<global-results>
<result name="nullException">/WEB-INF/exception/nullException.jsp</result>
</global-results>
<global-exception-mappings>
<exception-mapping result="nullException" exception="java.lang.NullPointerException"></exception-mapping>
</global-exception-mappings>
exception-mapping中
a、exception：申明接收异常类型
b、result：接收到该类型异常返回结果
通过exception-mapping返回的结果，来找到对应的result