webapp項目的結構如下圖：
download.html文件的內容如下：
<!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body> <h1>資源下載:</h1> <p> 單純地使用a標籤時，只有瀏覽器不能解析的文件才會是下載，否則將被瀏覽器直接解析。 </p> <a href="/WEB/resource/a.mp3" rel="external nofollow" >a.mp3</a><br> <a href="/WEB/resource/a.exe" rel="external nofollow" >a.exe</a><br> <a href="/WEB/resource/a.txt" rel="external nofollow" >a.txt</a><br> <a href="/WEB/resource/a.xlsx" rel="external nofollow" >a.xlsx</a><br> <a href="/WEB/resource/a.png" rel="external nofollow" >a.png</a><br> <p>因此，使用a標籤結合servlet的response指示瀏覽器不解析這些待下載文件</p> <a href="/WEB/download?filename=a.mp3" rel="external nofollow" >a.mp3</a><br> <a href="/WEB/download?filename=a.exe" rel="external nofollow" >a.exe</a><br> <a href="/WEB/download?filename=a.txt" rel="external nofollow" >a.txt</a><br> <a href="/WEB/download?filename=a.xlsx" rel="external nofollow" >a.xlsx</a><br> <a href="/WEB/download?filename=a.png" rel="external nofollow" >a.png</a><br></body></html>
負責處理下載的Servlet――download.java文件的內容如下：
package com.download.servlet;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;/** * Servlet implementation class Download */public class Download extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.獲取請求下載的文件名String filename = request.getParameter("filename"); //2.獲取文件的文件系統路徑String filePath = request.getServletContext().getRealPath("resource/"+filename); //3.設置響應頭，提示瀏覽器不要解析響應的文件數據，而是以附件(attachment)的形式解析，即下載功能response.setContentType(this.getServletContext().getMimeType(filename)); response.setHeader("Content-Disposition", "attachment;filename="+filename); //4.讀取文件的輸入流，以及響應的輸出流，並將數據輸出給客戶端InputStream in = new FileInputStream(filePath); ServletOutputStream out = response.getOutputStream(); int len = 0; byte[] buf = new byte[1024]; while((len=in.read(buf))!=-1) { out.write(buf, 0, len); } in.close(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); }}在瀏覽器地址欄中輸入http://localhost:8080/DownloadServlet/download.html。
以上這篇java web response提供文件下載功能的實例講解就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持武林網。