依赖jar
???????<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>
示例如下：
1. 新建Maven项目 upload
war 类型
2. pom.xml
<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>3. UploadFileServlet.java
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;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"; ???@Override ???protected 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); ???????????????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()); ???????????} ???????} ???} ???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(); ???????} ???}}4. web.xml
<?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>
5. 新建页面文件 src/main/webapp/index.jsp
<%@ 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>
部署到tomcat下，启动
浏览器输入 http://localhost:8080/upload/
如下所示：
选择文件，输入上传路径 G:\Temp\Test 如下所示：
单击【上传】，返回信息如下：
上传完成:G:\Temp\Test\fastjson-1.2.49.jar
查看G:\Temp\Test，文件已上传成功！
.
原生Servlet 上传文件
原文地址：https://www.cnblogs.com/jonban/p/10323620.html