Struts温习(9)--关于异常的处理

JavaCrazyer

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框架-Struts专栏

Struts JSP Apache Bean Web

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

<%@ 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="+">&nbsp;+&nbsp;</option>
    					<option value="-">&nbsp;-&nbsp;</option>
    					<option value="*">&nbsp;*&nbsp;</option>
    					<option value="/">&nbsp;/&nbsp;</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

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

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

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

arithmeticException.info=\u51FA\u73B0\u7B97\u672F\u5F02\u5E38\u60C5\u51B5\u4E86

WEB-INF/struts-config.xml

<?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

<%@ 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

<%@ 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>

计算正确的效果