Spring Boot: Exception Handling Best Practices
<p>Let’s provide a more detailed explanation for the real-life example of throwing custom exceptions from a service layer and handling them globally in a Spring Boot application for a product-related scenario.<br />
Steps:</p>
<p><strong>1. Create a Custom ProductNotFoundException:</strong></p>
<p>In this step, we create a custom exception class, <code>ProductNotFoundException</code>, which extends <code>RuntimeException</code>. This custom exception is used to represent situations where a product is not found in the system. By creating a custom exception, we can provide more specific information about the error.</p>
<pre>
public class ProductNotFoundException extends RuntimeException {
public ProductNotFoundException(Long productId) {
super(“Product not found with ID: “ + productId);
}
}</pre>
<p>Explanation:</p>
<ul>
<li>Custom exceptions are used to capture application-specific error scenarios.</li>
<li>In this case, we include the <code>productId</code> in the exception message to provide detailed information about the missing product.</li>
</ul>
<p><strong>2. Create a Product Service:</strong></p>
<p>Here, we create a <code>ProductService</code> class responsible for fetching product information. If a product is not found, it throws a <code>ProductNotFoundException</code>.</p>
<pre>
@Service
public class ProductService {
public Product getProductById(Long productId) {
// Simulate product retrieval logic
Product product = getProductFromDatabase(productId);
if (product == null) {
throw new ProductNotFoundException(productId);
}
return product;
}
// Simulated method to fetch a product from a database
private Product getProductFromDatabase(Long productId) {
// Implement your database logic here
// Return null if the product is not found
return null;
}
}</pre>
<p>Explanation:</p>
<ul>
<li>The <code>ProductService</code> encapsulates the business logic related to products.</li>
<li>The <code>getProductById</code> method simulates fetching a product from a database or another data source.</li>
<li>If the product is not found (based on the simulation), it throws a <code>ProductNotFoundException</code>.</li>
</ul>
<p><strong>3. Create a Global Exception Handler:</strong></p>
<p>This step involves creating a global exception handler using <code>@ControllerAdvice</code>. The handler is responsible for catching <code>ProductNotFoundException</code> globally and returning a custom error response.</p>
<p><a href="https://medium.com/@mailto.dipmazumder/spring-boot-exception-handling-best-practices-e8ebe97e8ce">Read More</a></p>