1 项目结构

2 Tomcat 配置

在response.getOutputStream()实现文件下载，如果是多个文件可以把压缩为一个zip文件
Eclipse 中 Dynamic Web Project 已经不怎么使用，请使用 SpringBoot

3 测试代码

3.1 FileDownloadServlet

package com.xu.utils;import java.io.IOException;
import java.util.Properties;import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;/*** Servlet implementation class FileDownloadServlet*/
@WebServlet(name="download",urlPatterns = {"/FileDownloadServlet", "/download"})
public class FileDownloadServlet extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public FileDownloadServlet() {super();// TODO Auto-generated constructor stub}/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubdoPost(request, response);}/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println(System.getProperties().getProperty("java.version"));System.out.println(System.getProperty("java.vm.specification.version"));System.out.println(System.getProperty("java.vm.specification.vendor"));System.out.println(System.getProperty("java.vm.specification.name"));System.out.println(System.getProperty("java.vm.version"));System.out.println(System.getProperty("java.vm.vendor"));System.out.println(System.getProperty("java.vm.name"));if (request.getParameter("op").equalsIgnoreCase("download")) {FileUtils file=new FileUtils();String[] files= {"E:/1.txt","E:/3.txt","E:/2.txt"};try {file.multFileDownload(response, files, "a.zip");} catch (Exception e) {e.printStackTrace();}}}}

3.2 FileUtils

package com.xu.utils;import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServletResponse;public class FileUtils {/*** 1 多文件下载** @param response     HttpServletResponse* @param files[]      待下载文件* @param downloadfile 下载文件文件名+文件类型(a.zip)* @throws Exception* @date 2019年3月29日11:31:35*/public void multFileDownload(HttpServletResponse response, String[] files, String downloadfile) throws Exception {response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型response.setHeader("Content-Disposition", "attachment;fileName=" + downloadfile);FileInputStream instream = null;try {ZipOutputStream zipstream = new ZipOutputStream(response.getOutputStream());for (String file : files) {if (!new File(file).exists()) {continue;}instream = new FileInputStream(file);ZipEntry entry = new ZipEntry(file);zipstream.putNextEntry(entry);byte[] buffer = new byte[1024];int len = 0;while ((len = instream.read(buffer)) != -1) {zipstream.write(buffer, 0, len);}instream.close();zipstream.closeEntry();zipstream.flush();}zipstream.finish();zipstream.close();} catch (IOException e) {new RuntimeException(e.getMessage());}}/*** 2 多文件下载** @param response     HttpServletResponse* @param files[]      待下载文件* @param downloadfile 下载文件* @param path         待下载文件路径* @param tempfile     待下载临时文件* @throws Exception* @date 2019年3月29日11:31:35*/public void multFileDownload(HttpServletResponse response, String[] files, String path, String downloadfile) throws Exception {response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型response.setHeader("Content-Disposition", "attachment;fileName=" + downloadfile);FileInputStream instream = null;try {ZipOutputStream zipstream = new ZipOutputStream(response.getOutputStream());for (String file : files) {if (!new File(path + file).exists()) {continue;}instream = new FileInputStream(path + file);ZipEntry entry = new ZipEntry(path + file);zipstream.putNextEntry(entry);byte[] buffer = new byte[1024];int len = 0;while ((len = instream.read(buffer)) != -1) {zipstream.write(buffer, 0, len);}instream.close();zipstream.closeEntry();zipstream.flush();}zipstream.finish();zipstream.close();} catch (IOException e) {new RuntimeException(e.getMessage());}}/*** 1 单文件下载** @param response     HttpServletResponse* @param filepath     待下载文件路径* @param downloadfile 下载文件* @date 2019年3月29日11:31:35*/public void singleFileDownload(HttpServletResponse response, String filepath, String downloadfile) {response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型response.setHeader("Content-Disposition", "attachment;fileName=" + downloadfile);ServletOutputStream out;File file = new File(filepath);if (!file.exists()) {new RuntimeException("文件不存在");}try {FileInputStream inputStream = new FileInputStream(file);out = response.getOutputStream();byte[] buffer = new byte[1024];int len = 0;while ((len = inputStream.read(buffer)) != -1) {out.write(buffer, 0, len);}inputStream.close();out.flush();out.close();} catch (IOException e) {new RuntimeException(e.getMessage());}}/*** 2 单文件下载** @param response HttpServletResponse* @param filepath 待下载文件路径* @param filename 下载文件名称* @param filetype 下载文件类型* @date 2019年3月29日11:31:35*/public void singleFileDownload(HttpServletResponse response, String filepath, String filename, String filetype) {response.setContentType("multipart/form-data");//1.设置文件ContentType类型，这样设置，会自动判断下载文件类型response.setHeader("Content-Disposition", "attachment;fileName=" + filename + filetype);ServletOutputStream out;File file = new File(filepath);if (!file.exists()) {new RuntimeException("文件不存在");}try {FileInputStream inputStream = new FileInputStream(file);out = response.getOutputStream();byte[] buffer = new byte[1024];int len = 0;while ((len = inputStream.read(buffer)) != -1) {out.write(buffer, 0, len);}inputStream.close();out.flush();out.close();} catch (IOException e) {new RuntimeException(e.getMessage());}}/*** 1 多文件 压缩成 ZIP** @param files         文件名字* @param path          文件路径* @param loaclfilepath 临时文件全路径* @date 2019年3月29日11:31:35*/public void toZip(String[] files, String path, String loaclfilepath) throws Exception {FileInputStream instream = null;ZipOutputStream zipstream = new ZipOutputStream(new FileOutputStream(new File(loaclfilepath)));for (String file : files) {if (!new File(path + file).exists()) {continue;}instream = new FileInputStream(path + file);ZipEntry entry = new ZipEntry(path + file);zipstream.putNextEntry(entry);byte[] buffer = new byte[1024];while ((instream.read(buffer)) != -1) {zipstream.write(buffer, 0, buffer.length);}zipstream.closeEntry();zipstream.flush();}zipstream.finish();zipstream.close();}/*** 2 多文件 压缩成 ZIP** @param files         文件名字* @param path          文件路径* @param loaclfilepath 压缩文件全路径* @date 2019年3月29日11:31:35*/public void toZip(List<String> files, String path, String loaclfilepath) throws Exception {FileInputStream instream = null;ZipOutputStream zipstream = new ZipOutputStream(new FileOutputStream(new File(loaclfilepath)));for (String file : files) {if (!new File(path + file).exists()) {continue;}instream = new FileInputStream(path + file);ZipEntry entry = new ZipEntry(path + file);zipstream.putNextEntry(entry);byte[] buffer = new byte[1024];while ((instream.read(buffer)) != -1) {zipstream.write(buffer, 0, buffer.length);}zipstream.closeEntry();zipstream.flush();}zipstream.finish();zipstream.close();}}

4 测试结果

18
18
Oracle Corporation
Java Virtual Machine Specification
18+36-2087
Oracle Corporation
OpenJDK 64-Bit Server VM

测试项目文件

http://localhost:9090/DynamicWebProject/download?op=download

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测试 Java HttpServletResponse 多文件下载（ZIP压缩）

1 项目结构

2 Tomcat 配置

3 测试代码

3.1 FileDownloadServlet

3.2 FileUtils

4 测试结果

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