04、 struts1 总结一个简单的计数器

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RT，用struts1 来做一个简单的计数器，对struts1的基本用法有个总体的了解。

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1、首先要有个输入页面 input.jsp

<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%><!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=GB18030"><title>简易计算器</title></head><body><h1>简易计算器</h1><hr><form action="action/cal" method="post"><input type="text" name="value1"><select name="flag"><option value="+">+</option><option value="-">-</option><option value="*">*</option><option value="/">/</option></select><input type="text" name="value2"><input type="submit" value="="></form></body></html>

从这个页面中，我们可以知道有3 个属性， value1，value2，flag

2、那么，我们建立对应的Form

------------------------ CalActionForm.java

package com.wgy.struts;import org.apache.struts.action.ActionForm;public class CalActionForm extends ActionForm {private int value1;private String flag;private int value2;public int getValue1() {return value1;}public void setValue1(int value1) {this.value1 = value1;}public String getFlag() {return flag;}public void setFlag(String flag) {this.flag = flag;}public int getValue2() {return value2;}public void setValue2(int value2) {this.value2 = value2;}}

3、有Form出现了，就有相应的 Action出现

--------------------------- CalAction.java

package com.wgy.struts;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;public class CalAction extends Action {@Overridepublic ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {CalActionForm caf = (CalActionForm)form;int value1 = caf.getValue1();int value2 = caf.getValue2();String flag = caf.getFlag();int result = 0; try {if ("+".equals(flag)) {result = value1 + value2;}else if ("-".equals(flag)) {result = value1 - value2;}else if ("*".equals(flag)) {result = value1 * value2;}else if ("/".equals(flag)) {result = value1 / value2;}request.setAttribute("result", result);return mapping.findForward("success");}catch(Exception e) {e.printStackTrace();}return mapping.findForward("error");}}

为什么要有这句呢，request.setAttribute("result", result);

取得结果，也要在success.jsp中输出，所以要设一个值给它，用以取出。

因为0不能作为除数，所以，要try catch异常（异常做简单的处理就好了）；

当成功或，要转向相应的页面:

return mapping.findForward("success");

return mapping.findForward("error");

4、上面要想成功转向，还必须配置struts-config.xml 文件。

<?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.wgy.struts.CalActionForm"/></form-beans><action-mappings><action path="/cal"type="com.wgy.struts.CalAction"name="calForm"scope="request"attribute="testForm"><forward name="success" path="/success.jsp"/><forward name="error" path="/error.jsp"/></action></action-mappings></struts-config>

--------------- web.xml 文件

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list>  <servlet> <servlet-name>action</servlet-name> <servlet-class>org.apache.struts.action.ActionServlet</servlet-class> <init-param> <param-name>config</param-name> <param-value>/WEB-INF/struts-config.xml</param-value> </init-param> <init-param> <param-name>debug</param-name> <param-value>2</param-value> </init-param> <init-param> <param-name>detail</param-name> <param-value>2</param-value> </init-param> <load-on-startup>2</load-on-startup> </servlet>  <servlet-mapping> <servlet-name>action</servlet-name>  <url-pattern>/action/*</url-pattern> </servlet-mapping> </web-app>

5、那接下来，相应的success.jsp 和error.jsp 页面如下，要分别取得成功或失败的值

---------- success.jsp

<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%><%@ page import="com.wgy.struts.*" %> <!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=GB18030"><title>成功信息</title></head><body><%CalActionForm caf = (CalActionForm)request.getAttribute("testForm");%><%=caf.getValue1() %><%=caf.getFlag() %><%=caf.getValue2() %>=<%=request.getAttribute("result") %></body></html>

---------- error.jsp

<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%><%@ page import="com.wgy.struts.*" %> <!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=GB18030"><title>错误信息</title></head><body><%CalActionForm caf = (CalActionForm)request.getAttribute("testForm");%>计算失败：<br><%=caf.getValue1() %><%=caf.getFlag() %><%=caf.getValue2() %></body></html>

================== 大功告成 ================

在success.jsp 和error.jsp 页面中，会发现，取值的时候，用的是，

CalActionForm caf = (CalActionForm)request.getAttribute("testForm");

而不是

CalActionForm caf = (CalActionForm)request.getAttribute("calForm");

因为，在struts-config.xml文件中，

<action-mappings>
  <action path="/cal"
    type="com.wgy.struts.CalAction"
    name="calForm"
    scope="request"
    attribute="testForm"
  >

如果没写 attribute="testForm" 那么就用

CalActionForm caf = (CalActionForm)request.getAttribute("calForm");

跟name对应

如果写了，那就要用

CalActionForm caf = (CalActionForm)request.getAttribute("testForm");

而不用 calForm

04、 struts1 总结 一个简单的计数器

04、 struts1 总结一个简单的计数器