Struts2自學入門（六）——OGNL數據標籤和控制標籤

一、數據標籤

1.property標籤

<%
	request.setAttribute("name","<font color=red>張三</font>");
%>
</head>
<body>
<s:property value="#request.name" /><br/>
<s:property value="#request.name2" default="某某人"/><br/>
<s:property value="#request.name" default="某某人" escapeHtml="false"/><br/>

當值不存在時將使用default的值，escapeHtml可以將帶有HTML標籤的字符串轉化爲HTML輸出

2.set標籤

<s:set var="i" value="1"></s:set>
<s:property value="#i" /><br/>
<s:set var="a"  value="'action範圍的值'" scope="action"></s:set>
<s:set var="p"  value="'page範圍的值'" scope="page"></s:set>
<s:set var="r"  value="'request範圍的值'" scope="request"></s:set>
<s:set var="s"  value="'session範圍的值'" scope="session"></s:set>
<s:set var="app"  value="'application範圍的值'" scope="application"></s:set>
<s:property value="#a" /><br/>
<s:property value="#attr.p"/><br/>
<s:property value="#request.r"/><br/>
<s:property value="#session.s"/><br/>
<s:property value="#application.app"/><br/>

3.Bean標籤

<s:bean name="com.java1234.model.Student" var="student">
	<s:param name="name" value="'張三'"></s:param>
	<s:param name="age" value="10"></s:param>
</s:bean> 
<s:property value="#student.name"/>
<s:property value="#student.age"/>

4.date標籤

<%
	request.setAttribute("date",new Date());
%>

<body>
${date }<br/>
當前日期：<s:date name="#request.date" format="yyyy-MM-dd"/>
</body>

5.debug標籤
debug標籤主要用於輔助測試，它在頁面上生成一個超鏈接，通過該鏈接可以查看ValueStack和Stack Context 中的所有值信息。使用debug標籤只有一個id屬性，這個屬性僅僅是該元素一個引用id。在頁面上增加<s:debug/>標籤，通過debug標籤，可以看的系統中ValueStack離得全部信息，並可以看到Stack Context中的屬性。

<s:debug></s:debug>

6.url_a標籤

<s:url action="hello" namespace="/foreground" id="h">
	<s:param name="name" value="'struts2'"></s:param>
</s:url>
<s:a href="%{h}">超鏈接</s:a>

<s:a action="hello" namespace="/foreground">
	<s:param name="name" value="'struts2'"></s:param>
	超鏈接2
</s:a>

7.include標籤

<s:include value="head.html"></s:include>

二、控制標籤

1、ifelse標籤——條件判斷

<s:if test="#request.age<20">
	年齡小於20歲
</s:if>
<s:elseif test="#request.age==20">
	年齡等於20歲
</s:elseif>
<s:else>
	年齡大於20歲
</s:else>

2、iterator標籤——遍歷標籤

status屬性:可選屬性,該屬性在迭代時會產生一個IteratorStatus對象,該對象可以判斷當前元素的位置,包含了以下屬性方法:
int getCount(); 迭代元素個數
int getIndex(); 迭代元素當前索引
boolean getFirst(); 是否爲第一個
boolean getEven(); 是否爲偶
boolean getLast(); 是否最後一個
bolean getOdd(); 是否爲奇 (ps:#status.odd)

<%
	List<Student> studentList=new ArrayList<Student>();
	studentList.add(new Student(1,"張三",10));
	studentList.add(new Student(3,"李四",20));
	studentList.add(new Student(5,"王五",30));
	request.setAttribute("studentList",studentList);
%>
</head>
<body>
<table>
	<tr>
		<th>序號</th>
		<th>編號</th>
		<th>姓名</th>
		<th>年齡</th>
	</tr>
	<s:iterator value="#request.studentList" status="status">
	<tr>
		<td><s:property value="#status.index+1"/></td>
		<td><s:property value="id"/></td>
		<td><s:property value="name"/></td>
		<td><s:property value="age"/></td>
	</tr>
	</s:iterator>
</table>

3、append標籤——疊加

<%
	List<Student> studentList1=new ArrayList<Student>();
	List<Student> studentList2=new ArrayList<Student>();
	studentList1.add(new Student(1,"張三",10));
	studentList1.add(new Student(3,"李四",20));
	studentList2.add(new Student(5,"王五",30));
	studentList2.add(new Student(7,"趙六",40));
	request.setAttribute("studentList1",studentList1);
	request.setAttribute("studentList2",studentList2);
%>
</head>
<body>
<s:append var="studentList3">
	<s:param value="#request.studentList1"></s:param>
	<s:param value="#request.studentList2"></s:param>
</s:append>
<table>
	<tr>
		<th>序號</th>
		<th>編號</th>
		<th>姓名</th>
		<th>年齡</th>
	</tr>
	<s:iterator value="studentList3" status="status">
	<tr>
		<td><s:property value="#status.index+1"/></td>
		<td><s:property value="id"/></td>
		<td><s:property value="name"/></td>
		<td><s:property value="age"/></td>
	</tr>
	</s:iterator>
</table>

4、generator標籤——分隔標籤

<s:generator separator="," val="'張三,李四,王五'" var="nameList"></s:generator>

<s:iterator value="#nameList">
	<s:property/>
</s:iterator>

5、Merge標籤——組合標籤（混合疊加）

<%
	List<Student> studentList1=new ArrayList<Student>();
	List<Student> studentList2=new ArrayList<Student>();
	studentList1.add(new Student(1,"張三",10));
	studentList1.add(new Student(3,"李四",20));
	studentList2.add(new Student(5,"王五",30));
	studentList2.add(new Student(7,"趙六",40));
	request.setAttribute("studentList1",studentList1);
	request.setAttribute("studentList2",studentList2);
%>
</head>
<body>
<s:merge var="studentList3">
	<s:param value="#request.studentList1"></s:param>
	<s:param value="#request.studentList2"></s:param>
</s:merge>
<table>
	<tr>
		<th>序號</th>
		<th>編號</th>
		<th>姓名</th>
		<th>年齡</th>
	</tr>
	<s:iterator value="studentList3" status="status">
	<tr>
		<td><s:property value="#status.index+1"/></td>
		<td><s:property value="id"/></td>
		<td><s:property value="name"/></td>
		<td><s:property value="age"/></td>
	</tr>
	</s:iterator>
</table>

6、Sort標籤——排序標籤

<%
	List<Student> studentList1=new ArrayList<Student>();
	studentList1.add(new Student(1,"張三",20));
	studentList1.add(new Student(3,"李四",10));
	studentList1.add(new Student(5,"王五",40));
	studentList1.add(new Student(7,"趙六",30));
	request.setAttribute("studentList1",studentList1);
%>
</head>
<body>
<s:bean id="myComparator" name="com.java1234.comparator.MyComparator"></s:bean>



<table>
	<tr>
		<th>序號</th>
		<th>編號</th>
		<th>姓名</th>
		<th>年齡</th>
	</tr>
	<s:sort comparator="#myComparator" source="#request.studentList1" >
	<s:iterator status="status">
	<tr>
		<td><s:property value="#status.index+1"/></td>
		<td><s:property value="id"/></td>
		<td><s:property value="name"/></td>
		<td><s:property value="age"/></td>
	</tr>
	</s:iterator>
	</s:sort>
</table>
</body>

自定義排序規則 myComparator

public class MyComparator implements Comparator<Student>{

	public int compare(Student s1, Student s2) {
		if(s1.getAge()>s2.getAge()){
			return 1;
		}else if(s1.getAge()<s2.getAge()){
			return -1;
		}
		return 0;
	}

}

7、subset標籤——截取標籤

<%
	List<Student> studentList1=new ArrayList<Student>();
	studentList1.add(new Student(1,"張三",20));
	studentList1.add(new Student(3,"李四",10));
	studentList1.add(new Student(5,"王五",40));
	studentList1.add(new Student(7,"趙六",30));
	request.setAttribute("studentList1",studentList1);
%>
</head>
<body>

<table>
	<tr>
		<th>序號</th>
		<th>編號</th>
		<th>姓名</th>
		<th>年齡</th>
	</tr>
	<s:subset source="#request.studentList1" count="2" start="2">
	<s:iterator status="status">
	<tr>
		<td><s:property value="#status.index+1"/></td>
		<td><s:property value="id"/></td>
		<td><s:property value="name"/></td>
		<td><s:property value="age"/></td>
	</tr>
	</s:iterator>
	</s:subset>
</table>
</body>

Struts2自學入門（六）——OGNL數據標籤和控制標籤

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