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Spring and Hibernate with Annotations

I have to admit it. I had the worst time with Hibernate when I first started learning it a few years ago.  Although I could see the power, the configuration inside Spring was a bit of a nightmare back then.

Today, both Spring and Hibernate support annotation-based configuration, which makes the whole process easier.  Combine this with Hibernate’s Auto-DDL ability (that is, automatic table creation), and it is quite simple to use Hibernate with Spring as long as you follow a few conventions.

The purpose of this article is to build a Hibernate managed Spring web application.  Here are the primary goals:

  • No SQL scripts, not even table creation scripts
  • Minimum XML configuration
  • Relationships defined by Java Persistence API (JPA) annotations
  • Read, write and edit two related classes
  • Make the framework extensible for adding other classes with minimal work

Full source code for this tutorial is available here.

UPDATE March 2014: This code is also available in GitHub at https://github.com/technologicaloddity/departments

Interested? Read on…

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Using the @PathVariable annotation in Spring MVC 3.0

Let’s say that you are creating an user account-based web application in Spring 3.0.  You would like to create a controller that would allow users to see each other’s profile by using a URL such as http://mysite/profile/username.  For example:

http://mysite/profile/Adam  would show user Adam’s profile.

http://mysite/profile/Baker would show user Baker’s profile.

Spring 3.0’s annotated controllers make this kind of mapping easy with the new @PathVariable mapping.

package com.technologicaloddity.hellowebapp;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class ShowProfileController {

    @RequestMapping("/profile/{username}")
    public String showProfile(Model model, @PathVariable("username") String username) {
        model.addAttribute("username", username);
        return "showProfile"; // the view name
    }
    
}

As you can see, the RequestMapping for the showProfile method has something a bit unusual: {username}.  This is a PathVariable, and it means that this method will serve any request of the format "/profile/someUserName".  We capture the actual username in the next line using the @PathVariable annotation, and store it in the String username.  Now we can use it however we want!

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