commonsmultipartresolver 的源码，可以研究一下 点我 前端代码：
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Insert title here</title> </head> <body> <form name="serForm" action="/SpringMVC006/fileUpload" method="post" enctype="multipart/form-data"> <h1>采用流的方式上传文件</h1> <input type="file" name="file"> <input type="submit" value="upload"/> </form> <form name="Form2" action="/SpringMVC006/fileUpload2" method="post" enctype="multipart/form-data"> <h1>采用multipart提供的file.transfer方法上传文件</h1> <input type="file" name="file"> <input type="submit" value="upload"/> </form> <form name="Form2" action="/SpringMVC006/springUpload" method="post" enctype="multipart/form-data"> <h1>使用spring mvc提供的类的方法上传文件</h1> <input type="file" name="file"> <input type="submit" value="upload"/> </form> </body> </html>配置代码：
<!-- 多部分文件上传 --> <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <!-- 上传图片最大大小100M（5M 5242440）--> <property name="maxUploadSize" value="104857600" /> <property name="maxInMemorySize" value="4096" /> <!-- 设置默认编码 --> <property name="defaultEncoding" value="UTF-8"></property> </bean>pom添加依赖：
<!-- 文件上传 --> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.3</version> </dependency>后台代码：
方式一：
/* * 通过流的方式上传文件 * @RequestParam("file") 将name=file控件得到的文件封装成CommonsMultipartFile 对象 */ @RequestMapping("fileUpload") public String fileUpload(@RequestParam("file") CommonsMultipartFile file) throws IOException { //用来检测程序运行时间 long startTime=System.currentTimeMillis(); System.out.println("fileName："+file.getOriginalFilename()); try { //获取输出流 OutputStream os=new FileOutputStream("E:/"+new Date().getTime()+file.getOriginalFilename()); //获取输入流 CommonsMultipartFile 中可以直接得到文件的流 InputStream is=file.getInputStream(); int temp; //一个一个字节的读取并写入 while((temp=is.read())!=(-1)) { os.write(temp); } os.flush(); os.close(); is.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } long endTime=System.currentTimeMillis(); System.out.println("方法一的运行时间："+String.valueOf(endTime-startTime)+"ms"); return "/success"; }方式二：
/* * 采用file.Transto 来保存上传的文件 */ @RequestMapping("fileUpload2") public String fileUpload2(@RequestParam("file") CommonsMultipartFile file) throws IOException { long startTime=System.currentTimeMillis(); System.out.println("fileName："+file.getOriginalFilename()); String path="E:/"+new Date().getTime()+file.getOriginalFilename(); File newFile=new File(path); //通过CommonsMultipartFile的方法直接写文件（注意这个时候） file.transferTo(newFile); long endTime=System.currentTimeMillis(); System.out.println("方法二的运行时间："+String.valueOf(endTime-startTime)+"ms"); return "/success"; }方式三：
/* *采用spring提供的上传文件的方法 */ @RequestMapping("springUpload") public String springUpload(HttpServletRequest request) throws IllegalStateException, IOException { long startTime=System.currentTimeMillis(); //将当前上下文初始化给 CommonsMutipartResolver （多部分解析器） CommonsMultipartResolver multipartResolver=new CommonsMultipartResolver( request.getSession().getServletContext()); //检查form中是否有enctype="multipart/form-data" if(multipartResolver.isMultipart(request)) { //将request变成多部分request MultipartHttpServletRequest multiRequest=(MultipartHttpServletRequest)request; //获取multiRequest 中所有的文件名 Iterator iter=multiRequest.getFileNames(); while(iter.hasNext()) { //一次遍历所有文件 MultipartFile file=multiRequest.getFile(iter.next().toString()); if(file!=null) { String path="E:/springUpload"+file.getOriginalFilename(); //上传 file.transferTo(new File(path)); } } } long endTime=System.currentTimeMillis(); System.out.println("方法三的运行时间："+String.valueOf(endTime-startTime)+"ms"); return "/success"; }我们看看测试上传的时间：
第一次我用一个4M的文件：
fileName：test.rar 方法一的运行时间：14712ms 方法二的运行时间：5ms 方法三的运行时间：4ms
第二次：我用一个50M的文件 方式一进度很慢，估计得要个5分钟
方法二的运行时间：67ms 方法三的运行时间：80ms
从测试结果我们可以看到：用springMVC自带的上传文件的方法要快的多！
对于测试二的结果：可能是方法三得挨个搜索，所以要慢点。不过一般情况下我们是方法三，因为他能提供给我们更多的方法。
附文件：
package com.datebook.web; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.URLEncoder; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import org.apache.commons.io.FileUtils; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpStatus; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.multipart.MultipartHttpServletRequest; import org.springframework.web.servlet.ModelAndView; import com.datebook.common.JsonResult; import com.datebook.common.ResultCode; @RestController @RequestMapping("/file") public class FileController { // 上传新的图像，删除原来的图像 /* UserInfoBean item = userService.loadUserInfoByUid(tmpuser.getUid()); * File df = new File(rootPath + item.getImgpath()); if (df.exists()) { df.delete(); }*/ /** * 单文件上传 */ @RequestMapping("/oneFileUpload") public JsonResult singleFileUpload(@RequestParam("file1")MultipartFile file1,HttpServletRequest request) throws Exception, IOException { String filePath = request.getServletContext().getRealPath("upload"); String filename = file1.getOriginalFilename(); System.out.println("----------------------"+filePath+"------------------------"); File targetFile = new File(filePath,filename); if (!targetFile.exists()) { targetFile.mkdirs(); } // 保存 try { file1.transferTo(targetFile); } catch (Exception e) { e.printStackTrace(); } //文件路径 String fullPath = targetFile.getPath(); String path = "upload/" + filename; Map<String, Object> map = new HashMap<>(); map.put("filePath", path); map.put("fullPath", fullPath); return new JsonResult(ResultCode.SUCCESS,"success",map); } /** * 多文件上传 */ @RequestMapping("/multipleFileUpload") public JsonResult multipleFileUpload(@RequestParam("files")MultipartFile[] files,HttpServletRequest request) throws Exception, IOException { String filePath = request.getServletContext().getRealPath("upload"); System.out.println("----------------------"+filePath+"------------------------"); List<String> path = new ArrayList<>(); List<String> fullPath = new ArrayList<>(); for(MultipartFile file:files){ String filename = file.getOriginalFilename(); File targetFile = new File(filePath,filename); if (!targetFile.exists()) { targetFile.mkdirs(); } // 保存 try { file.transferTo(targetFile); } catch (Exception e) { e.printStackTrace(); } /* String path1 = "upload/" + filename; String path2 = targetFile.getPath();*/ path.add("upload/" + filename); fullPath.add(targetFile.getPath()); } Map<String, Object> map = new HashMap<>(); map.put("filePath", path); map.put("fullPath", fullPath); return new JsonResult(ResultCode.SUCCESS,"success",map); } /** * 流上传 */ @RequestMapping(value = "requestFile", method = RequestMethod.POST) public ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse response) throws Exception { // 转型为MultipartHttpRequest： MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request; // 获得文件： MultipartFile file = multipartRequest.getFile("file"); // 获得文件名： String filename = file.getOriginalFilename(); // 获得输入流： InputStream input = file.getInputStream(); // 写入文件 file.transferTo(new File("E://"+filename)); System.out.println(filename); return null; } @RequestMapping("/fileDownload1") public ResponseEntity<byte[]> filedDownload1() throws IOException { //下载文件路径 String path="E:\\xiaomao.jpg"; File file=new File(path); HttpHeaders headers = new HttpHeaders(); //下载显示的文件名，解决中文名称乱码问题 String fileName=new String("小猫.jpg".getBytes("UTF-8"),"iso-8859-1"); //通知浏览器以attachment（下载方式）打开图片 headers.setContentDispositionFormData("attachment", fileName); //application/octet-stream ： 二进制流数据（最常见的文件下载） headers.setContentType(MediaType.APPLICATION_OCTET_STREAM); return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),headers, HttpStatus.CREATED); } @RequestMapping("/fileDownload2") public void fileDownload2(HttpServletRequest request,HttpServletResponse response) throws Exception{ //模拟文件，xiaomao.jpg为需要下载的文件 String fileName = request.getSession().getServletContext().getRealPath("upload")+"/xiaomao.jpg"; //获取输入流 InputStream bis = new BufferedInputStream(new FileInputStream(new File(fileName))); //假如以中文名下载的话 String filename = "xiaomao.jpg"; //转码，免得文件名中文乱码 filename = URLEncoder.encode(filename,"UTF-8"); //设置文件下载头 response.addHeader("Content-Disposition", "attachment;filename=" + filename); //1.设置文件ContentType类型，这样设置，会自动判断下载文件类型 response.setContentType("multipart/form-data"); BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream()); int len = 0; while((len = bis.read()) != -1){ out.write(len); out.flush(); } out.close(); } }