详解SpringMVC使用MultipartFile实现文件的上传

发布时间：2020-12-14 14:34:55 所属栏目：Java 来源：网络整理

导读：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

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,File fileToUpload,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); 
  } 
 
  /** 
   * 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,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,fileNameToDownload,fileStoredPath); 
  } 
 
  private static final void transferFile(boolean isUpload,Map<String,String serverFileStoredName,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,String fileStoredPath,String  
 
fileStoredName) 
      throws SocketException,fileStoredPath,fileStoredName); 
  } 
   
  public static final void upload(Map<String,IOException { 
    if(fileStoredPath!=null && !"".equals(fileStoredPath)){ 
      serverCfg.put(WORKING_DIRECTORY,fileStoredPath); 
    } 
    upload(serverCfg,fileStoredName); 
  } 
   
  public static final void upload(String filePathToUpload,String fileStoredPath)throws SocketException,filePathToUpload,""); 
  } 
   
  public static final void upload(File fileToUpload,""); 
  } 
   
 
 
   
  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

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程小技巧。

（编辑：李大同）

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