jstl标签库(1)

jstl标签库的配置
* 将jstl.jar和standard.jar拷贝到WEB-INF/lib下（如果使用el表达式，不用拷贝这两个jar）

注意：jstl必须在能够支持j2ee1.4/servlet2.4/jsp2.0版本上的容器才能运行，这个环境
是目前较为常用的环境

标签库的使用
* 采用taglib指令引入
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%>

jstl核心库(core)

Action

package com.lanjh.struts.action;

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.lanjh.struts.po.Group;
import com.lanjh.struts.po.User;

public class JstlCoreAction extends Action {

 @Override
 public ActionForward execute(ActionMapping mapping, ActionForm form,
 HttpServletRequest request, HttpServletResponse response)
 throws Exception {
 request.setAttribute( " hello " , " hello world " );

 // html文本
 request.setAttribute( " bj " , " 北京欢迎您 " );

 // 测试条件控制标签
 request.setAttribute( " v1 " , 1 );
 request.setAttribute( " v2 " , 2 );
 request.setAttribute( " v3 " , new ArrayList());
 request.setAttribute( " v4 " , " test " );


 // 测试c:forEach
 Group group = new Group();
 group.setName( " 尚学堂 " );

 List userList = new ArrayList();
 for ( int i = 0 ; i < 10 ; i ++ ) {
 User user = new User();
 user.setUsername( " user_ " + i);
 user.setAge( 18 + i);
 user.setGroup(group);
 userList.add(user);
 }

 request.setAttribute( " userlist " , userList);

 // 测试循环输出map
 Map < String, String > map = new HashMap < String, String > ();
 map.put( " k1 " , " lanjh " );
 map.put( " k2 " , " chenj " );
 request.setAttribute( " mapvalue " , map);

 // 测试c:forTokens
 request.setAttribute( " strTokens " , " 1,2,3,4,5,6 " );


 return mapping.findForward( " success " );
 }

}

struts配置

< action path ="/jstlcore"
 type ="com.lanjh.struts.action.JstlCoreAction" >
 < forward name ="success" path ="/jstl_core.jsp" ></ forward >
 </ action >

JSP页面

<% @ page language = " java " import = " java.util.* " pageEncoding = " utf-8 " %>
<% @ taglib prefix = " c " uri = " http://java.sun.com/jsp/jstl/core " %>

<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" >
< html >
 < head >
 < title > 测试jstl核心库 </ title >
 </ head >
 < body >
 < h1 >
 测试EL表达式
 </ h1 >
 
 < hr >
 < li >
 测试c:out
 </ li >
 
 hello(default):
 < c:out value ="${hello}" ></ c:out >
 
 hello(default=123):
 < c:out value ="${hello}" default ="123" ></ c:out >
 
 
 hello(default=123):
 < c:out value ="${hello1}" > 123 </ c:out >
 

 bj(default):
 < c:out value ="${bj}" ></ c:out >
 
 bj(escapeXml="true"):
 < c:out value ="${bj}" escapeXml ="true" ></ c:out >
 
 
 bj(escapeXml="false"):
 < c:out value ="${bj}" escapeXml ="false" ></ c:out >
 
 
 < li >
 测试c:set和c:remove
 </ li >
 
 < c:set value ="123" var ="temp" ></ c:set >
 temp:${temp }
 
 < c:remove var ="temp" />
 temp:${temp }
 

 
 < li >
 测试条件控制标签c:if
 </ li >
 
 < c:if test ="${v1 lt v2}" var ="v" >
 v1小于v2 
 v=${v }
 </ c:if >
 < c:if test ="${empty v3}" >
 v3为空 
 </ c:if >
 < c:if test ="${!empty v4}" >
 v4不为空 
 </ c:if >

 
 < li >
 测试条件控制标签c:choose,c:when,c:otherwise
 </ li >
 

 < c:choose >
 < c:when test ="${v1 lt v2}" >
 v1小于v2 
 </ c:when >
 < c:otherwise >
 v1大于v2 
 </ c:otherwise >
 </ c:choose >

 < c:choose >
 < c:when test ="${empty v4}" >
 v4为空 
 </ c:when >
 < c:otherwise >
 v4不为空 
 </ c:otherwise >
 </ c:choose >

 
 < li >
 测试循环控制标签c:forEach
 </ li >
 
 < table border ="1" >
 < tr >
 < td >
 姓名
 </ td >
 < td >
 年龄
 </ td >
 < td >
 所属组
 </ 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 ="u" >
 < tr >
 < td >
 ${u.username }
 </ td >
 < td >
 ${u.age }
 </ td >
 < td >
 ${u.group.name }
 </ td >
 </ tr >
 </ c:forEach >
 </ c:otherwise >

 </ c:choose >
 </ table >

 
 < li >
 测试循环控制标签c:forEach,varstatus
 </ li >
 
 < table border ="1" >
 < tr >
 < td >
 姓名
 </ td >
 < td >
 年龄
 </ td >
 < td >
 所属组
 </ 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 ="${vs.count % 2 == 0}" >
 < tr bgcolor ="red" >
 </ c:when >
 < c:otherwise >
 < tr >
 </ c:otherwise >
 </ c:choose >
 < td >
 < c:out value ="${user.username}" />
 </ td >
 < td >
 < c:out value ="${user.age}" />
 </ td >
 < td >
 < c:out value ="${user.group.name}" />
 </ td >
 </ tr >
 </ c:forEach >
 </ c:otherwise >
 </ c:choose >
 </ table >

 
 < li > 测试循环控制标签c:forEach，普通循环 </ li > 
 < c:forEach begin ="1" end ="10" >
 a 
 </ c:forEach >

 
 < li > 测试循环控制标签c:forEach，输出map </ li > 
 < c:forEach items ="${mapvalue}" var ="v" >
 ${v.key }=${v.value } 
 </ c:forEach >


 
 < li > 测试循环控制标签c:forTokens </ li > 
 < c:forTokens items ="${strTokens}" delims ="," var ="v" >
 ${v } 
 </ c:forTokens >


 
 < li > 测试c:catch </ li > 
 <%
 try {
 Integer .parseInt( " asdfsdf " );
 }catch(Exception e) {
 out.println(e.getMessage());
 }
 %>
 
 < c:catch var ="exinfo" >
 <%
 Integer .parseInt( " asdfsdf " );
 %>
 </ c:catch >
 ${exinfo } 

 
 < li > 测试c:import </ li > 
 
 < c:import url ="http://localhost:8080/struts_login" />
 
 < li > 测试c:url和c:param </ li > 
 
 < c:url value ="http://localhost:8080/drp/sysmgr/user_add.jsp" var ="v" >
 < c:param name ="username" value ="Jack" />
 < c:param name ="age" value ="20" />
 </ c:url >
 ${v } 



 </ body >
</ html >

jstl标签库(1)

jstl标签库(1)

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