Struts2_聲明式異常處理

異常處理：exception-mapping元素

execute-mapping元素: 配置當前action的聲明式異常處理

execute-mapping元素中有2個屬性
   --exception：指出需要捕獲的異常類型,異常全類名
   --result：指定一個響應結果，該結果將在捕獲到指定異常時被執行，既可以來自當前action的聲明，也可以來自global-result聲明。

	<action name="product-save"  class="com.wul.strust2.ValueStack.Product"
		        method="save">
		      <exception-mapping result="input" exception="java.lang.ArithmeticException"></exception-mapping> 
			<result name="input">/input.jsp</result>    
			<result>/details.jsp</result>
		</action>

可以通過global-exception-mappings元素爲應用程序提出一個全局性的異常捕獲映射。但在global-exception-mappings元素下聲明的

任何exception-mapping元素只能引用在global-result元素下聲明的某個result元素。(注意：global-result必須寫在global-exception-mappings前)

		<global-results>
			<result name="input">/input.jsp</result>
		</global-results>
		
		<global-exception-mappings>
			<exception-mapping result="input" exception="java.lang.ArithmeticException"></exception-mapping>
		</global-exception-mappings>

聲明式異常處理機制由ExceptionMappingInterceptor攔截器負責處理，當某個exception-mapping元素聲明的異常被捕獲到時，

ExceptionMappingInterceptor攔截器就會向ValueStack中添加兩個對象：
        --exception 表示被捕獲異常的Exception對象
                --exceptionStack包含着被捕獲異常的棧
 可以在視圖上通過<s:property>標籤顯示異常消息

下面給出範例

抓取  10/0 的異常

struts.xml

<?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>
	<!-- 打開靜態方法的調用 -->
	<constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>
	
    <package name="wul" namespace="/" extends="struts-default">
    
		<global-results>
			<result name="input">/input.jsp</result>
		</global-results>
		
		<global-exception-mappings>
			<exception-mapping result="input" exception="java.lang.ArithmeticException"></exception-mapping>
		</global-exception-mappings>
		
		
		<action name="product-save"  class="com.wul.strust2.ValueStack.Product"
		        method="save">
		<!--      <exception-mapping result="input" exception="java.lang.ArithmeticException"></exception-mapping> 
			<result name="input">/input.jsp</result>      -->
			<result>/details.jsp</result>
		</action>
    </package>

</struts>

Product.java

package com.wul.strust2.ValueStack;

import java.util.Map;

import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.util.ValueStack;

public class Product implements RequestAware,SessionAware{
	private Integer productId;
	private String productName;
	private String productDesc;
	private double productPrice;
	
	public Integer getProductId() {
		return productId;
	}
	public void setProductId(Integer productId) {
		this.productId = productId;
	}
	public String getProductName() {
		return productName;
	}
	public void setProductName(String productName) {
		this.productName = productName;
	}
	public String getProductDesc() {
		return productDesc;
	}
	public void setProductDesc(String productDesc) {
		this.productDesc = productDesc;
	}
	public double getProductPrice() {
		return productPrice;
	}
	public void setProductPrice(double productPrice) {
		this.productPrice = productPrice;
	}
	@Override
	public String toString() {
		return "Product [productId=" + productId + ", productName="
				+ productName + ", productDesc=" + productDesc
				+ ", productPrice=" + productPrice + "]";
	}
	
	public String save(){
		System.out.println("save: "+this.toString());
		
		<span style="color:#ff0000;">int i = 10 / 0;</span>
		
		//1.獲取值棧
		ValueStack valueStack = ActionContext.getContext().getValueStack();
		
		//2.創建Test對象，併爲其屬性賦值
		Test test = new Test();
		test.setProductDesc("wul");
		test.setProductName("520");
		
		//3.把Test對象壓入值棧的棧頂
		valueStack.push(test);
		
		//ProductPrice: <s:property value="[0].productPrice"/>會讀取“wul”和“520”
				
		sessionMap.put("product", this);
		requestMap.put("test", test);
		
		
		return "success";
	}
	
	private Map<String,Object> sessionMap;
	
	@Override
	public void setSession(Map<String, Object> sessionMap) {
		// TODO 自動生成的方法存根
		this.sessionMap = sessionMap;
	}
	
	private Map<String,Object> requestMap;
	@Override
	public void setRequest(Map<String, Object> requestMap) {
		// TODO 自動生成的方法存根
		this.requestMap = requestMap;
	}
}

input.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
    
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Hello</title>
</head>
<body>
	
	<s:debug></s:debug>
	<!--  
	<s:property value="exceptionStack"/>
	<br>
	-->
	<s:property value="exception"/>-
	${exception}
	<br>
	
	<s:property value="exception.message"/>-
	${exception.message}
	<br>
		

	<form action="product-save.action" method="post">
		ProductName:<input type="text" name="productName"/>
		<br><br>
		
		ProductDesc:<input type="text" name="productDesc"/>
		<br><br>
		
		ProductPrice:<input type="text" name="productPrice"/>
		<br><br>
		
		<input type="submit" value="Submit"/> 
	</form>
	
	
</body>
</html>