04、 struts1 總結一個簡單的計數器

RT，用struts1 來做一個簡單的計數器，對struts1的基本用法有個總體的瞭解。

------------------------------------------------

1、首先要有個輸入頁面 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>簡易計算器</title> </head> <body> <h1>簡易計算器</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>

從這個頁面中，我們可以知道有3 個屬性， value1，value2，flag

2、那麼，我們建立對應的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出現了，就有相應的 Action出現

--------------------------- 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 { @Override public 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"); } }

爲什麼要有這句呢，request.setAttribute("result", result);

取得結果，也要在success.jsp中輸出，所以要設一個值給它，用以取出。

因爲0不能作爲除數，所以，要try catch異常（異常做簡單的處理就好了）；

當成功或，要轉向相應的頁面:

return mapping.findForward("success");

return mapping.findForward("error");

4、上面要想成功轉向，還必須配置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、那接下來，相應的success.jsp 和error.jsp 頁面如下，要分別取得成功或失敗的值

---------- 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>錯誤信息</title> </head> <body> <% CalActionForm caf = (CalActionForm)request.getAttribute("testForm"); %> 計算失敗：<br> <%=caf.getValue1() %> <%=caf.getFlag() %> <%=caf.getValue2() %> </body> </html>

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

在success.jsp 和error.jsp 頁面中，會發現，取值的時候，用的是，

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

而不是

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

因爲，在struts-config.xml文件中，

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

如果沒寫 attribute="testForm" 那麼就用

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

跟name對應

如果寫了，那就要用

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

而不用 calForm

04、 struts1 總結一個簡單的計數器

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04、 struts1 總結 一個簡單的計數器

04、 struts1 總結一個簡單的計數器