1. 目录

[TOC]

2. 说明

异常解析器在发生异常的时候解析组装异常返回

3. 依赖分析

4. 源码分析

初始化异常解析器依然是在DispatchServlet#initStrategies()中完成的，方法为initHandlerExceptionResolvers()

4.1. initHandlerExceptionResolvers()

和前面一样，当配置<mvc:annotation-driven>的时候会加载默认，没有配置注解驱动，查询出来为空， 则会走后面getDefaultStrategies()

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private void initHandlerExceptionResolvers(ApplicationContext context) {
    this.handlerExceptionResolvers = null;

    if (this.detectAllHandlerExceptionResolvers) {
        //从容器中取出HandlerExceptionResolver
        Map<String, HandlerExceptionResolver> matchingBeans = BeanFactoryUtils
                .beansOfTypeIncludingAncestors(context, HandlerExceptionResolver.class, true, false);
        if (!matchingBeans.isEmpty()) {
            this.handlerExceptionResolvers = new ArrayList<>(matchingBeans.values());
            // We keep HandlerExceptionResolvers in sorted order.
            AnnotationAwareOrderComparator.sort(this.handlerExceptionResolvers);
        }
    }
    else {
        try {
            HandlerExceptionResolver her =
                    context.getBean(HANDLER_EXCEPTION_RESOLVER_BEAN_NAME, HandlerExceptionResolver.class);
            this.handlerExceptionResolvers = Collections.singletonList(her);
        }
        catch (NoSuchBeanDefinitionException ex) {
            // Ignore, no HandlerExceptionResolver is fine too.
        }
    }

    //没有的化加载默认的
    if (this.handlerExceptionResolvers == null) {
        this.handlerExceptionResolvers = getDefaultStrategies(context, HandlerExceptionResolver.class);
        if (logger.isTraceEnabled()) {
            logger.trace("No HandlerExceptionResolvers declared in servlet '" + getServletName() +
                    "': using default strategies from DispatcherServlet.properties");
        }
    }
}

5. 总结

6. 注意事项