servlet文件上载

import ?java.io.BufferedInputStream;
import ?java.io.BufferedOutputStream;
import ?java.io.File;
import ?java.io.FileInputStream;
import ?java.io.IOException;

import ?javax.servlet.ServletException;
import ?javax.servlet.ServletOutputStream;
import ?javax.servlet.http.HttpServlet;
import ?javax.servlet.http.HttpServletRequest;
import ?javax.servlet.http.HttpServletResponse;

public ? class ?FileDownload? extends ?HttpServlet?{

?? protected ? void ?service(HttpServletRequest?req,?HttpServletResponse?res)
?????? throws ?ServletException,?IOException?{

???? // ?服务器相对路径
????String?path? = ?req.getParameter( " path " );
???? // ?服务器绝对路径
????path? = ?getServletContext().getRealPath( " / " )? + ?path;

???? // ?检查文件是否存在
????File?obj? = ? new ?File(path);
???? if ?( ! obj.exists())?{
??????res.setContentType( " text/html;charset=GBK " );
??????res.getWriter().print( " 指定文件不存在！ " );
?????? return ;
????}

???? // ?读取文件名：用于设置客户端保存时指定默认文件名
???? int ?index? = ?path.lastIndexOf( " \\ " );? // ?前提：传入的path字符串以“\”表示目录分隔符
????String?fileName? = ?path.substring(index? + ? 1 );

???? // ?写流文件到前端浏览器
????ServletOutputStream?out? = ?res.getOutputStream();
????res.setHeader( " Content-disposition " ,? " attachment;filename= " ? + ?fileName);
????BufferedInputStream?bis? = ? null ;
????BufferedOutputStream?bos? = ? null ;
???? try ?{
??????bis? = ? new ?BufferedInputStream( new ?FileInputStream(path));
??????bos? = ? new ?BufferedOutputStream(out);
?????? byte []?buff? = ? new ? byte [ 2048 ];
?????? int ?bytesRead;
?????? while ?( - 1 ? != ?(bytesRead? = ?bis.read(buff,? 0 ,?buff.length)))?{
????????bos.write(buff,? 0 ,?bytesRead);
??????}
????}? catch ?(IOException?e)?{
?????? throw ?e;
????}? finally ?{
?????? if ?(bis? != ? null )
????????bis.close();
?????? if ?(bos? != ? null )
????????bos.close();
????}
??}

}