详解SpringMVC使用MultipartFile实现文件的上传

如果需要实现跨服务器上传文件，就是将我们本地的文件上传到资源服务器上，比较好的办法就是通过ftp上传。这里是结合SpringMVC+ftp的形式上传的。我们需要先懂得如何配置springMVC，然后在配置ftp，最后再结合MultipartFile上传文件。

springMVC上传需要几个关键jar包，spring以及关联包可以自己配置，这里主要说明关键的jar包

1：spring-web-3.2.9.RELEASE.jar (spring的关键jar包，版本可以自己选择)

2：commons-io-2.2.jar (项目中用来处理IO的一些工具类包)

配置文件

SpringMVC是用MultipartFile来进行文件上传的，因此我们先要配置MultipartResolver，用于处理表单中的file

<!-- 上传文件解释器 -->
 <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
   <property name="defaultEncoding" value="utf-8" />
   <property name="maxUploadSize" value="10485760" />
   <property name="maxInMemorySize" value="4096" />
   <property name="resolveLazily" value="true" />
 </bean>

其中属性详解：

defaultEncoding配置请求的编码格式，默认为iso-8859-1

maxUploadSize配置文件的最大单位，单位为字节

maxInMemorySize配置上传文件的缓存 ，单位为字节

resolveLazily属性启用是为了推迟文件解析，以便在UploadAction 中捕获文件大小异常

页面配置

在页面的form中加上enctype="multipart/form-data"

<form id="" name="" method="post" action="" enctype="multipart/form-data">

表单标签中设置enctype="multipart/form-data"来确保匿名上载文件的正确编码。

是设置表单的MIME编码。默认情况，这个编码格式是application/x-www-form-urlencoded，不能用于文件上传；只有使用了multipart/form-data，才能完整的传递文件数据，进行下面的操作。enctype="multipart/form-data"是上传二进制数据。form里面的input的值以2进制的方式传过去，所以request就得不到值了。

编写上传控制类

编写一个上传方法，这里没有返回结果，需要跳转页面或者返回其他值可以将void改为String、Map<String,Object>等值，再return返回结果。

   /**
* 上传
* @param request
* @return
*/
@ResponseBody
@RequestMapping(value = "/upload", method = {RequestMethod.GET, RequestMethod.POST})
public void upload(HttpServletRequest request) {
 MultipartHttpServletRequest multipartRequest=(MultipartHttpServletRequest)request;
 MultipartFile file = multipartRequest.getFile("file");//file是页面input的name名
 String basePath = "文件路径"
 try {
   MultipartResolver resolver = new CommonsMultipartResolver(request.getSession().getServletContext());
     if (resolver.isMultipart(request)) {
     String fileStoredPath = "文件夹路径";
     //随机生成文件名
     String randomName = StringUtil.getRandomFileName();
     String uploadFileName = file.getOriginalFilename();
     if (StringUtils.isNotBlank(uploadFileName)) {
       //截取文件格式名
       String suffix = uploadFileName.substring(uploadFileName.indexOf("."));
       //重新拼装文件名
       String newFileName = randomName + suffix;
       String savePath = basePath + "/" + newFileName;
       File saveFile = new File(savePath);
       File parentFile = saveFile.getParentFile();
       if (saveFile.exists()) {
         saveFile.delete();
       } else {
         if (!parentFile.exists()) {
           parentFile.mkdirs();
         }
       }
       //复制文件到指定路径
       FileUtils.copyInputStreamToFile(file.getInputStream(), saveFile);
       //上传文件到服务器
       FTPClientUtil.upload(saveFile, fileStoredPath);
     }
   }
 } catch (Exception e) {
   e.printStackTrace();
 }
}

FTP客户端上传工具

package com.yuanding.common.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.SocketException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
* FTP客户端工具
*/
public class FTPClientUtil {

/**
  * 日志
  */
 private static final Logger LOGGER = LoggerFactory.getLogger(FTPClientUtil.class);

/**
  * FTP server configuration--IP key,value is type of String
  */
 public static final String SERVER_IP = "SERVER_IP";

/**
  * FTP server configuration--Port key,value is type of Integer
  */
 public static final String SERVER_PORT = "SERVER_PORT";

/**
  * FTP server configuration--ANONYMOUS Log in key, value is type of Boolean
  */
 public static final String IS_ANONYMOUS = "IS_ANONYMOUS";

/**
  * user name of anonymous log in
  */
 public static final String ANONYMOUS_USER_NAME = "anonymous";

/**
  * password of anonymous log in
  */
 public static final String ANONYMOUS_PASSWORD = "";

/**
  * FTP server configuration--log in user name, value is type of String
  */
 public static final String USER_NAME = "USER_NAME";

/**
  * FTP server configuration--log in password, value is type of String
  */
 public static final String PASSWORD = "PASSWORD";

/**
  * FTP server configuration--PASV key, value is type of Boolean
  */
 public static final String IS_PASV = "IS_PASV";

/**
  * FTP server configuration--working directory key, value is type of String While logging in, the current directory
  * is the user's home directory, the workingDirectory must be set based on it. Besides, the workingDirectory must
  * exist, it can not be created automatically. If not exist, file will be uploaded in the user's home directory. If
  * not assigned, "/" is used.
  */
 public static final String WORKING_DIRECTORY = "WORKING_DIRECTORY";

public static Map<String, Object> serverCfg = new HashMap<String, Object>();

static Properties prop;

static{
   LOGGER.info("开始加载ftp.properties文件!");
   prop = new Properties();
   try {
     InputStream fps = FTPClientUtil.class.getResourceAsStream("/ftp.properties");
     prop.load(fps);
     fps.close();
   } catch (Exception e) {
     LOGGER.error("读取ftp.properties文件异常!",e);
   }
   serverCfg.put(FTPClientUtil.SERVER_IP, values("SERVER_IP"));
   serverCfg.put(FTPClientUtil.SERVER_PORT, Integer.parseInt(values("SERVER_PORT")));
   serverCfg.put(FTPClientUtil.USER_NAME, values("USER_NAME"));
   serverCfg.put(FTPClientUtil.PASSWORD, values("PASSWORD"));
   LOGGER.info(String.valueOf(serverCfg));
 }

/**
  * Upload a file to FTP server.
  *
  * @param serverCfg : FTP server configuration
  * @param filePathToUpload : path of the file to upload
  * @param fileStoredName : the name to give the remote stored file, null, "" and other blank word will be replaced
  *      by the file name to upload
  * @throws IOException
  * @throws SocketException
  */
 public static final void upload(Map<String, Object> serverCfg, String filePathToUpload, String fileStoredName)
     throws SocketException, IOException {
   upload(serverCfg, new File(filePathToUpload), fileStoredName);
 }

/**
  * Upload a file to FTP server.
  *
  * @param serverCfg : FTP server configuration
  * @param fileToUpload : file to upload
  * @param fileStoredName : the name to give the remote stored file, null, "" and other blank word will be replaced
  *      by the file name to upload
  * @throws IOException
  * @throws SocketException
  */
 public static final void upload(Map<String, Object> serverCfg, File fileToUpload, String fileStoredName)
     throws SocketException, IOException {
   if (!fileToUpload.exists()) {
     throw new IllegalArgumentException("File to upload does not exists：" + fileToUpload.getAbsolutePath

());
   }
   if (!fileToUpload.isFile()) {
     throw new IllegalArgumentException("File to upload is not a file:" + fileToUpload.getAbsolutePath());
   }
   if (StringUtils.isBlank((String) serverCfg.get(SERVER_IP))) {
     throw new IllegalArgumentException("SERVER_IP must be contained in the FTP server configuration.");
   }
   transferFile(true, serverCfg, fileToUpload, fileStoredName, null, null);
 }

/**
  * Download a file from FTP server
  *
  * @param serverCfg : FTP server configuration
  * @param fileNameToDownload : file name to be downloaded
  * @param fileStoredPath : stored path of the downloaded file in local
  * @throws SocketException
  * @throws IOException
  */
 public static final void download(Map<String, Object> serverCfg, String fileNameToDownload, String fileStoredPath)
     throws SocketException, IOException {
   if (StringUtils.isBlank(fileNameToDownload)) {
     throw new IllegalArgumentException("File name to be downloaded can not be blank.");
   }
   if (StringUtils.isBlank(fileStoredPath)) {
     throw new IllegalArgumentException("Stored path of the downloaded file in local can not be blank.");
   }
   if (StringUtils.isBlank((String) serverCfg.get(SERVER_IP))) {
     throw new IllegalArgumentException("SERVER_IP must be contained in the FTP server configuration.");
   }
   transferFile(false, serverCfg, null, null, fileNameToDownload, fileStoredPath);
 }

private static final void transferFile(boolean isUpload, Map<String, Object> serverCfg, File fileToUpload,
     String serverFileStoredName, String fileNameToDownload, String localFileStoredPath) throws  

SocketException,
     IOException {
   String host = (String) serverCfg.get(SERVER_IP);
   Integer port = (Integer) serverCfg.get(SERVER_PORT);
   Boolean isAnonymous = (Boolean) serverCfg.get(IS_ANONYMOUS);
   String username = (String) serverCfg.get(USER_NAME);
   String password = (String) serverCfg.get(PASSWORD);
   Boolean isPASV = (Boolean) serverCfg.get(IS_PASV);
   String workingDirectory = (String) serverCfg.get(WORKING_DIRECTORY);
   FTPClient ftpClient = new FTPClient();
   InputStream fileIn = null;
   OutputStream fileOut = null;
   try {
     if (port == null) {
       LOGGER.debug("Connect to FTP server on " + host + ":" + FTP.DEFAULT_PORT);
       ftpClient.connect(host);
     } else {
       LOGGER.debug("Connect to FTP server on " + host + ":" + port);
       ftpClient.connect(host, port);
     }
     int reply = ftpClient.getReplyCode();
     if (!FTPReply.isPositiveCompletion(reply)) {
       LOGGER.error("FTP server refuses connection");
       return;
     }

if (isAnonymous != null && isAnonymous) {
       username = ANONYMOUS_USER_NAME;
       password = ANONYMOUS_PASSWORD;
     }
     LOGGER.debug("Log in FTP server with username = " + username + ", password = " + password);
     if (!ftpClient.login(username, password)) {
       LOGGER.error("Fail to log in FTP server with username = " + username + ", password = " +  

password);
       ftpClient.logout();
       return;
     }

// Here we will use the BINARY mode as the transfer file type,
     // ASCII mode is not supportted.
     LOGGER.debug("Set type of the file, which is to upload, to BINARY.");
     ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

if (isPASV != null && isPASV) {
       LOGGER.debug("Use the PASV mode to transfer file.");
       ftpClient.enterLocalPassiveMode();
     } else {
       LOGGER.debug("Use the ACTIVE mode to transfer file.");
       ftpClient.enterLocalActiveMode();
     }

if (StringUtils.isBlank(workingDirectory)) {
       workingDirectory = "/";
     }

LOGGER.debug("Change current working directory to " + workingDirectory);
     changeWorkingDirectory(ftpClient,workingDirectory);

if (isUpload) { // upload
       if (StringUtils.isBlank(serverFileStoredName)) {
         serverFileStoredName = fileToUpload.getName();
       }
       fileIn = new FileInputStream(fileToUpload);
       LOGGER.debug("Upload file : " + fileToUpload.getAbsolutePath() + " to FTP server with name : "
           + serverFileStoredName);
       if (!ftpClient.storeFile(serverFileStoredName, fileIn)) {
         LOGGER.error("Fail to upload file, " + ftpClient.getReplyString());
       } else {
         LOGGER.debug("Success to upload file.");
       }
     } else { // download
       // make sure the file directory exists
       File fileStored = new File(localFileStoredPath);
       if (!fileStored.getParentFile().exists()) {
         fileStored.getParentFile().mkdirs();
       }
       fileOut = new FileOutputStream(fileStored);
       LOGGER.debug("Download file : " + fileNameToDownload + " from FTP server to local : "
           + localFileStoredPath);
       if (!ftpClient.retrieveFile(fileNameToDownload, fileOut)) {
         LOGGER.error("Fail to download file, " + ftpClient.getReplyString());
       } else {
         LOGGER.debug("Success to download file.");
       }
     }

ftpClient.noop();

ftpClient.logout();

} finally {
     if (ftpClient.isConnected()) {
       try {
         ftpClient.disconnect();
       } catch (IOException f) {
       }
     }
     if (fileIn != null) {
       try {
         fileIn.close();
       } catch (IOException e) {
       }
     }
     if (fileOut != null) {
       try {
         fileOut.close();
       } catch (IOException e) {
       }
     }
   }
 }

private static final boolean changeWorkingDirectory(FTPClient ftpClient, String workingDirectory) throws IOException{
   if(!ftpClient.changeWorkingDirectory(workingDirectory)){
     String [] paths = workingDirectory.split("/");
     for(int i=0 ;i<paths.length ;i++){
       if(!"".equals(paths[i])){
         if(!ftpClient.changeWorkingDirectory(paths[i])){
           ftpClient.makeDirectory(paths[i]);
           ftpClient.changeWorkingDirectory(paths[i]);
         }
       }
     }
   }
   return true;
 }

public static final void upload(Map<String, Object> serverCfg, String filePathToUpload, String fileStoredPath, String  

fileStoredName)
     throws SocketException, IOException {
   upload(serverCfg, new File(filePathToUpload), fileStoredPath, fileStoredName);
 }

public static final void upload(Map<String, Object> serverCfg, File fileToUpload, String fileStoredPath, String  

fileStoredName)
     throws SocketException, IOException {
   if(fileStoredPath!=null && !"".equals(fileStoredPath)){
     serverCfg.put(WORKING_DIRECTORY, fileStoredPath);
   }
   upload(serverCfg, fileToUpload, fileStoredName);
 }

public static final void upload(String filePathToUpload, String fileStoredPath)throws SocketException, IOException {
   upload(serverCfg, filePathToUpload, fileStoredPath, "");
 }

public static final void upload(File fileToUpload, String fileStoredPath)throws SocketException, IOException {
   upload(serverCfg, fileToUpload, fileStoredPath, "");
 }

public static String values(String key) {
   String value = prop.getProperty(key);
   if (value != null) {
     return value;
   } else {
     return null;
   }
 }

}

ftp.properties

#服务器地址
SERVER_IP=192.168.1.1

#服务器端口
SERVER_PORT=21

#帐号名
USER_NAME=userftp

#密码
#PASSWORD=passwordftp

来源：http://blog.csdn.net/w410589502/article/details/53906145