因为将上传的内容放入到数据库中，所以也就不方便给定一个确切的地址让浏览器来下载，希望直接通过数据流的读
取实现文件的下载，这样更加方便一些。下面我们来演示一下文件的下载代码
package oop.hg.ytu.servlet;import java.io.IOException;import java.io.InputStream;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import oop.hu.ytu.dao.DownLoadDomain;public class DownLoad extends HttpServlet { /** * 实现文件的下载 */ private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { DownLoadDomain dao = new DownLoadDomain(); response.setContentType("text/html;charset=UTF-8"); // 设置为下载application/x-download response.setContentType("application/x-download"); String fileName = request.getParameter("fileName"); fileName = new String(fileName.getBytes("ISO-8859-1"),"UTF-8"); String type = dao.getType(fileName); type = "."+type; type = fileName + type; type = URLEncoder.encode(type, "UTF-8"); response.addHeader("Content-Disposition", "attachment;filename=" + type); InputStream in = dao.readBlob(fileName); ServletOutputStream out = response.getOutputStream(); byte[] buff = new byte[1024]; int i = 0; while((i = in.read(buff))>0){ out.write(buff, 0, i); } out.flush(); out.close(); in.close(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}这里主要就是下载的设置的那些头文件，请求头，还有就是下载的文件名如果含有中文，需要进行一下字符集的编码
才能够实现不乱码！
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