springMVC --全局异常处理（两种方式）

首先看springMVC的配置文件：

<!-- 全局异常配置 start -->
     <bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
         <property name="exceptionMappings">
             <props>
                 <prop key="java.lang.Exception">errors/error</prop>
                 <prop key="java.lang.Throwable">errors/err</prop>
             </props>
         </property>
         <property name="statusCodes">
             <props>
                 <prop key="errors/error">500</prop>
                 <prop key="errors/404">404</prop>
             </props>
         </property>
         <!-- 设置日志输出级别，不定义则默认不输出警告等错误日志信息 -->
         <property name="warnLogCategory" value="WARN"></property>
         <!-- 默认错误页面，当找不到上面mappings中指定的异常相应视图时，使用本默认配置 -->
         <property name="defaultErrorView" value="errors/error"></property>
         <!-- 默认HTTP状态码 -->
         <property name="defaultStatusCode" value="500"></property>
     </bean>
     <!-- 全局异常配置 end -->

这里基本的类是SimpleMappingExceptionResolver类。和他的父类AbstractHandlerExceptionResolver类。

能够看到源代码中和上述配置相应的属性；

另外要注意的是日志

<span style="font-size:14px;"><property name="warnLogCategory" value="WARN"></property></span>

级别设置为WARN：

也能够实现HandlerExceptionResolver接口或者继承SimpleMappingExceptionResolver，写一个自己的异常处理程序

public class SpringMVCSimpleMappingExceptionResolver extends SimpleMappingExceptionResolver {

	public static final Log log = LogFactory.getLog(SpringMVCSimpleMappingExceptionResolver.class);

	@Override
	protected ModelAndView doResolveException(HttpServletRequest request,
			HttpServletResponse response, Object handler, Exception ex) {
		ModelAndView mv = null;
		String accept = request.getHeader("accept");
        if (accept != null && !(accept.indexOf("application/json") > -1
        		|| (request.getHeader("X-Requested-With") != null
        		&& request.getHeader("X-Requested-With").indexOf("XMLHttpRequest") > -1))) {
            mv = super.doResolveException(request, response, handler, ex);
        } else {
            try {
            	// json 请求返回
                PrintWriter writer = response.getWriter();
                writer.write(Return.failure((ex.getMessage())));
                writer.flush();
            } catch (IOException e) {
            	if (log.isInfoEnabled()) {
            		log.info(StringUtil.getTrace(e));
            	}
            }
        }
        doLog((HandlerMethod) handler, ex);
        return mv;
	}

	/**
	 * 记录异常日志
	 *
	 * @param handler
	 * @param excetpion
	 */
	private void doLog(HandlerMethod handler, Exception excetpion) {
        if (log.isEnabledExceptionDb()) {
        	// 异常信息日志入库
        }
	}
}