jstl的几个标签
还是用代码说明：
jstlAction.java:
package com.keith.jstl;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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;
import com.keith.taglibs.Group;
import com.keith.taglibs.User;
public class JstlAction extends Action {
@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
// 字符串
request.setAttribute("hello", "hello JSTL");
// HTML文本
request.setAttribute("keith", "<font color='red'>keith</font>");
// 测试条件语句
request.setAttribute("v1", 1);
request.setAttribute("v2", 2);
request.setAttribute("v3", new ArrayList());
request.setAttribute("v4", "keith V4");
// 对象数组
Group group = new Group();
group.setGroupName("keith");
// 测试foreach
List userList = new ArrayList();
for (int i = 0; i < 10; i++) {
User u = new User();
u.setName("USER_" + i);
u.setAge(10 + i);
u.setGroup(group);
userList.add(u);
}
request.setAttribute("userList", userList);
// 测试循环输出map
Map map = new HashMap();
map.put("k1","v1");
map.put("k2","v2");
request.setAttribute("mapValue", map);
//测试c:forTokens
request.setAttribute("strTokens","1,2,3,4,5,6,7,8,9");
return mapping.findForward("jstl");
}
}
struts-config.xml:
<?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>
<action-mappings>
<action path="/jstl"
type="com.keith.jstl.JstlAction">
<forward name="jstl" path="/jstl.jsp"></forward>
</action>
</action-mappings>
<message-resources parameter="MessageResources" />
</struts-config>
jstl.jsp:首先指定标签库
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<body> </body>里：
<body>
c:out测试
<hr color="orange">
hello(JSTL_default):<c:out value="${hello}" /><br>
hello(EL_default):${hello }<br>
default(123):<c:out value="${abc}" default="123" /><br><!-- 找不到abc的值，这时的default就有了作用 -->
keith(c:out输出):<c:out value="${keith}" /><br>
keith(escapeXml="flase"):<c:out value="${keith}" escapeXml="flase"/><br>
keith(escapeXml="true"):<c:out value="${keith}" escapeXml="true"/><br>
keith(EL输出):${keith}
<hr>
c:set/remove测试
<hr color="orange">
<c:set var="set1" value="keithSET" /><br>
set1:${set1 }<br>
<c:remove var="set1"/><br>
set1:${set1 }<br>
<hr>
c:if：条件控制
<hr color="orange">
<c:if test="${v1 lt v2}" var = "v">
v1小于v2<br/>
${v }<br/>
</c:if>
<c:if test="${empty v3}">
v3为空<br/>
</c:if>
<c:if test="${empty v4}">
v4为空<br/>
</c:if>
<hr>
测试C:choose,c:when,c:otherwise
<hr color="orange">
<c:choose>
<c:when test="v1 lt v2">
v1小于v2<br/>
</c:when>
<c:otherwise>
v1不小于v2<br/>
</c:otherwise>
</c:choose>
<c:choose>
<c:when test="${empty v4}">
v4为空<br/>
</c:when>
<c:otherwise>
v4不为空<br/>
</c:otherwise>
</c:choose>
<hr>
<h4>测试c:forEach</h4>
<table >
<tr>
<td>姓名</td>
<td>年龄</td>
<td>组</td>
</tr>
<c:choose>
<c:when test="${empty userList}">
<tr>
<td colspan="3">没有符合条件的数据！</td>
</tr>
</c:when>
<c:otherwise>
<c:forEach items="${userList}" var="user" varStatus="vs">
<c:choose>
<c:when test="${vs.count % 2 == 0 }">
<tr bgcolor="orange">
</c:when>
<c:otherwise>
<tr>
</c:otherwise>
</c:choose>
<td>
<c:out value="${user.name}"></c:out>
</td>
<td>
<c:out value="${user.age}"></c:out>
</td>
<td>
<c:out value="${user.group.groupName}"></c:out>
</td>
</c:forEach>
</c:otherwise>
</c:choose>
</table>
<hr>
<h3>测试循环控制标签c:forEach,begin,end,step</h3>
<table>
<tr>
<td>姓名</td>
<td>年龄</td>
<td>组名</td>
</tr>
<c:choose>
<c:when test="${empty userList}">
<tr>
<td colspan="3">没又符合的数据</td>
</tr>
</c:when>
<c:otherwise>
<c:forEach items="${userList}" var="user" begin="2" end="5" step="2">
<tr>
<td>${user.name }</td>
<td>${user.age }</td>
<td>${user.group.groupName }</td>
</tr>
</c:forEach>
</c:otherwise>
</c:choose>
</table>
<p></p>
<hr>
<h4>测试循环控制标签 c:foreach 普通循环</h4>
<c:forEach begin="1" end="5">
a<br/>
</c:forEach><br>
<h4>测试循环控制标签c:forEach,输出map</h4>
<c:forEach items="${mapValue}" var="v">
${v.key } = ${v.value }<br/>
</c:forEach>
<h4>测试循环控制标签c:forTokens,用于有符号的表达式</h4>
<c:forTokens items="${strTokens}" delims="," var="v">
${v }<br/>
</c:forTokens>
<h4>测试c:catch</h4>
<%
try{
Integer.parseInt("keith");
}catch(Exception e){
out.println(e.getMessage());
}
%>
<p></p>
<c:catch var="exinfo"><!-- 获取异常变量 -->
<%
Integer.parseInt("keith");
%>
</c:catch>
${exinfo }<br/><!-- 输出异常变量 -->
<li>测试:redirect:直接跳转;context项目名称;url跳转的页面</li><br>
<c:redirect context="/struts_test" url="/index.jsp"/>
</body>