使用Spring框架实现文件上传

在Java中实现文件的上传有多种方式，如smartUpload或是使用Strus2，本文与大家分享使用Spring框架中的MultipartFile类来实例文件的上传。

不啰嗦了，直接上干货。先是编写了一个实现文件上传的类FileUploadingUtil，此类中定义了两个对外公开的方法，upload和getFileMap。

前者需要传入一个Map参数，是用户提交的表单中的文件列表，最终返回值的也是一个Map类型对象，其键名为上传的文件名称，键值为文件在服务器上的存储路径；后者主要是用于测试用途，非主要功能，看官可以忽略此方法。

package com.emerson.cwms.utils;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.util.Date;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;import org.springframework.web.multipart.MultipartFile;/** * 文件上传工具类 *  * @author Chris Mao(Zibing) * */public class FileUploadingUtil {/** * 服务器上的保存路径，在使用到上传功能的Controller中对其进行赋值 */public static String FILEDIR = null;/** * 上传多个文件，返回文件名称和服务器存储路径列表 *  * @param files * @return * @throws IOException */public static Map<String, String> upload(Map<String, MultipartFile> files) throws IOException {File file = new File(FILEDIR);if (!file.exists()) {file.mkdir();}Map<String, String> result = new HashMap<String, String>();Iterator<Entry<String, MultipartFile>> iter = files.entrySet().iterator();while (iter.hasNext()) {MultipartFile aFile = iter.next().getValue();if (aFile.getSize() != 0 && !"".equals(aFile.getName())) {result.put(aFile.getOriginalFilename(), uploadFile(aFile));}}return result;}/** * 上传单个文件，并返回其在服务器中的存储路径 *  * @param aFile * @return * @throws FileNotFoundException * @throws IOException */private static String uploadFile(MultipartFile aFile) throws IOException {String filePath = initFilePath(aFile.getOriginalFilename());try {write(aFile.getInputStream(), new FileOutputStream(filePath));} catch (FileNotFoundException e) {logger.error("上传的文件: " + aFile.getName() + " 不存在！！");e.printStackTrace();}return filePath;}/** * 写入数据 *  * @param in * @param out * @throws IOException */private static void write(InputStream in, OutputStream out) throws IOException {try {byte[] buffer = new byte[1024];int bytesRead = -1;while ((bytesRead = in.read(buffer)) != -1) {out.write(buffer, 0, bytesRead);}out.flush();} finally {try {in.close();out.close();} catch (IOException ex) {}}}/** * 遍历服务器目录，列举出目录中的所有文件（含子目录） * @return */public static Map<String, String> getFileMap() {logger.info(FileUploadingUtil.FILEDIR);Map<String, String> map = new HashMap<String, String>();File[] files = new File(FileUploadingUtil.FILEDIR).listFiles();if (files != null) {for (File file : files) {if (file.isDirectory()) {File[] files2 = file.listFiles();if (files2 != null) {for (File file2 : files2) {String name = file2.getName();logger.info(file2.getParentFile().getAbsolutePath());logger.info(file2.getAbsolutePath());map.put(file2.getParentFile().getName() + "/" + name,name.substring(name.lastIndexOf("_") + 1));}}}}}return map;}/** * 返回文件存储路径，为防止重名文件被覆盖，在文件名称中增加了随机数 * @param name * @return */private static String initFilePath(String name) {String dir = getFileDir(name) + "";File file = new File(FILEDIR + dir);if (!file.exists()) {file.mkdir();}Long num = new Date().getTime();Double d = Math.random() * num;return (file.getPath() + "/" + num + d.longValue() + "_" + name).replaceAll(" ", "-");}/** *  * @param name * @return */private static int getFileDir(String name) {return name.hashCode() & 0xf;}}

Controller代码，使用上述定义的FileUploadingUtil类实现文件上传之功能。

package com.emerson.cwms.web;import java.io.IOException;import java.util.Iterator;import java.util.Map;import java.util.Map.Entry;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.stereotype.Controller;import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.multipart.MultipartHttpServletRequest;import com.emerson.cwms.utils.FileUploadingUtil;/** * 文件上传控制器 *  * @author Chris Mao(Zibing) * */@Controller@RequestMapping(value = "/files")public class FileController {@RequestMapping(value = "/", method = RequestMethod.GET)public String list(HttpServletRequest request, HttpServletResponse response, Model model) {iniFileDir(request);System.out.println(request.getAttribute("files"));model.addAttribute("files", FileUploadingUtil.getFileMap());return "files/list";}@RequestMapping(value = "/upload", method = RequestMethod.POST)public String doUpload(HttpServletRequest request) {iniFileDir(request);try {MultipartHttpServletRequest mRequest = (MultipartHttpServletRequest) request;Map<String, String> uploadedFiles = FileUploadingUtil.upload(mRequest.getFileMap());Iterator<Entry<String, String>> iter = uploadedFiles.entrySet().iterator();while (iter.hasNext()) {Entry<String, String> each = iter.next();System.out.print("Uploaded File Name = " + each.getKey());System.out.println(", Saved Path in Server = " + each.getValue());}} catch (Exception e) {e.printStackTrace();}return "redirect:/files/";}private void iniFileDir(HttpServletRequest request) {FileUploadingUtil.FILEDIR = request.getSession().getServletContext().getRealPath("/") + "files/";if (FileUploadingUtil.FILEDIR == null) {FileUploadingUtil.FILEDIR = request.getSession().getServletContext().getRealPath("/") + "files/";}}}

注意事项：一定要在pom.xml文件中添加对commons-fileupload的依赖引用，否则代码在运行时会提示找不到FileItemFactory类的错误。

依赖引用如下。

<dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version></dependency>