| 來源 |
| jsp中有大量<% %>java片段 jsp中html標籤+jsp標籤+java片段 |
| 提出 |
| 把<% %>java片段用標籤替換 |
| C標籤 |
| <c:out>標籤 |
| 最常用的標籤，用於在 JSP 中顯示數據 |
|
<c:out value="hello
world" ></c:out>
<h1> 如何輸出request/session/application/pageContext域對象的內容 </h1>
<!--獲取“abc”中的值，如果獲取不到，默認值就是“hello”，escapeXml=false使得“abc”取到的文字中的html標籤可用
false【html形式】，true【文本形式】-->
<c:out value=" ${abc}" default ="hello" escapeXml="false" ></c:out>
|
|
<%
//如果域對象中有相同的屬性名，c:out的優先級是
//pageContext
> request > session > application
request.setAttribute( "abc","你好1<a
href='http://www.baidu.com'>baidu</a>");
session.setAttribute( "abc","你好2" );
application.setAttribute( "abc","你好3" );
pageContext.setAttribute( "abc","你好4" );
%>
|
| 獲取一個對象的元素 |
|
<!-- 如下兩種方式等價 -->
<c:out value=" ${xm.name}"></ c:out>
${xm.age}
|
| ${xm.age} 等價於 ((User)request.getAttribute("xm")).getAge() |
|
<%
User u = new User();
u.setName( "小明");
u.setAge(22);
request.setAttribute( "xm",u);
%>
|
| <c:set>標籤 |
|
<!-- 等價於request.setAttribute("abc","中國，北京")
-->
<c:set var="abc" value="中國，北京" scope ="request"></ c:set>
|
| <c:remove>標籤 |
|
<!-- 等價於request.setAttribute(" abc","中國，北京")
-->
<c:set var="a" value="中國，北京" scope ="request"></ c:set>
<c:out value=" ${a}"></ c:out>
<c:remove var="a" scope="request"></ c:remove>
<c:out value=" ${a}" default ="沒有了"></ c:out>
|
| <c:catch>標籤 |
|
<c:catch var="myexception" >
<%int a
= 8/0; %>
</c:catch>
<!-- 打印出捕獲的異常 -->
<c:out value=" ${myexception.message}"></ c:out>
|
| <c:if>標籤 |
|
<!-- 等價於request.setAttribute(a,"hello")
-->
<c:set var="a" value="hello" scope="request" ></c:set>
<!-- 等價於request.setAttribute(age,23)
-->
<c:set var="age" value="23" scope="request" ></c:set>
<!-- 如果a == 'hello'就輸出ACK! 否則輸出NCK!
-->
<c:if test=" ${a
== 'hello'}"> ACK!</c:if >
<c:if test=" ${a
!= 'hello'}"> NCK!</c:if >
<!--數值判斷
-->
<c:if test=" ${age
== 23}"> 23歲</c:if >
<c:if test=" ${age
>=18}"> 已經成年</c:if >
<!--獲取一個對象的屬性
-->
<c:if test=" ${u.name
== 'micky'}">
<c:out value=" ${u.age}"></ c:out>
</c:if>
|
|
<%
User user = new User();
user.setName( "micky");
user.setAge(1);
request.setAttribute( "u",user);
%>
|
| <c:choose><c:when><c:otherwise>標籤 |
|
<c:choose>
<c:when test=" ${rat.age
< 2}">
<font color="red" >娃娃</ font>
</c:when>
<c:when test=" ${rat.age
>=2 and rat.age < 5} ">
<font color="blue" >壯年</ font>
</c:when>
<c:otherwise>
<font color="green" >老年</ font>
</c:otherwise>
</c:choose>
|
|
<%
User u = new User();
u.setName( "rat");
u.setAge(10);
request.setAttribute( "rat",u);
%>
|
| <c:foreach>標籤 |
|
<!--取出array，並把沒次取出來的元素放在變量a
-->
<c:forEach items=" ${array}" var ="a">
<c:out value=" ${a.name}"></ c:out>
<c:out value=" ${a.age}"></ c:out>
</c:forEach>
<!--
從1-10依次打印 -->
<c:forEach begin="1" end="10" var="i" >
<c:out value=" [${i}] "></c:out >
</c:forEach>
<!--
從1-10隔3打印 -->
<c:forEach begin="1" end="10" step="3" var="i">
<c:out value=" [${i}] "></c:out >
</c:forEach>
|
|
<%
ArrayList<User> al = new ArrayList<User>();
User u1 = new User();
u1.setName( "老大");
u1.setAge(30);
User u2 = new User();
u2.setName( "老二");
u2.setAge(25);
User u3 = new User();
u3.setName( "老三");
u3.setAge(20);
al.add(u1);
al.add(u2);
al.add(u3);
request.setAttribute( "array",al);
%>
|
| <c:forToken>標籤 |
|
<!-- 從items中從0-7，隔2取出數據放入tmp，分隔符是‘，’ -->
<c:forTokens items="a,b,c,d,e,f,g" begin="0" end="7" step="2" delims="," var="tmp" >
${ tmp}
</c:forTokens>
|
