jsp+servlet文件下载

你的名字 2022-06-07 04:11 215阅读 0赞

**要下载的文件a.zip位于file目录下：**

![Center][]

**方式一：**

1、DownServlet

package cn.sz.servlet;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.IOException;
    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;
    
    public class DownServlet extends HttpServlet {
    
    	protected void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		String fileName = request.getParameter("filename");
    		//获取要下载的文件所在目录的路径
    		String dirPath = getServletContext().getRealPath("/file");
    		File dirFile = new File(dirPath);
    		//获取要下载的文件
    		File file = new File(dirFile, fileName);
    
    		if (!file.exists()) {
    			response.getWriter().println("文件" + fileName + "不存在");
    			return;
    		}
    
    		String encode = URLEncoder.encode(fileName, "UTF-8");;//解决中文名称乱码问题
    		//重要参数：设置响应头，控制浏览器下载该文件
    		response.setHeader("content-disposition", "attachment;filename=" + encode);//浏览器保存的文件名
    		//读取要下载的文件，保存到文件输入流
    		FileInputStream fis = new FileInputStream(file);
    		//创建输出流
    		ServletOutputStream out = response.getOutputStream();
    		 //创建缓冲区
    		byte[] buffer = new byte[1024];
    		int len;
    		while ((len = fis.read(buffer)) > 0) {
    			out.write(buffer, 0, len);
    		}
    		 //关闭文件输入流
    		fis.close();
    		 //关闭输出流
    		out.close();
    	}
    
    }

2、web.xml

<servlet>
        <servlet-name>DownServlet</servlet-name>
        <servlet-class>cn.sz.hcq.servlet.DownServlet</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>DownServlet</servlet-name>
        <url-pattern>/DownServlet</url-pattern>
      </servlet-mapping>

3、down.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
    	pageEncoding="utf-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title></title>
    </head>
    <body>
    	<h1>文件下载</h1>
    
    	<form action="DownServlet" method="get">
    		
    		<input type="hidden" name="filename" value="a.txt">
    		<button>点击下载</button>
    	</form>
    </body>
    </html>

结果截图：

![Center 1][]

**方式二:**

直接在浏览器请求或作为超链接或使用JS的location对象请求

直接请求文件的路径：http://localhost:8080/Upload/file/a.zip

[Center]: /images/20220607/7d92efb6aa54455586369d8fe31d878a.png
[Center 1]: /images/20220607/a722a44512c544ff9ad5af041aba838c.png