java文件下载

package wan.url.download;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class FileDownLoad{
	public static void main(String[] args) throws Exception {
		String str="http://www.itconcept.com.hk/mp3/d21.mp3";
		DownLoad dl=new DownLoad(str);
		dl.downLoadBinaryFile();
	}
}
class DownLoad {
	private String url;
	public DownLoad(String url){ this.url=url;}
	public void downLoadBinaryFile(){
		try{
			URL myurl=new URL(url);
			HttpURLConnection httpConnect=(HttpURLConnection)myurl.openConnection();
			httpConnect.connect();
			if(httpConnect.getResponseCode()==HttpURLConnection.HTTP_OK){
				InputStream in=httpConnect.getInputStream();
				long size=httpConnect.getContentLengthLong();
				String[] names=myurl.getFile().split("/");
				String name=names[names.length-1];
				File dir=new File("h:/temp"); 
				if(!dir.isDirectory())
					dir.mkdirs();
				File file=new File(dir.getPath()+"/"+name);
				if(file.exists()) {
					System.out.println("File is Exists!!!!");
					return;
				}
				else{
				file.createNewFile();
				OutputStream out=new FileOutputStream(file);
				
				while(file.length()!=size){
					byte[] buf=new byte[1024]; int count=0;
					while((count=in.read(buf))!=-1) 
						out.write(buf, 0, count);
					}
				in.close();
				out.close();}
				System.out.println("Download Success!");
				} else System.out.println("Connecting error");
		}catch(Exception e){
			new RuntimeException("DownLoad failed ,please try again");
		}
	}

}