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 />