11、 Exception handler

1、 Configuration based exception handling

SpringMVC It provides an interface to handle exceptions during the execution of controller methods ：HandlerExceptionResolver

HandlerExceptionResolver The implementation classes of the interface are ：DefaultHandlerExceptionResolver and SimpleMappingExceptionResolver

SpringMVC Provides a custom exception handler SimpleMappingExceptionResolver, Usage mode ：

    <!-- Exception handler -->
    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <!--
                    prop The key of represents an exception that occurs during the execution of the processor method 
                    prop The value of indicates that if a specified exception occurs , Set a new view name , Jump to the specified page 
                -->
                <prop key="java.lang.ArithmeticException">error</prop>
            </props>
        </property>

        <!--
            exceptionAttribute: Set a property name , Share the exception information in the request domain 
        -->
        <property name="exceptionAttribute" value="ex"></property>
    </bean>

2、 Annotation based exception handling

//@ControllerAdvice Identify the current class as the exception handling component 
@ControllerAdvice
public class ExceptionController {
    

    //@ExceptionHandler Used to set the exception handled by the identified method 
    @ExceptionHandler(ArithmeticException.class)
    //ex Represents the exception object in the current request processing 
    public String handleArithmeticException(Exception ex, Model model){
    
        model.addAttribute("ex", ex);
        return "error";
    }

}