)
ftp.login(username,password)
ftp.setFileType(FTPClient.BINARY_FILE_TYPE)
reply = ftp.getReplyCode()
if (!FTPReply.isPositiveCompletion(reply)) {
ftp.disconnect()
return result
}
ftp.changeWorkingDirectory(path)
result = true
return result
}
/**
*
* @param file 上传的文件或文件夹
* @throws Exception
*/
private void upload(File file) throws Exception{
if(file.isDirectory()){
ftp.makeDirectory(file.getName())
ftp.changeWorkingDirectory(file.getName())
String[] files = file.list()
for (int i = 0i <files.lengthi++) {
File file1 = new File(file.getPath()+"\\"+files[i] )
if(file1.isDirectory()){
upload(file1)
ftp.changeToParentDirectory()
}else{
File file2 = new File(file.getPath()+"\\"+files[i])
FileInputStream input = new FileInputStream(file2)
ftp.storeFile(file2.getName(), input)
input.close()
}
}
}else{
File file2 = new File(file.getPath())
FileInputStream input = new FileInputStream(file2)
ftp.storeFile(file2.getName(), input)
input.close()
}
}
public static void main(String[] args) throws Exception{
test t = new test()
t.connect("", "localhost", 21, "yhh", "yhhazr")
File file = new File("e:\\uploadify")
t.upload(file)
}
}
2.2 下载代码
这里没有用到filter，如果用filter就可以过滤想要的文件。
public class Ftp {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Ftp ftp = new Ftp()
String hostname = "www.strawberry.com"
Integer port = 21
String username = "username"
String password = "password"
String remote = "/c.txt"
String local = "/home/tin/LeonChen/FTP/"
try {
ftp.connect(hostname, port, username, password)
System.out.println("接收状态："+ftp.download(remote, local))
ftp.disconnect()
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace()
}
}
private FTPClient ftpClient = new FTPClient()
/*
* * 连接到FTP服务器
* * @param hostname 主机名
* * @param port 端口
* * @param username 用户名
* * @param password 密码
* * @return 是否连接成功
* * @throws IOException
*/
private boolean connect(String hostname, int port, String username,
String password) throws IOException {
ftpClient.connect(hostname, port)
ftpClient.setControlEncoding("UTF-8")
if (FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
if (ftpClient.login(username, password)) {
return true
}
}
disconnect()
return false
}
/*
* 从FTP服务器上下载文件,支持断点续传，上传百分比汇报
*
* @param remote 远程文件路径
*
* @param local 本地文件路径
*
* @return 上传的状态
*
* @throws IOException
*/
public DownloadStatus download(String remote, String local)
throws IOException {
// 设置被动模式
ftpClient.enterLocalPassiveMode()
// 设置以二进制方式传输
ftpClient.setFileType(FTP.BINARY_FILE_TYPE)
DownloadStatus result
// 检查远程文件是否存在
FTPFile[] files = ftpClient.listFiles(new String(remote
.getBytes("UTF-8"), "iso-8859-1"))
if (files.length != 1) {
System.out.println("远程文件不存在")
return DownloadStatus.Remote_File_Noexist
}
long lRemoteSize = files[0].getSize()
String fildName = files[0].getName()
// 本地存在文件，进行断点下载
File f = new File(local+fildName)
if (f.exists()) {
long localSize = f.length()
if (localSize >= lRemoteSize) {
System.out.println("本地文件大于远程文件，下载中止")
return DownloadStatus.Local_Bigger_Remote
}
// 进行断点续传，并记录状态
FileOutputStream out = new FileOutputStream(f, true)
ftpClient.setRestartOffset(localSize)
InputStream in = ftpClient.retrieveFileStream(new String(remote.getBytes("UTF-8"), "iso-8859-1"))
byte[] bytes = new byte[1024]
long step = lRemoteSize / 100
long process = localSize / step
int c
while ((c = in.read(bytes)) != -1) {
out.write(bytes, 0, c)
localSize += c
long nowProcess = localSize / step
if (nowProcess >process) {
process = nowProcess
if (process % 10 == 0)
System.out.println("下载进度：" + process)
// TODO 更新文件下载进度,值存放在process变量中
}
}
in.close()
out.close()
boolean isDo = ftpClient.completePendingCommand()
if (isDo) {
result = DownloadStatus.Download_From_Break_Success
} else {
result = DownloadStatus.Download_From_Break_Failed
}
} else {
OutputStream out = new FileOutputStream(f)
InputStream in = ftpClient.retrieveFileStream(new String(remote.getBytes("UTF-8"), "iso-8859-1"))
byte[] bytes = new byte[1024]
long step = lRemoteSize / 100
long process = 0
long localSize = 0L
int c
while ((c = in.read(bytes)) != -1) {
out.write(bytes, 0, c)
localSize += c
long nowProcess = localSize / step
if (nowProcess >process) {
process = nowProcess
if (process % 10 == 0)
System.out.println("下载进度：" + process)
// TODO 更新文件下载进度,值存放在process变量中
}
}
in.close()
out.close()
boolean upNewStatus = ftpClient.completePendingCommand()
if (upNewStatus) {
result = DownloadStatus.Download_New_Success
} else {
result = DownloadStatus.Download_New_Failed
}
}
return result
}
private void disconnect() throws IOException {
if (ftpClient.isConnected()) {
ftpClient.disconnect()
}
}
}
http的话就用httpclient
。open后，可以返回一个
InputStream
。这个就是你要读到
文件流
。
原理的话，参考你用浏览器打开这个链接显示的内容。
这个返回的是一个HTML网页，需要你解析出里面的文字（一般来说取body中间的内容就行）
其实对于这种文件一般用FTP来下载的。楼上写的那个不对，哈哈。
需要的话自己最好去查一下，怎么用，我有代码，不过告诉你的话也不太好？
URL
url
=
new
URL("http://你的地址")
URLConnection
connection
=
url.openConnection()
InputStream
is
=
connection.getInputStream()
BufferedReader
br
=
new
BufferedReader(new
InputStreamReader(is,"gb2312"))
下面就是解析这个字符串来，自己来吧
public class FtpClientUtil {FtpClient ftpClientprivate String serverprivate int portprivate String userNameprivate String userPasswordpublic FtpClientUtil(String server,int port,String userName,String userPassword){this.server=serverthis.port=portthis.userName=userNamethis.userPassword=userPassword}/*** 链接到服务器* @return*/public boolean open(){if(ftpClient!=null&&ftpClient.serverIsOpen())return truetry{ftpClient= new FtpClient()ftpClient.openServer(server,port)ftpClient.login(userName, userPassword)ftpClient.binary()return true}catch(Exception e){e.printStackTrace()ftpClient=nullreturn false}}public boolean cd(String dir){boolean f = falsetry {ftpClient.cd(dir)} catch (IOException e) {Logs.error(e.toString())return f}return true}/*** 上传文件到FTP服务器* @param localPathAndFileName 本地文件目录和文件名* @param ftpFileName 上传后的文件名* @param ftpDirectory FTP目录如:/path1/pathb2/,如果目录不存在回自动创建目录* @throws Exception*/public boolean upload(String localDirectoryAndFileName,String ftpFileName,String ftpDirectory)throws Exception {if(!open())return falseFileInputStream is=nullTelnetOutputStream os=nulltry{char ch = ' 'if (ftpDirectory.length() >0)ch = ftpDirectory.charAt(ftpDirectory.length() - 1)for (ch == '/' || ch == '\\'ch = ftpDirectory.charAt(ftpDirectory.length() - 1))ftpDirectory = ftpDirectory.substring(0, ftpDirectory.length() - 1)int slashIndex = ftpDirectory.indexOf(47)int backslashIndex = ftpDirectory.indexOf(92)int index = slashIndexString dirall = ftpDirectoryif (backslashIndex != -1 &&(index == -1 || index >backslashIndex))index = backslashIndexString directory = ""while (index != -1) {if (index >0) {String dir = dirall.substring(0, index)directory = directory + "/" + dirftpClient.sendServer("XMKD " + directory + "\r\n")ftpClient.readServerResponse()}dirall = dirall.substring(index + 1)slashIndex = dirall.indexOf(47)backslashIndex = dirall.indexOf(92)index = slashIndexif (backslashIndex != -1 &&(index == -1 || index >backslashIndex))index = backslashIndex}ftpClient.sendServer("XMKD " + ftpDirectory + "\r\n")ftpClient.readServerResponse()os = ftpClient.put(ftpDirectory + "/"+ ftpFileName)File file_in = new File(localDirectoryAndFileName)is = new FileInputStream(file_in)byte bytes[] = new byte[1024]int iwhile ((i = is.read(bytes)) != -1)os.write(bytes, 0, i)//清理垃圾return true}catch(Exception e){e.printStackTrace()return false}finally{if (is != null)is.close()if (os != null)os.close()}}/*** 从FTP服务器上下载文件并返回下载文件长度* @param ftpDirectoryAndFileName* @param localDirectoryAndFileName* @return* @throws Exception*/public long download(String ftpDirectoryAndFileName,String localDirectoryAndFileName)throws Exception{long result = 0if(!open())return resultTelnetInputStream is = nullFileOutputStream os = nulltry{is = ftpClient.get(ftpDirectoryAndFileName)java.io.File outfile = new java.io.File(localDirectoryAndFileName)os = new FileOutputStream(outfile)byte[] bytes = new byte[1024]int cwhile ((c = is.read(bytes)) != -1){os.write(bytes, 0, c)result = result + c}}catch (Exception e){throw e}finally{if (is != null)is.close()if (os != null)os.close()}return result}/*** 返回FTP目录下的文件列表* @param ftpDirectory* @return*/public List<String>getFileNameList(String ftpDirectory){List<String>list = new ArrayList<String>()if(!open())return listtry{DataInputStream dis = new DataInputStream(ftpClient.nameList(ftpDirectory))String filename = ""while((filename=dis.readLine())!=null){list.add(filename)}} catch (Exception e){e.printStackTrace()}return list}/*** 删除FTP上的文件* @param ftpDirAndFileName*/public boolean deleteFile(String ftpDirAndFileName){if(!open())return falseftpClient.sendServer("DELE "+ftpDirAndFileName+"\r\n")return true}/*** 删除FTP目录* @param ftpDirectory*/public boolean deleteDirectory(String ftpDirectory){if(!open())return falseftpClient.sendServer("XRMD "+ftpDirectory+"\r\n")return true}/*** 关闭链接*/public void close(){try{if(ftpClient!=null&&ftpClient.serverIsOpen())ftpClient.closeServer()}catch(Exception e){}} }望采纳，谢谢。
