【转载】struts标签使用举例--logic篇

本文摘自互联网

原文发表地址:http://www.javah.net/Struts/20070505/740.html

 <wbr>

1. <wbr> logic:empty

 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>该标签是用来判断是否为空的。如果为空,该标签体中嵌入的内容就会被处理。该标签用于以下情况:

 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>1)当Java对象为null时;

 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>2)当String对象为""时;

<wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>3)当java.util.Collection对象中的isEmpty()返回true时;

 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>4)当java.util.Map对象中的isEmpty()返回true时。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>eg. <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:empty  <wbr> name="userList"> <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>... <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> </logic:empty> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>该句等同于:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> if  <wbr> (userList.isEmpty())  <wbr> { <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>... <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>} <wbr> <wbr> <wbr>
 <wbr> <wbr> 2. <wbr> logic:notEmpty
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签的应用正好和logic:empty标签相反,略。
 <wbr> <wbr> 3. logic:equal
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签为等于比较符。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg1. <wbr>比较用户的状态属性是否1,若为1,输出"启用";
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:equal  <wbr> name="user"  <wbr> property="state"  <wbr> value="1">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 启用
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> </logic:equal>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg2. <wbr>如果上例中的value值是动态获得的,例如需要通过bean:write输出,因struts不支持标签嵌套,可采用EL来解决该问题。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:equal  <wbr> name="charge"  <wbr> property="num"  <wbr> value="${business.num}"> <wbr> <wbr> 
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> ......
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> </logic:equal>
 <wbr> <wbr> <wbr> <wbr>4. logic:notEqual
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>该标签意义与logic:equal相反,使用方法类似,略。
 <wbr> <wbr> <wbr> <wbr>5. logic:forward
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签用于实现页面导向,查找配置文件的全局forward。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg. <logic:forward name="index"/>
 <wbr> <wbr> <wbr> 6. logic:greaterEqual
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 为大于等于比较符。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg. <wbr>当某学生的成绩大于等于90时,输出“优秀”:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:greaterEqual name="student" property="score" value="90">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>优秀
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:greaterEqual>
 <wbr> <wbr> <wbr> 7. logic:greaterThan
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>
此为大于比较符,使用方法同logic:greaterEqual,略;
 <wbr> <wbr> <wbr> 8. logic:lessEqual
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>
此为小于等于比较符,使用方法同logic:greaterEqual,略;
 <wbr> <wbr> <wbr> 9. logic:lessThan
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>
此为小于比较符,使用方法同logic:greaterEqual,略;
 <wbr> <wbr> <wbr> 10. logic:match
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 此标签比较对象是否相等;
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg1. 检查在request范围内的name属性是否包含"amigo"串: <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:match name="name" scope="request" value="amigo">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="name"/>中有一个“amigo”串。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:match>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg2. 检查在request范围内的name属性是否已“amigo”作为起始字符串:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:match name="name" scope="request" value="amigo" location="start">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="name"/>以“amigo”作为起始字符串。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:match>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg3. <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:match header="user-agent" value="Windows">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>你运行的是Windows系统
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:match>
 <wbr> <wbr> <wbr> 11.  <wbr>logic:notMatch

 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 此标签用于比较对象是否不相同,与logic:match意义相反,使用方法类似,略。
 <wbr> <wbr> <wbr> <wbr> 12. logic:messagePresent
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签用于判断ActionMessages/ActionErrors对象是否存在;
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg. <wbr>如果存在error信息,将其全部输出:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:messagePresent property="error"> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><html:messages property="error" id="errMsg" > <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="errMsg"/> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></html:messages> <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:messagePresent >
 <wbr> <wbr> <wbr> <wbr> <wbr>13. logic:messagesNotPresent
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签用于判断ActionMessages/ActionErrors对象是否不存在,使用方法与logic:messagePresent类似,略
 <wbr> <wbr> <wbr> <wbr> <wbr> 14. logic:present
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 此标签用于判断request对象传递参数是否存在。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>  <wbr>eg1. user对象和它的name属性在request中都存在时,输出相应字符串:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:present name="user" property="name">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>user对象和该对象的name属性都存在
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:present> 
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg2. 若有一个名字为“user”的JavaBean,输出对应字符串:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:present name="user" >
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>有一个名字为“user”的JavaBean。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:present>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>eg3. <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:present header="user-agent">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>we got a user-agent header.
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:present>
 <wbr> <wbr> <wbr> <wbr> <wbr> 15. logic:notPresent
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 此标签用于判断request对象传递参数是否不存在,意义与了logic:present相反,使用方法类似,略。
 <wbr> <wbr> <wbr> <wbr> <wbr> 16. logic:redirect
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 该标签用于实现页面转向,可传递参数。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg1. <logic:redirect href="http://www.chinaitlab.com"/>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr>17. logic:iterator
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> 用于显示列表为collection的值(List ,ArrayList,HashMap等)。
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg1. <wbr>逐一输出用户列表(userlList)中用户的姓名:
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:iterate <wbr> id="user" name="userList">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="user" property="name"/><br>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> </logic:iterate>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg2. <wbr>从用户列表中输出从1开始的两个用户的姓名
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:iterate <wbr> id="user" name="userList" indexId="index" <wbr> offset="1" length="2">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="index"/>.<bean:write name="user" property="name"/><br>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:iterate>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> eg3. logic:iterator标签的嵌套举例
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <logic:iterate id="user" indexId="index" name="userList">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="index"/>. <bean:write name="user" property="name"/><br>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><logic:iterate id="address" name="user" property="addressList" length="3" offset="1">
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr><bean:write name="address"/><br>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:iterate>
 <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr> <wbr></logic:iterate>

电子时钟设计是一个基于单片机的综合性电子项目,涵盖硬件设计、软件设计、模块代码编写以及运行展示等多个环节。以下是该项目的详细分析与知识点总结: 电子时钟设计是一项课程设计任务,目标是开发一个功能完善的电子时钟系统。该系统以单片机为核心控制器,具备时间显示、设置和控制等功能,旨在满足用户的日常使用需求。 硬件设计的核心是系统方案原理图,它明确了系统的整体架构以及各组件之间的连接关系。外设设计方面,键盘输入模块和数码管显示模块是关键部分。键盘输入模块的工作原理包括键盘扫描、按键识别以及状态机控制等环节;数码管显示模块的工作原理则涉及数码管的驱动、显示控制和状态机控制等内容。 软件设计的核心是项目软件系统总架构图,它详细介绍了系统的软件框架,涵盖单片机编程、键盘输入模块流程图与代码、数码管显示模块流程图与代码等方面。顺序图则展示了软件的运行流程,包括系统初始化、键盘输入处理、显示控制和状态机控制等环节。 模块代码是系统各模块功能的具体实现。例如,键盘输入模块的代码实现了键盘扫描、按键识别和状态机控制等功能;数码管显示模块的代码实现了数码管驱动、显示控制和状态机控制等功能。 运行展示是项目的最终成果呈现环节,展示了电子时钟的实际运行效果,包括时间的准确显示、便捷的设置操作以及稳定的控制功能等。 单片机原理:掌握单片机的架构、指令系统和编程方法。 Proteus仿真:熟悉Proteus仿真原理、仿真环境及仿真操作。 C语言编程:理解C语言的语法、数据类型、控制结构、函数和数组等基础知识。 电子时钟设计:了解电子时钟的工作原理、设计方法和实现技术。 硬件设计:掌握硬件设计的基本原理、方法和工具。 软件设计:熟悉软件设计的基本原理、方法和工具。 模块代码实现:掌握模块代码的设计、编程和调试技巧。 电子时钟设计项目融合了硬件与软件设计,通过模块代码实现功能,并通过运行展示呈现最终效果。掌握
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值