请教关于JAVA下载文件的问题，望高手们指教

Question

我要在客户端下载服务器端上的一个文件到客户端，怎么做啊？请高手提供源码和注释，谢谢啊！

Answer 1

package wei;
import java.io.*;
import sun.net.ftp.*;
import sun.net.*;
public class Ftp{
  public FtpClient ftpclient=new FtpClient();
  
public void connect(String host,String name,String password){  
try{

ftpclient.openServer(host);
ftpclient.login(name,password);          }catch(Exception e){
          }
      
}

    public void download(String fileserver,String fileclient){

try{
                    
           ftpclient.binary();
           TelnetInputStream readserver=ftpclient.get(fileserver);
           File file_out=new File(fileclient);
           FileOutputStream writeclient=new FileOutputStream(file_out);
           byte[] bytes=new byte[1024];
           int c;
           while ((c=readserver.read(bytes))!=-1) {
           writeclient.write(bytes,0,c);
           }
          readserver.close();
          writeclient.close();
           } catch (IOException ex) {;}
           
}

public void upload(String fileserver,String fileclient){
  try{
      
      ftpclient.binary();                   
      TelnetOutputStream writeserver=ftpclient.put(fileserver);
      File file_out=new File(fileclient);
      FileInputStream readclient=new FileInputStream(file_out);
      byte[] bytes=new byte[1024];
      int c;
      while ((c=readclient.read(bytes))!=-1) {
      writeserver.write(bytes,0,c);
      }
      writeserver.close();
      readclient.close();
      } catch (IOException ex) {;}
      
}

public void indir(String path){
try{

     ftpclient.cd(path);
}catch(Exception e){
}
}
public void back(){
try{
ftpclient.cdUp();
}catch(Exception eq){
}
}
public void changename(String oldname,String newname){
    try{
    
ftpclient.rename(oldname,newname);
}catch(Exception eee){
}
}

public void closeconnect(){
try{
ftpclient.closeServer();
}catch(Exception eeee){
}
}

/* public static void main(String args[]){
Ftp f=new Ftp();
 f.connect("192.168.1.5","wei","123");
           f.indir("v");
           f.changename("w","q");
           f.download("q/d.txt","qq.txt");
           try{
           
            TelnetInputStream ps=f.ftpclient.list();
            int c;
                    while ((c=ps.read())!=-1) {
                    char b=(char)c;
                    String s=Character.toString(b);
                    System.out.print(s);}
                    ps.close();
                    }catch(Exception ee){
                    }

}*/
}
这个可以下载   ftp的

Answer 2

使用什么协议传输?如果是http,ftp这些是可以使用jdk中的URL直接下载的，如
URL url = new URL("ftp://" + "username" + ":" + "password" + "@"
+ "192.168.0.2" + "/" + "1.txt" + ";type=i");
FtpURLConnection connection = (FtpURLConnection) url.openConnection();
System.out.println(connection.getInputStream());记得关闭掉连接