Upload Files with Spring MVC

Have you ever tried to upload a file as part of a form to be submited?
In my case I have a form to add or update products, and each product must have an image (JPG file), besides the regular information related to each product: Name, Description, etc.
Then, we need a form with some inputs and a method on one of my controllers to handle this request and we're set.

This topic is really simple to cover, despite of the fact is poorly covered by the official documentation.
Steps
Add entries on your POM <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>1.4</version> </dependency> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.2.1</version> </dependency>
Add a MultipartResolver in your Web Application Context <property name="maxUploadSize" value="50000"/><!-- in bytes --> <!-- There are more props, but I am not going to use them --> </bean>
On your form don't forget to include enctype attribute and make it POST

Add your input type file as regular HTML

In your controller add a method to handle with all params @RequestMapping(value="saveOrUpdateProduct.do", method=RequestMethod.POST) public String saveUpdateProduct(HttpServletRequest request, ModelMap modelMap, @ModelAttribute("ProductDTO") final ProductDTO productDTO, @RequestParam("productImage") final MultipartFile productImage, @RequestParam("brand") final Integer brand, @RequestParam("category") final Integer category){ if(!this.isLoggedIn(request)){//Verify if user is authenticated return "redirect:/authentication/notLoggedIn.do"; } Boolean result = false; File fileProductImage = new File(request.getSession().getServletContext().getRealPath("/img/products/")+File.separatorChar+productDTO.getCode()+".JPG"); //I'm going to upload all images into this directory and will assign them ext JPG log.debug("Save or Update products"); log.debug("fileProductImage="+fileProductImage); productDTO.getBrandDTO().setIdBrand(brand); productDTO.getCategoryDTO().setIdCategory(category); try { /*if(StringUtils.isEmpty(productDTO.getIdProduct()+"")){ result = this.catalogsService.addProduct(productDTO); }else{ result = this.catalogsService.modifyProduct(productDTO); } */ if(result){ log.debug("productDTO= "+productDTO+", idBrand= "+brand+", idCategory="+category); log.debug("FileUpload= "+productImage+", "+productImage.getContentType()+", "+productImage.getName()+", "+productImage.getOriginalFilename()+", "+productImage.getSize()); FileUtils.writeByteArrayToFile(fileProductImage, productImage.getBytes()); } } catch (Exception ex) { log.error(ex); modelMap.put(GenericConstants.KEY_ERROR, ex.getMessage()); } return getAllProducts(request, modelMap, null); }
I'm using FileUtils to save the uploaded file :D
Look carefully to this parameter @RequestParam("productImage") final org.springframework.web.multipart.MultipartFile productImage @RequestParam("productImage") matches to

And you're all set! Easy, Isn't it?

Static Binding vs Dynamic Binding

Today someone asked me if knew what was the difference between Static and Dynamic binding. I was in shock, because I didn't have any idea, I heard while on school (loooooooong time ago) something like that while my OOD teacher was explaining Overriding and Overloading (I always have problems trying to tell apart one from the other one), but this is my definition:
Overriding - always happens between classes in a hierarchy chain.
For example: when you extend from a Class and "override" an existing method to add a different behavior on the child class.

Overloading - can occur within a single class, and does not need to involve a class hierarchy.
For example: you can have on the same class multiple methods with same name and different params and even different return types.

Following the same order of ideas...
Static Binding: Static / Early binding is compile time binding. It means at compile time jvm decides which class member or method is preferred to call.
Dynamic binding: Late binding is run time binding. At run time jvm decides which method to call, depending on object type. Class A{ private int num = 10; public int getNum(){ return num; } } Class B extends A { private int num = 20; public int getNum(){ return num; } } A a = new A(); A a1 = new B();
Following my definitions:
Static Binding

a.num will be 10 and 
a1.num will be 10 

Dynamic binding

a.getNum() will return 10 
a1.getNum() will return 20 

Wooow! If you can't controll it don't smoke it dude!!!. Personally, this is good as General Culture Knowledge, but professionally, I think is better to have a good understanding of Overloading and Overriding.
Maybe , I'm too soft, but this is my humble perspective.

Simple reference: Quick ref on this matter