Spring File Upload

Spring is a framework which provides almost all types of functionality. Spring has feature to stream based file upload. Spring file upload is very easy and maintainable. Spring provides the api to upload file streams. Like java IO spring has some classes to process file streams. To let the spring framework work for you, you need some jars in your lib, put following code in maven pom.xml to fetch dependencies :

<!-- Apache Commons FileUpload -->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>

<!-- Apache Commons IO -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>

Spring provides the class CommonsMultipartResolver to process stream based operations.

ApplicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<mvc:annotation-driven />  
<context:component-scan base-package="org.evon.springFileUpload.controller"/>

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix">
        <value>/jsp/</value>
    </property>
    <property name="suffix">
        <value>.jsp</value>
    </property>
</bean>
 <bean id="multipartResolver"
     class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- max upload size in bytes -->
        <property name="maxUploadSize" value="20971520" /> <!-- 20MB -->

        <!-- max size of file in memory (in bytes) -->
        <property name="maxInMemorySize" value="1048576" /> <!-- 1MB -->
 </bean>
</beans>

FileUploadController.java

package org.evon.springFileUpload.controller;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import org.apache.log4j.Logger;
import org.fileUpload.service.FileUploadService;
import org.fileUpload.service.UserInfoService;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.ModelAttribute;
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.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
public class FileUploadController implements HandlerExceptionResolver{
    private static final Logger logger = Logger.getLogger(FileUploadController.class);
    /**
     * render the File Upload Page
     * @return
     */
    @RequestMapping(value = {"/fileUpload","/fileUpload/upload" } ,method = RequestMethod.GET)
    public ModelAndView viewUploadPage() {
        ModelAndView model = new ModelAndView("FileUploadPage");
        return model;
    }

    /**
     * Upload file
     */
    @RequestMapping(value = "/fileUpload/upload", method = RequestMethod.POST)
    public String uploadFileHandler(BindingResult result, @RequestParam("fileName") MultipartFile fileName, Model model, RedirectAttributes redir, HttpServletRequest request, HttpSession session) {
        UserFileInfo dbFileInfo=null;
        long fileId = userFileInfo.getId();
        if (!fileName.isEmpty()) {
           try {
            String uploadFileName = fileName.getOriginalFilename();     
                String uploadDirPath = System.getProperty("catalina.home");;
                //if edit file then create a revision of file.
                uploadDirPath = uploadDirPath + File.separator + uploadFileName;

                 // Create the file on server
                File serverFile = new File(uploadDirPath);
        byte[] bytes = fileName.getBytes();
                BufferedOutputStream stream = new BufferedOutputStream( new FileOutputStream(serverFile));
                stream.write(bytes);
                stream.close();
                logger.info("Server File Location : " + serverFile.getAbsolutePath());
                redir.addFlashAttribute("successMessage", "You successfully uploaded file " + uploadFileName);
                return "redirect:/fileUpload";
            } catch (Exception e) {
                redir.addFlashAttribute("errorMessage", "Failed to upload ");
                e.printStackTrace();
                return "redirect:/fileUpload";
            }
        } else {
            model.addAttribute("errorMessage", "Failed to upload because the file was empty.");
            return "/FileUploadPage";
        }
    }

 @Override
    public ModelAndView resolveException(HttpServletRequest req, HttpServletResponse res, Object arg, Exception exception) {
        Map<Object, Object> model = new HashMap<Object, Object>();
        if (exception instanceof MaxUploadSizeExceededException){
            model.put("errorMessage", "The file should be less then "+
            ((MaxUploadSizeExceededException)exception).getMaxUploadSize()+" byte.");
        } else{
            model.put("errorMessage", "Unexpected error: " + exception.getMessage());
        }
        return new ModelAndView("/FileUploadPage", (Map) model);
    }   
}

FileUploadPage.jsp

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title>Upload File Page</title>
</head>
<body>
    <form method="POST" action="/fileUpload/upload" enctype="multipart/form-data">
        File : <input type="file" name="fileName"><br />
        <input type="submit" value="Upload File">
    </form>
</body>
</html>