@Autowired and static method

Blog Post: Using @Autowired in a Static Method: Finding a Simple Solution

👋 Hey there, tech enthusiasts! Are you facing the challenge of using the @Autowired annotation within a static method? 🤔 Don't worry, you're not alone! We've got your back with a simple hack to overcome this obstacle.

Imagine a scenario where you have a service, Foo, that needs to be autowired within a static method of another class, Boo. 💡 However, the current design doesn't allow you to change randomMethod() to be non-static. So, how do you ensure that you can still use the autowired Foo bean? Let's dive into the solution!

Understanding the Problem

Before we jump into the solution, let's quickly understand why using @Autowired in a static method is a no-go 🚫.

Unlike non-static methods, static methods do not have access to instance variables, including autowired beans. This limitation arises because static methods belong to the class rather than an instance of the class.

The Simple Hack: ApplicationContext

To workaround this limitation, we can use the ApplicationContext to manually fetch the autowired bean within the static method. 🌟

1. First, we need to ensure that the ApplicationContext is accessible throughout our application. One approach is to make it a static field in a singleton class:

   public class ApplicationContextProvider implements ApplicationContextAware { private static ApplicationContext context; public static ApplicationContext getApplicationContext() { return context; } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { context = applicationContext; } }

2. Next, we modify our Foo class to implement the InitializingBean interface. This allows us to fetch the autowired bean and store it in a static variable using the ApplicationContext:

   @Service public class Foo implements InitializingBean { private static Foo fooInstance; @Override public void afterPropertiesSet() { fooInstance = ApplicationContextProvider.getApplicationContext().getBean(Foo.class); } public int doStuff() { return 1; } public static Foo getFooInstance() { return fooInstance; } }

3. Finally, in the randomMethod() of the Boo class, we fetch the autowired Foo bean using the static method we added in Foo:

   public class Boo { public static void randomMethod() { Foo.getFooInstance().doStuff(); } }

And there you have it! 🎉 By utilizing the ApplicationContext and a simple hack, we were able to access the autowired Foo bean within a static method.

When to Use this Approach

Although this hack allows you to circumvent the limitations of using @Autowired in a static method, it is important to note that it should be used as a last resort.

When faced with scenarios where you cannot change the design to make the method non-static, or using a @Bean method in a configuration class is not feasible, the ApplicationContext hack is a viable solution. However, it's always recommended to refactor and design your codebase to follow best practices whenever possible. 😊

Engage with Us!

We hope this simple hack has helped you overcome the challenge of using @Autowired in a static method. If you have any questions, suggestions, or alternative approaches, we would love to hear from you! Leave a comment below and join the discussion. Let's learn and grow together! 👇

Happy coding! 💻✨