Java 文件下载案例
2021/12/10 22:20:10
本文主要是介绍Java 文件下载案例,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
前端
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <a href="/项目名/img/1.png">图片1</a> <a href="/项目名/img/1.avi">视频</a> <hr> <a href="/项目名/downloadServlet?filename=1.jpg">图片1</a> <a href="/项目名/downloadServlet?filename=1.avi">视频</a> </body> </html>
后端
import cn.itcast.web.utils.DownLoadUtils; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.FileInputStream; import java.io.IOException; @WebServlet("/downloadServlet") public class DownloadServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.获取请求参数,文件名称 String filename = request.getParameter("filename"); //2.使用字节输入流加载文件进内存 //2.1找到文件服务器路径 ServletContext servletContext = this.getServletContext(); String realPath = servletContext.getRealPath("/img/" + filename); //2.2用字节流关联 FileInputStream fis = new FileInputStream(realPath); //3.设置response的响应头 //3.1设置响应头类型:content-type String mimeType = servletContext.getMimeType(filename);//获取文件的mime类型 response.setHeader("content-type",mimeType); //3.2设置响应头打开方式:content-disposition //解决中文文件名问题 //1.获取user-agent请求头、 String agent = request.getHeader("user-agent"); //2.使用工具类方法编码文件名即可 filename = DownLoadUtils.getFileName(agent, filename); response.setHeader("content-disposition","attachment;filename="+filename); //4.将输入流的数据写出到输出流中 ServletOutputStream sos = response.getOutputStream(); byte[] buff = new byte[1024 * 8]; int len = 0; while((len = fis.read(buff)) != -1){ sos.write(buff,0,len); } fis.close(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
解决下载文件中文名不显示的工具类
import sun.misc.BASE64Encoder; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; public class DownLoadUtils { public static String getFileName(String agent, String filename) throws UnsupportedEncodingException { if (agent.contains("MSIE")) { // IE浏览器 filename = URLEncoder.encode(filename, "utf-8"); filename = filename.replace("+", " "); } else if (agent.contains("Firefox")) { // 火狐浏览器 BASE64Encoder base64Encoder = new BASE64Encoder(); filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?="; } else { // 其它浏览器 filename = URLEncoder.encode(filename, "utf-8"); } return filename; } }
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