前言

ControllerAdvice非常好用，可以把系统内部的异常统一处理。用起来也很简单。比如，http://www.cnblogs.com/woshimrf/p/spring-web-400.html

而Spring提供了一个base类ResponseEntityExceptionHandler，可以使用这个来处理。但用的时候要注意，不要重复定义异常捕获，对于base里已经定义好的，只要overwrite就好，不要重复声明异常拦截。

以下来自stackoverflow

问题

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@ControllerAdvice
public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {

    private Logger log = LoggerFactory.getLogger(RestResponseEntityExceptionHandler.class);

    @Autowired
    private ApplicationContext applicationContext;

    @ExceptionHandler({ ConstraintViolationException.class })
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ResponseBody
    public ErrorWrapper handleConstraintViolationException(ConstraintViolationException e) {
        String fieldName = e.getConstraintName();
        String message = getResourceMessage(fieldName + ".alreadyExists", "Already Exists");
        return new ErrorWrapper(fieldName + ".error", message);
    }

    @ExceptionHandler({ MethodArgumentNotValidException.class })
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ResponseBody
    public ErrorWrapper handleMethodArgumentNotValidException(MethodArgumentNotValidException e) {
        return new ErrorWrapper(".error", "test");
    }

    private String getResourceMessage(String key, String defaultMessage) {
        String message = applicationContext.getMessage(key, null, Locale.getDefault());
        if (StringUtils.isNotEmpty(message)) {
            return message;
        }
        return defaultMessage;
    }
}

将会得到以下异常：

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org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous @ExceptionHandler method mapped for [class org.springframework.web.bind.MethodArgumentNotValidException]: {public com.ca.bean.ErrorWrapper com.ca.exceptionHandler.RestResponseEntityExceptionHandler.handleMethodArgumentNotValidException(org.springframework.web.bind.MethodArgumentNotValidException), public final org.springframework.http.ResponseEntity org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler.handleException(java.lang.Exception,org.springframework.web.context.request.WebRequest)}
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:775) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:861) ~[spring-context-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541) ~[spring-context-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444) ~[spring-web-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326) ~[spring-web-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107) [spring-web-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5099) [catalina.jar:7.0.70]
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5615) [catalina.jar:7.0.70]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147) [catalina.jar:7.0.70]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571) [catalina.jar:7.0.70]
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561) [catalina.jar:7.0.70]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_92]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_92]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_92]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_92]
Caused by: java.lang.IllegalStateException: Ambiguous @ExceptionHandler method mapped for [class org.springframework.web.bind.MethodArgumentNotValidException]: {public com.ca.bean.ErrorWrapper com.ca.exceptionHandler.RestResponseEntityExceptionHandler.handleMethodArgumentNotValidException(org.springframework.web.bind.MethodArgumentNotValidException), public final org.springframework.http.ResponseEntity org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler.handleException(java.lang.Exception,org.springframework.web.context.request.WebRequest)}
    at org.springframework.web.method.annotation.ExceptionHandlerMethodResolver.addExceptionMapping(ExceptionHandlerMethodResolver.java:109) ~[spring-web-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.method.annotation.ExceptionHandlerMethodResolver.<init>(ExceptionHandlerMethodResolver.java:76) ~[spring-web-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.initExceptionHandlerAdviceCache(ExceptionHandlerExceptionResolver.java:265) ~[spring-webmvc-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.afterPropertiesSet(ExceptionHandlerExceptionResolver.java:241) ~[spring-webmvc-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574) ~[spring-beans-4.3.0.RELEASE.jar:4.3.0.RELEASE]
    ... 21 common frames omitted

异常堆栈标明，重复定义了异常拦截。那么如果继承了ResponseEntityExceptionHandler之后，想修改某些内容怎么办呢？

答案

只要重写父类方法即可。不要在重写的方法上声明拦截异常。

对于ResponseEntityExceptionHandler已经定义好的异常，不需要重新定义，只要重写方法就可以了。