Http方式下载Servlet实现

Http方式下载，Servlet实现

与普通的Servlet处理请求类似，浏览器端输入URL，该URL由tomcat分配给相应的Servlet进行处理，以下为示例代码：

public void service(HttpServletRequest req, HttpServletResponse res) {
    
    File file = new File(fileName);
    if(file.exists()) {
        FileInputStream in = new FileInputStream(file);
        try {
            res.setContentType("application/zip");
            res.setContentLength( (int)file.length() );
            res.setHeader("Content-Disposition", "attachment; filename=\""+fileName+"\"");
            ServletOutputStream out = res.getOutputStream();
            int read = 0;
            byte buf[] = new byte[4096];
            while ((read = in.read(buf, 0, 4096)) != -1)
            {
                out.write(buf, 0, read);
            }
            if (out != null)
            {
                out.close();
            }
            in.close();
            file.delete();
        } catch (IOException e) {
            System.out.println(fileName+" 文件下载出错");
            e.printStackTrace();
        }
    } else {
        System.out.println(fileName+" 文件不存在");
    }
}