How to Create a Java Method Accessible Globally Within an API but Not from External Applications?

How can I implement a Java method that is globally accessible within my API but restricts access from external applications?

Implementing a method in Java that is accessible throughout your API but not from external applications involves the use of access modifiers and possibly a service layer design pattern. This ensures that while internal components of your API can call the method, external requests are restricted.

// Example of a Java class with a protected method
public class InternalService {
    protected void internalMethod() {
        // Implementation details here
    }
}

// In the same package, you can access it
public class SomeOtherService extends InternalService {
    public void callInternalMethod() {
        internalMethod(); // Accessible here
    }
}

// However, from a different package, it is not accessible
public class ExternalAccess {
    public void someMethod() {
        // Cannot call internalMethod() here
    }
}

Causes

• Improper use of access modifiers can expose internal methods to external applications.
• Lack of proper architecture design can lead to unintended access.

Solutions

• Use the 'protected' or 'package-private' access modifier if you aim to limit access to your method within the same package.
• Create a facade or service layer that selectively exposes functionality based on the context of the call.
• Implement authentication or API keys to control access to specific API endpoints.

Mistake: Using 'public' modifier inadvertently exposes the method to all external applications.

Solution: Always assess the visibility of your methods and use 'protected' or 'private' as appropriate.

Mistake: Not enforcing proper access checks in your API routes.

Solution: Implement authentication mechanisms that validate requests before allowing access to methods.