자바 파일 다운로드 간이 프로젝트

public class servlet extends HttpServlet{
	private ServletConfig servletConfig;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
	//bianli(req, resp);
	// TODO Auto-generated method stub
//resp.getOutputStream().write("  ".getBytes());
	
//String usernameString=	req.getParameter("username");
//	resp.getOutputStream().write(usernameString.getBytes());
	
	
	bianli(req, resp);
	
	
	
	
	
	
	//	super.doGet(req, resp);
//	int a=0;
//	a++;
//	String method=req.getMethod();
//String aString=servletConfig.getInitParameter("data");	
	//	resp.getOutputStream().write(Integer.toString(a).getBytes());
//resp.getOutputStream().write(aString.getBytes());
	}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
		throws ServletException, IOException {
	// TODO Auto-generated method stub
	doGet(req, resp);
}
	@Override
	public void init(ServletConfig config) throws ServletException {
		// TODO Auto-generated method stub
	//	super.init();
		this.servletConfig=config;
	}
public void bianli(HttpServletRequest req, HttpServletResponse resp){

//File file=new File("D:"+File.separator+"test");
File file=new File("D:");
File[]files=file.listFiles();
/*
try {
	resp.getOutputStream().write(files[1].getName().getBytes());
} catch (IOException e) {
	// TODO Auto-generated catch block
	e.printStackTrace();
}
*/
boolean youmeiyou=false;
String usernameString=	req.getParameter("username");

for (int i = 0; i < files.length; i++) {
	if (files[i].getName().contains(usernameString)) {
		youmeiyou=true;
		InputStream in=null;
		OutputStream outputStream=null;
		int len=0;
		byte[]b=new byte[1024];
		resp.setHeader("content-disposition", "attachment;filename="+files[i].getName());
		try {
			outputStream=resp.getOutputStream();
		} catch (IOException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	try {
		in=new FileInputStream(files[i]);
		while ((len=in.read(b))>0) {
			outputStream.write(b,0,len);
			
		}
		
	} 
	
	catch (FileNotFoundException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	} catch (IOException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}return;
	}
	
/*	if(!files[i].getName().contains(usernameString)){
		try {
			resp.getOutputStream().write("         ".getBytes());
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	*/
}
if (youmeiyou==false) {
	try {
		resp.getOutputStream().write("         ".getBytes());
	} catch (IOException e) {
		// TODO Auto-generated catch block
		e.printStackTrace();
	}
}

}

}