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Struts2学习第八课 声明式异常处理
异常处理:exception-mapping元素
exception-mapping元素:配置当前的action的声明式异常处理
exception-mapping元素有两个属性:
--exception:指定需要铺货的异常类型
--result:指定一个响应结果,该结果将在捕获到指定异常时被执行,既可以来自当前action的声明也可以来自global-results声明。
可以通过global-exception-mappings元素为应用程序提供一个全局性的异常补货映射,但是在global-exception-mapping元素下声明的任何exception-mapping元素只能在global-results元素下声明的某个result元素。
声明式异常处理机制由ExceptionMappingInteceptor拦截器负责处理,当某个exception-mapping元素声明的异常被捕获到时,ExceptionMappingInterceptor拦截器就会向ValueStack中添加两个对象:
--exception:表示被捕获异常的Exception对象
--exceptionStack:包含着呗捕获异常的栈
可以在视图上通过<s:property/>标签显示异常消息
看代码:
package logan.struts.study; 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); ValueStack valueStack = ActionContext.getContext().getValueStack(); Test test = new Test(); test.setProductDesc("AABBCCDD"); test.setProductName("ABCD"); valueStack.push(test); session.put("product", this); request.put("test", test); int i = 10/0; return "success"; } private Map<String, Object> session; private Map<String, Object> request; @Override public void setSession(Map<String, Object> session) { // TODO Auto-generated method stub this.session = session; } @Override public void setRequest(Map<String, Object> request) { // TODO Auto-generated method stub this.request = request; } }
package logan.struts.study; public class Test { private String productName; private String productDesc; 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; } }
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> <!-- 打开静态方法调用的限制 --> <constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant> <package name="default" namespace="/" extends="struts-default"> <action name="product-save" class="logan.struts.study.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>
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>struts2-5</display-name> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> </welcome-file-list> </web-app>
details.jsp
<%@page import="java.util.HashMap"%> <%@page import="java.util.Map"%> <%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@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=ISO-8859-1"> <title>Insert title here</title> </head> <body> <s:debug></s:debug> productId:${productId } <br><br> productName:${productName } <br><br> productDesc:${productDesc } <br><br> productPrice:${productPrice } <br><br> productPrice:<s:property value="productPrice"/> <br><br> productName1:${sessionScope.product.productName } <br><br> productName1.1:<s:property value="#session.product.productName"/> <br><br> productName2:${requestScope.test.productName } <br><br> productName2.1:<s:property value="#request.test.productName"/> <br><br> <!-- 使用 OGNL 调用public 类的public类型的静态字段和静态方法 --> <s:property value="@java.lang.Math@PI"/> <br><br> <s:property value="@java.lang.Math@cos(0)"/> <br><br> <!-- 调用对象栈的方法为一个属性赋值 --> <s:property value="setProductName(‘logan‘)"/> <br><br> <s:property value="productName"/> <br><br> <% String [] names = new String[]{"aa","bb","cc","dd"}; request.setAttribute("names", names); %> length: <s:property value="#attr.names.length"/> <br><br> names[2]:<s:property value="#attr.names[2]"/> <br><br> <% Map<String,String> letters = new HashMap<String,String>(); request.setAttribute("letters", letters); letters.put("AA", "a"); letters.put("BB", "b"); letters.put("CC", "c"); %> <!-- 使用OGNL访问Map --> <s:property value="#attr.letters.size"/> <br><br> AA:<s:property value="#attr.letters[‘AA‘]"/> </body> </html>
input.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <%@ 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=ISO-8859-1"> <title>Insert title here</title> </head> <body> <s:debug></s:debug> <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"> <br><br> </form> </body> </html>
Struts2学习第八课 声明式异常处理
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