package com.itcsl.web.dpwnload;
import com.itcsl.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("/dpwnloadServlet")
public class dpwnloadServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.获取请求参数
String filename = request.getParameter("filename");
//2.使用字节输入流加载文件进内存
//2.1找到问价按的服务器路径
ServletContext context = this.getServletContext();
String realPath = context.getRealPath("/img/" + filename);
//2.2用字节流关联
FileInputStream file = new FileInputStream(realPath);
//3设置response的响应头
//3.1设置响应头类型
String mimeType = context.getMimeType(filename);
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-age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.输入流的数据写出输出流
ServletOutputStream outputStream = response.getOutputStream();
byte[] bytes = new byte[1024];
int len=0;
while((len=file.read(bytes))!=-1){
outputStream.write(bytes,0,len);
}
file.close();
outputStream.close();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
工具类Utils
package com.itcsl.web.utils;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Base64;
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
Base64.Encoder encoder = Base64.getEncoder();
filename = "=?utf-8?B?" + encoder.encode(filename.getBytes("utf-8")) + "?=";
} else {
// 其它浏览器
filename = URLEncoder.encode(filename, "utf-8");
}
return filename;
}
}
html页面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<a href="/day15/dpwnloadServlet?filename=1.jpg">图片1</a>
<a href="/day15/dpwnloadServlet?filename=二.jpg">图片2</a>
</body>
</html>