vjame

优化代码是无止境的
随笔 - 65, 文章 - 9, 评论 - 26, 引用 - 0
数据加载中……

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""<font color='red'>北京欢迎您</font>");
        
        
//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>
        
<br>
        
<hr>
        
<li>
            测试c:out
        
</li>
        
<br>
        hello(default):
        
<c:out value="${hello}"></c:out>
        
<br>
        hello(default=123):
        
<c:out value="${hello}" default="123"></c:out>
        
<br>
        
<!-- value值为空或者null时,取default的默认值 -->
        hello(default=123):
        
<c:out value="${hello1}">123</c:out>
        
<br>

        bj(default):
        
<c:out value="${bj}"></c:out>
        
<br>
        bj(escapeXml="true"):
        
<c:out value="${bj}" escapeXml="true"></c:out>
        
<br>
        
<!-- 解析xml格式的数据 -->
        bj(escapeXml="false"):
        
<c:out value="${bj}" escapeXml="false"></c:out>
        
<br>
        
<p>
        
<li>
            测试c:set和c:remove
        
</li>
        
<br>
        
<c:set value="123" var="temp"></c:set>
        temp:${temp }
        
<br>
        
<c:remove var="temp" />
        temp:${temp }
        
<br>

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

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

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

        
<p>
        
<li>
            测试循环控制标签c:forEach
        
</li>
        
<br>
        
<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>

        
<p>
        
<li>
            测试循环控制标签c:forEach,varstatus
        
</li>
        
<br>
        
<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>
        
        
<p>
    
<li>测试循环控制标签c:forEach,普通循环</li><br>
    
<c:forEach begin="1" end="10">
        a
<br>
    
</c:forEach>
    
    
<p>
    
<li>测试循环控制标签c:forEach,输出map</li><br>
    
<c:forEach  items="${mapvalue}" var="v">
        ${v.key }=${v.value }
<br>
    
</c:forEach>
    
    
    
<p>
    
<li>测试循环控制标签c:forTokens</li><br>
    
<c:forTokens items="${strTokens}" delims="," var="v">
        ${v }
<br>
    
</c:forTokens>
    
    
    
<p>
    
<li>测试c:catch</li><br>
    
<%
        try {
            
Integer.parseInt("asdfsdf");
        }catch(Exception e) {
            out.println(e.getMessage());
        }    
    
%>
    
<p>
    
<c:catch var="exinfo">
        
<%
            
Integer.parseInt("asdfsdf");
        
%>
    
</c:catch>
    ${exinfo }
<br>
    
    
<p>
    
<li>测试c:import</li><br>
    
<!-- 引入外部url地址 -->
    
<c:import url="http://localhost:8080/struts_login"/>
    
<p>
    
<li>测试c:url和c:param</li><br>
    
<!-- 给url后面加参数 -->
    
<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 }
<br>


    
        
    
</body>
</html>

posted on 2009-07-27 10:39 lanjh 阅读(442) 评论(0)  编辑  收藏 所属分类: Java Web


只有注册用户登录后才能发表评论。


网站导航: