Spring MVC RESTful web service for file upload

In this project we are using java based configuration instead of xml based.

You need to configure multipartResolver which will help to accept multi part requests, along with it’s implementation (CommonsMultipartResolver). Also you can provide “maxUploadSize” etc.. properties.

package com.test.configuration;

import java.io.IOException;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration 
@ComponentScan("com.test")
@EnableWebMvc
public class Config extends WebMvcConfigurerAdapter {
 @Bean(name="multipartResolver") 
    public CommonsMultipartResolver getResolver() throws IOException{
        CommonsMultipartResolver resolver = new CommonsMultipartResolver();     
        
        //Set the maximum allowed size (in bytes) for each individual file.
        resolver.setMaxUploadSizePerFile(5242880);//5MB     
         
        return resolver;
    }
}

Below file represents the dispatcher servlet configuration:

package com.test.configuration;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration.Dynamic;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;


public class WebInitializer implements WebApplicationInitializer {

 public void onStartup(ServletContext servletContext) throws ServletException {        
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext(); 
        ctx.register(Config.class);  
        ctx.setServletContext(servletContext); 
        Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));  
        servlet.addMapping("/");  
        servlet.setLoadOnStartup(1);  
    }  
}

File Upload RestController

The class is marked up with @RestController annotation , which accept HTTP web-service requests and returns the response.

Simple uploadFile method is written which helps to upload file at destination location, In which you need to pass a MultipartFile as a method parameter e.g. @RequestParam(“file”) MultipartFile file.

package com.test.controller;

import java.io.File;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
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.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

@RestController
public class FileUploadController {

 @RequestMapping(value = "/upload", method = RequestMethod.POST)
 public ResponseEntity uploadFile(@RequestParam("file") MultipartFile file){
  
  String originalFilename = file.getOriginalFilename();
     File destinationFile = new File("C:\Ankur\testFiles\"+originalFilename);
     try {
                 
      file.transferTo(destinationFile);
   System.out.println("File path "+destinationFile.getPath());
   System.out.println("File size "+file.getSize());
  } catch (Exception e) {
   
   e.printStackTrace();
  }
  
  
  return new ResponseEntity(destinationFile.getPath(),HttpStatus.CREATED);
 }
}

Once the file will be uploaded, it will return the file path.

Testing

To verify this Rest API, I am using POSTMAN rest client.

Please follow the below instructions to send a POST request using POSTMAN client.

1. Create .war file and deploy on the tomcat server
2. Choose POST to be the selected HTTP method.
3. Specify the request URL as http://localhost:8081/FileUpload/upload
4. Do not add any header
5. Select form-data radio button under the Body, enter input parameter name as file, select file from drop down and finally select the file to upload.
6. Click on Send Button.
7. Server response with uploaded file path.