Java下载文件

public void downloadFile(){
String filePath = request.getParameter("filepath");
try {
filePath = new String(filePath.getBytes("ISO-8859-1"),"UTF-8");
String rootPath = request.getSession().getServletContext().getRealPath("/");
File file = new File(rootPath+filePath);
String downFileName = file.getName();

InputStream fis = new BufferedInputStream(new FileInputStream(file));
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
// 清空response
response.reset();
// 设置response的Header
response.addHeader("Content-Disposition", "attachment;filename=" + new String(downFileName.getBytes()));
response.addHeader("Content-Length", "" + file.length());
OutputStream toClient = new BufferedOutputStream(response.getOutputStream());
response.setContentType("application/octet-stream");
toClient.write(buffer);
toClient.close();
} catch (Exception e) {
log.errorLog("文件下载失败", e);
}
}