Struts温习(9)--关于异常的处理
本示例是以一个计算器的例子来写的，为了方便，这里处理的是算术异常
index.jsp
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<%@ page pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>Struts计算器</title> </head> <body> <h3>Struts应用：简单计算器</h3><hr/> <form action="${pageContext.request.contextPath}/manage/calculate.do" method="post"> <table border="1" width='500px'> <tr> <td>输入第一个数</td> <td><input type="text" name="num1"/></td> </tr> <tr> <td>选择运算符</td> <td> <select name="opt"> <option value="+"> + </option> <option value="-"> - </option> <option value="*"> * </option> <option value="/"> / </option> </select> </td> </tr> <tr> <td>输入第二个数</td> <td><input type="text" name="num2"/></td> </tr> <tr> <td colspan="2" align="center"> <input type="submit" value="执行计算"/></td> </tr> </table> </form> </body></html>?CalculateForm.java
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package com.javacrazyer.web.formbean;import org.apache.struts.action.ActionForm;public class CalculateForm extends ActionForm {private static final long serialVersionUID = 7273418667333097670L;private int num1;private int num2;private String opt;public int getNum1() {return num1;}public int getNum2() {return num2;}public void setNum2(int num2) {this.num2 = num2;}public void setNum1(int num1) {this.num1 = num1;}public String getOpt() {return opt;}public void setOpt(String opt) {this.opt = opt;}}?CalculateService.java
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package com.javacrazyer.web.action;public class CalculateService {public int calculate(int num1, int num2, String opt){int result = 0;if("+".equals(opt)){result = num1 + num2;}else if("-".equals(opt)){result = num1 - num2;}else if("*".equals(opt)){result = num1 * num2;}else if("/".equals(opt)){result = num1 / num2;}return result;}}?CalculateAction.java
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package com.javacrazyer.web.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import com.javacrazyer.web.formbean.CalculateForm;public class CalculateAction extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {//取数据CalculateForm cForm = (CalculateForm)form;int num1 = cForm.getNum1();int num2 = cForm.getNum2();String opt = cForm.getOpt();//执行业务逻辑CalculateService service = new CalculateService();//try{int result = service.calculate(num1, num2, opt);request.setAttribute("result", Integer.valueOf(result));//}catch(ArithmeticException ae){//ActionMessages errors = new ActionMessages();//ActionMessage err = new ActionMessage("出现算术异常情况了", false);//errors.add(ActionMessages.GLOBAL_MESSAGE, err);////放置到请求//this.saveErrors(request, errors);//return mapping.findForward("error_page");//}return mapping.findForward("result");}}?msg.properties
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arithmeticException.info=\u51FA\u73B0\u7B97\u672F\u5F02\u5E38\u60C5\u51B5\u4E86
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?WEB-INF/struts-config.xml
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<?xml version="1.0" encoding="ISO-8859-1" ?><!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_2.dtd"><struts-config><form-beans><form-bean name="calForm" type="com.javacrazyer.web.formbean.CalculateForm"/></form-beans><global-exceptions><exception key="xx.xx" type="xxx.DAOExcpetion" path="/innererror.jsp"/></global-exceptions><global-forwards><forward name="index" path="/index.jsp"/><forward name="error_page" path="/error.jsp"/></global-forwards><action-mappings><action path="/manage/calculate"name="calForm"type="com.javacrazyer.web.action.CalculateAction"scope="request"validate="false"><exception key="arithmeticException.info" type="java.lang.ArithmeticException" path="/error.jsp"/><forward name="result" path="/result.jsp"/><forward name="mysucc" path="/user_detail.jsp"/></action></action-mappings><message-resources parameter="msgs"/></struts-config>
上面action配置中就是专门配置的为算术异常处理的代码
?result.jsp
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<%@ page pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>Struts计算器</title> </head> <body> <h3>Struts应用：计算结果</h3><hr/> <table border="1" width='500px'> <tr> <td>您输入第一个数是: ${param.num1}</td> </tr> <tr> <td>您选择运算符是: ${param.opt}</td> </tr> <tr> <td>您输入第二个数是: ${param.num2}</td> </tr> <tr> <td>计算结果为: ${result}</td> </tr> <tr> <td align="center"> <input type="button" onclick="history.go(-1)" value=" 返回 "/></td> </tr> </table> </form> </body></html>?error.jsp
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<%@ page pageEncoding="UTF-8"%><%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %><%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <title>服务器内部出现异常</title> </head> <body> <h3>服务器内部出现异常</h3><hr/> <html:messages id="err"> <li><bean:write name="err"/></li> </html:messages> </body></html>
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计算正确的效果
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?计算错误的效果
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