【javaweb:servlet】客户端请求服务端进行文件下载的demonstration

淡淡的烟草味﹌ 2022-06-01 00:37 173阅读 0赞

1、服务端DownloadServlet代码

package indi.response.content;
    
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    
    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 DownloadServlet extends HttpServlet {
    
    	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		//1.获取文件名
    		String filename=request.getParameter("filename");
    		//2.告诉客户端将要下载的文件的类型
    		response.setContentType(this.getServletContext().getMimeType(filename));//最重要
    		//3.告诉客户端该文件不是直接解析而是以附件的形式打开（即下载）
    		response.setHeader("Content-Disposition","attachment;filename="+filename);//最重要
    		//4.获取文件的绝对路径
    		String path=this.getServletContext().getRealPath("/download/"+filename);
    		//5.获取输出流
    		ServletOutputStream output = response.getOutputStream();
    		//6.获取输入流
    		InputStream in=new FileInputStream(path);
    		//7.开始输出文件
    		int len=0;
    		byte[] buffer=new byte[1024];
    		while((len=in.read(buffer))>0) {
    			output.write(buffer,0, len);
    		}
    		in.close();
    		output.close();
    	}
    
    	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		doGet(request, response);
    	}
    }

2.客户端html代码

<!DOCTYPE html>
    <html>
    	<head>
    		<meta charset="UTF-8">
    		<title>文件下载页面</title>
    		<style>
    			div{
    				border: 1px solid saddlebrown;
    				margin: auto;
    				text-align: center;
    			}
    		</style>
    	</head>
    	<body>
    		<div>
    			<h1>根据标签下载服务器中指定的文件</h1>
    			<a href="/WEB14_Response/download/a.flv">a.flv</a><br />
    			<a href="/WEB14_Response/download/a.jpg">a.jpg</a><br />
    			<a href="/WEB14_Response/download/a.mp3">a.mp3</a><br />
    			<a href="/WEB14_Response/download/a.mp4">a.mp4</a><br />
    			<a href="/WEB14_Response/download/a.txt">a.txt</a><br />
    			<a href="/WEB14_Response/download/a.zip">a.zip</a><br />
    			<h1>根据服务器端编码的方式指定的文件</h1>
    			<a href="/WEB14_Response/downloadServlet?filename=a.flv">a.flv</a><br />
    			<a href="/WEB14_Response/downloadServlet?filename=a.jpg">a.jpg</a><br />
    			<a href="/WEB14_Response/downloadServlet?filename=a.mp3">a.mp3</a><br />
    			<a href="/WEB14_Response/downloadServlet?filename=a.mp4">a.mp4</a><br />
    			<a href="/WEB14_Response/downloadServlet?filename=a.txt">a.txt</a><br />
    			<a href="/WEB14_Response/downloadServlet?filename=a.zip">a.zip</a><br />
    		</div>
    	</body>
    </html>