struts2异常处理，global-results定义全局结果处理

<global-results>定义全局结果处理

一般发生异常之后 结果返回errHandler

因为errHandler是由<global-exception-mappings>关联到Exception这个类了
然后处理结果

 <result name="errHandler" type="chain">

然后它就根据

<param name="actionName">errorProcessor</param>

找action

<action name="errorProcessor" class="cn.itcast.sh.error.ErrorProcess">
             <result>/error.jsp</result>
  </action>
处理了 然后 返回到 error.jsp

在struts.xml中

 <?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
     "http://struts.apache.org/dtds/struts-2.3.dtd">
 <struts>
     <constant name="struts.devMode" value="true" />
     <constant name="struts.enable.DynamicMethodInvocation" value="false"></constant>
     <!-- <constant name="struts.custom.i18n.resources" value="itcast"></constant> -->
     <package name="struts-global" namespace="/" extends="struts-default">
         <global-results>
             <result name="errHandler" type="chain">
                 <param name="actionName">errorProcessor</param>
             </result>
         </global-results>
         <global-exception-mappings>
             <exception-mapping result="errHandler" exception="java.lang.Exception">
             </exception-mapping>
         </global-exception-mappings>

         <action name="errorProcessor" class="cn.itcast.sh.error.ErrorProcess">
             <result>/error.jsp</result>
         </action>
     </package>

然后其他包都继承它 就默认使用了其中定义的 错误处理

然后实现 类

class="cn.itcast.sh.error.ErrorProcess"

 package cn.itcast.sh.error;

 import com.opensymphony.xwork2.ActionContext;
 import com.opensymphony.xwork2.ActionSupport;

 public class ErrorProcess extends ActionSupport {
     private Exception exception;

     public Exception getException() {
         return exception;
     }

     public void setException(Exception exception) {
         this.exception = exception;
     }
     @Override
     public String execute()
     {
         ActionContext.getContext().getValueStack().push(this.exception.getMessage());　　　　　　//放到值栈顶
         return this.SUCCESS;
     }
 }

例子

struts.xml配置

 <?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
     "http://struts.apache.org/dtds/struts-2.3.dtd">
 <struts>
     <constant name="struts.devMode" value="true" />
     <constant name="struts.enable.DynamicMethodInvocation" value="false"></constant>
     <!-- <constant name="struts.custom.i18n.resources" value="itcast"></constant> -->
     <package name="struts-global" namespace="/" extends="struts-default">
         <global-results>
             <result name="errHandler" type="chain">
                 <param name="actionName">errorProcessor</param>
             </result>
         </global-results>
         <global-exception-mappings>
             <exception-mapping result="errHandler" exception="java.lang.Exception">
             </exception-mapping>
         </global-exception-mappings>

         <action name="errorProcessor" class="cn.itcast.sh.error.ErrorProcess">
             <result>/error.jsp</result>
         </action>
     </package>
     <include file="struts-user.xml"></include>
     <include file="struts-login.xml"></include>
 </struts>

struts-user.xml中

 <?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
     "http://struts.apache.org/dtds/struts-2.3.dtd">
 <struts>
     <package name="user" namespace="/" extends="struts-global">
         <action name="UserAction_*" method="{1}" class="cn.itcast.sh.action.UserAction">
             <result name="userList">/user/list.jsp</result>
         </action>
     </package>
 </struts>

然后 如果页面异常 都会转向 error.jsp中 显示

error.jsp可以进行错误显示

因为信息被放到栈顶了 所以可以取到

<s:property />