<dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>4.0.1</version><scope>provided</scope></dependency>

<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.java</groupId><artifactId>upload</artifactId><version>1.0.0</version><packaging>war</packaging><dependencies><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.4</version></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>4.0.1</version><scope>provided</scope></dependency></dependencies><build><finalName>${project.artifactId}</finalName><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>1.8</source><target>1.8</target><encoding>UTF-8</encoding></configuration></plugin></plugins></build>
</project>

package com.java.servlet;import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FileUtils;/*** 原生Servlet上传文件* */
public class UploadFileServlet extends HttpServlet {private static final long serialVersionUID = -755404037178760784L;/*** 设置字符集为UTF-8*/private static final String ENCODING = "UTF-8";@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {if (ServletFileUpload.isMultipartContent(request)) {try {DiskFileItemFactory factory = new DiskFileItemFactory();ServletFileUpload upload = new ServletFileUpload(factory);List<FileItem> items = upload.parseRequest(request);// 存储普通表单参数Map<String, String> paramMap = new HashMap<>();// 存储文件参数Map<String, FileItem> fileMap = new HashMap<>();/* 解析表单参数 */for (FileItem item : items) {// 普通表单参数if (item.isFormField()) {paramMap.put(item.getFieldName(), item.getString(ENCODING));}// 文件参数else {fileMap.put(item.getFieldName(), item);}}/* 从参数集合中获取需要的参数 */String uploadPath = paramMap.get("uploadPath");FileItem fileItem = fileMap.get("file");String fileName = fileItem.getName();File outFile = new File(uploadPath, fileName);if (outFile.exists()) {FileUtils.forceDelete(outFile);}fileItem.write(outFile);write(response, "上传完成:" + outFile.getAbsolutePath());} catch (FileUploadException e) {e.printStackTrace();write(response, e.getMessage());} catch (Exception e) {e.printStackTrace();write(response, e.getMessage());}}// 请求Content-type设置错误时给出提示else {write(response, "非multipart类型，检查Content-type");}}private void write(HttpServletResponse response, String message) {response.setContentType("text/html; charset=UTF-8");PrintWriter writer = null;try {writer = response.getWriter();writer.write(message);writer.flush();} catch (IOException e) {e.printStackTrace();} finally {writer.close();}}}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns="http://java.sun.com/xml/ns/javaee"xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"version="2.5"><display-name>upload</display-name><welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list><servlet><servlet-name>uploadFile</servlet-name><servlet-class>com.java.servlet.UploadFileServlet</servlet-class></servlet><servlet-mapping><servlet-name>uploadFile</servlet-name><url-pattern>/uploadFile</url-pattern></servlet-mapping>
</web-app>

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%String path = request.getContextPath();String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";
%><!DOCTYPE html>
<html><head><title>上传文件</title><base href="<%=basePath%>"><meta http-equiv="content-type" content="text/html; charset=UTF-8" /></head><body><form action="uploadFile" enctype="multipart/form-data" method="post"><table><tr><th>选择上传文件:</th><td><input name="file" type="file" /></td></tr><tr><th>上传服务器路径:</th><td><input name="uploadPath" type="text" placeholder="上传服务器路径" /></td></tr><tr><td colspan="2"><button type="submit">上传</button></td></tr></table></form></body></html>