Spring Boot Global Exception Handler

A reusable Spring Boot library for centralized exception handling.
This library provides a common Global Exception Handler that can be used across multiple Spring Boot projects as a Maven dependency.

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Purpose

• Avoid writing duplicate @ControllerAdvice in every project
• Standardize API error responses
• Handle validation, business, and system exceptions centrally

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Features

• Global exception handling using @ControllerAdvice
• Supports validation errors (@Valid)
• Supports custom business exceptions (ApiException)
• Handles runtime and system exceptions
• Auto-configured using Spring Boot auto-configuration

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Maven Dependency

<dependency>
    <groupId>com.icodetech</groupId>
    <artifactId>sbglobalexceptionhandler</artifactId>
    <version>1.0</version>
</dependency>

⚙️ Auto Configuration

• This library uses Spring Boot AutoConfiguration.
• You do NOT need to add any @ControllerAdvice in your project.
• Auto-configuration class:

GlobalExceptionAutoConfiguration

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Use Annotation in Main Application Class

📌 Application.java

@SpringBootApplication
@EnableGlobalExceptionHandling
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

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🧩 Supported Exceptions

1️⃣ Validation Errors

• Triggered when @Valid fails.
• Example DTO:

public class TestRequest {

    @NotBlank(message = "name is mandatory")
    private String name;

    @NotNull(message = "age is required")
    private Integer age;
} 

• Controller:

@PostMapping("/validate")
public String validate(@Valid @RequestBody TestRequest request) {
    return "SUCCESS";
} 

• Response:

{
  "responseCode": 400,
  "responseMessage": "Validation Errors",
  "errors": [
    {
      "fieldName": "name",
      "message": "name is mandatory"
    },
    {
      "fieldName": "age",
      "message": "age is required"
    }
  ]
}

2️⃣ Business Exception (ApiException)

• Throw anywhere in your code:

throw new ApiException(HttpStatus.BAD_REQUEST, "Invalid business rule");

• Response:

{
  "responseCode": 400,
  "responseMessage": "Invalid business rule",
  "errors": {
    "message": "Invalid business rule"
  }
}

3️⃣ System / Runtime Exception

• Example:

String value = null;
value.toString();

• Response:

{
  "responseCode": 400,
  "responseMessage": "Error occurred",
  "errors": {
    "message": "Cannot invoke \"String.toString()\" because \"value\" is null"
  }
}

🚫 What NOT to Do

• ❌ Do NOT create your own @ControllerAdvice
• ❌ Do NOT override exception handling in consumer projects

The library handles everything automatically.

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🔍 Debugging Auto Configuration

Enable logs:

logging.level.org.springframework.boot.autoconfigure=DEBUG

Startup log should contain:

GlobalExceptionAutoConfiguration matched

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🧠 Supported Exception Types

• ApiException
• MethodArgumentNotValidException
• HttpMessageNotReadableException
• MissingServletRequestParameterException
• MethodArgumentTypeMismatchException
• TypeMismatchException
• NoHandlerFoundException
• SQLIntegrityConstraintViolationException
• RuntimeException
• Exception

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🛠️ Tech Stack

• Java 8+
• Spring Boot 2.7.x
• Maven

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📄 License

This project is licensed under the Apache License, Version 2.0.

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👨‍💻 Author

iCode Technology

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🛣️ Roadmap

• Spring Boot 3.x support
• Error code enum support
• Property-based enable/disable
• RFC 7807 (Problem Details) support
• Logging & trace-id integration