clayclayclay/mvc-exceptions

Demo of points covered on my MVC Exceptions blog

mvc-exceptions

NOTES:

• This project is built using release 1.1.8 of Spring Boot, Java 8 and Spring 4.1 - see pom.xml.
• The POM builds a JAR file, not a WAR, so you must run it as a Java application. Use mvn exec:java or mvc spring-boot:run to run it, then goto http://localhost:8080.

This application demos most of the points covered on my MVC Exceptions blog: https://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc.

This demo is running on Cloud Foundry at http://mvc-exceptions-v2.cfapps.io/.

Release History

• November 2013: V1
• October 2014: V2

Application Overview

The most significant files are:

Demo 1

Controller with @ExceptionHandler methods

• src/main/java/demo1/web/ExceptionHandlingController.java
  • A controller that raises exceptions and provides its own handlers to catch and process them.

Demo 2

Controller relying on a ControllerAdvice to handle its exceptions.

• src/main/java/demo2/web/ControllerWithoutExceptionHandlers.java
  • A controller with all the same handlers as ExceptionHandlingController (so they all throw exceptions) but no handler methods.
• src/main/java/demo2/web/GlobalControllerExceptionHandler.java
  • @ControllerAdvice class with all the same handlers as ExceptionHandlingController, but they would apply to all controllers.

Demo 3 and 4

Exception handling using a SimpleMappingExceptionResolver. When running in demo mode (profile is set to demo-config, which is setup by default), it defines a SimpleMappingExceptionResolver subclass that can be enabled (Demo 3) or disabled (Demo 4) to show the difference.

• src/main/java/demo3/config/DemoExceptionConfiguration.java
  • Java configuration to setup the beans for this demo.
• src/main/java/demo3/web/ExceptionThrowingController.java
  • Controller used by the demo.
• src/main/java/demo3/web/SwitchableSimpleMappingExceptionResolver.java
  • The resolver subclass described above.
• src/main/java/demo3/web/ExceptionThrowingController.java
  • Controller that provides /simpleMappingExceptionResolver/on and /simpleMappingExceptionResolver/off for switching the resolver on/off.

Demo 5

• ReturnOrRedirectController
  • Controller highlighting how Spring Boot implements its error-page mechanism.

Exceptions

• src/main/java/demo/exceptions/CustomException.java
• src/main/java/demo/exceptions/DatabaseException.java
• src/main/java/demo/exceptions/InvalidCreditCardException.java
• src/main/java/demo/exceptions/OrderNotFoundException.java
• src/main/java/demo/exceptions/UnhandledException.java
  • Custom exceptions - see blog for usage.
• src/main/java/org/springframework/dao/DataAccessException.java
  • Example of a predefined annotation, copied from Spring.
• src/main/java/org/springframework/dao/DataIntegrityViolationException.java
  • Example of a predefined annotation, copied from Spring.

Application Setup

The Demo configuration profile is useful for this demo application, but not typical. So two other profiles are provided to configure a SimpleMappingExceptionResolver in a more typical way using either Java configuration or an XML bean file.

• src/main/java/demo/main/Main.java
  • Main entry point for the application. Can run as a Java application (using an embedded Tomcat container) or as a WAR inside a container. Sets a few initialization properties and Spring Bean profile to use. Available profiles are demo-config (default), java-config, xml-config.
• src/main/java/demo/main/Profiles.java
  • The Spring Bean profiles used in the application.
• src/main/java/demo/config/ExceptionConfiguration.java
  • Java configuration class to setup a SimpleMappingExceptionResolver. Only used if the java-config profile is active.
• src/main/resources/mvc-configuration.xml
  • XML alternative to ExceptionConfiguration. Also sets up a SimpleMappingExceptionResolver. Only used if the xml-config profile is active.
• src/main/java/demo/config/ResponseDataControllerAdvice
  • Controller advice that puts useful data into the model for every request.

Utility Classes

• src/main/java/demo/utils/BeanLogger.java
  • Simple BeanPostProcessor to log all beans created. Not required by the demo, but as Spring Boot is new, it allows all the beans created to be logged.

Templates

All the views used, generated via Thymeleaf.

• src/main/resources/templates/creditCardError.html
• src/main/resources/templates/databaseError.html
• src/main/resources/templates/databaseException.html
• src/main/resources/templates/error.html
• src/main/resources/templates/exceptionPage.html
• src/main/resources/templates/support.html
• src/main/resources/templates/index.html (home page)

Build

• pom.xml
  • Maven POM - notice short it is - Spring Boot does most of the work. However heed the comments in the file.

Examples

Not used by the application, but provided as sample code.

• src/main/java/demo/example/ExampleExceptionHandlerExceptionResolver.java
  • Unused in the demo (to keep it simple), but implements the example discussed in the blog.
• src/main/java/demo/example/ExampleSimpleMappingExceptionResolver.java
  • Unused in the demo (to keep it simple), but implements the example shown in the blog (called MySimpleMappingExceptionResolver in the blog article).