java中数据文件的下载

title = java.net.URLDecoder.decode(title, "UTF-8");//前台传值过来的文件路径
String format = title.substring(title.lastIndexOf("\\") + 1);//文件名称及后缀
String suffix=title.substring(title.lastIndexOf("."),title.length());//文件后缀
String filename=format.substring(0,format.lastIndexOf("."));//文件名
response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(filename + suffix, "UTF-8"));
String realpath=title.replaceAll("\\\\", "\\\\\\\\");
InputStream instream = null;
instream = new FileInputStream(realpath);  ;
//创建输出流
OutputStream out = response.getOutputStream();
//创建缓冲区
byte buffer[] = new byte[1024];
int len = 0;
//循环将输入流中的内容读取到缓冲区当中
while ((len = instream.read(buffer)) > 0) {
//输出缓冲区的内容到浏览器，实现文件下载
out.write(buffer, 0, len);
}
//关闭文件输入流
instream.close();
//关闭输出流
out.close();