java中Servlet程序下载文件

//得到需要下载的文件

String path = this.getServletContext().getRealPath("/upload/9/1/图片1.png");

File file = new File(path);

//读取服务器本地的文件

FileInputStream in = new FileInputStream(file);

/**

 * 处理URL编码问题

 */

String fileName = file.getName();

//对文件名进行URl编码

fileName = URLEncoder.encode(fileName, "utf-8");

//判断不同浏览器

String userAgent = request.getHeader("user-agent");

String filefix = null;

if(userAgent.contains("Trident")){

//IE

filefix = "filename="+fileName;

}else if(userAgent.contains("Firefox")){

//Firefox

filefix = "filename*="+fileName;

}else{

filefix = "filename="+fileName;

}

//告诉浏览器以下载方式打开资源

response.setHeader("Content-Disposition", "attachment;"+filefix);

//把本地文件发送给浏览器

byte[] buf = new byte[1024];

int len = 0;

while( (len=in.read(buf))!=-1 ){

response.getOutputStream().write(buf, 0, len);

}

//关闭

in.close();