jstl_core

一. 

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"%> 
 

  1<h1>测试jstl核心库</h1>
  2    <hr>
  3    <li>测试c:out</li><br>
  4    hello(default):<c:out value="${hello}"/><br>
  5    hello(el表达式):${hello }<br>
  6    hello(default="123"):<c:out value="${abc}" default="123"/><br>
  7    hello(default="123"):<c:out value="${abc}">123</c:out><br>
  8    bj(defalut):<c:out value="${bj}"/><br>
  9    bj(escapeXml="true"):<c:out value="${bj}" escapeXml="true"/><br>
 10    bj(escapeXml="false"):<c:out value="${bj}" escapeXml="false"/><br>
 11    bj(el表达式):${bj }<br>
 12    <p>
 13    <li>测试c:set和c:remove</li><br>
 14    <c:set value="123" var="temp"/>
 15    temp:${temp }<br>
 16    <c:remove var="temp"/>
 17    temp:${temp }<br>
 18    <p>
 19    <li>测试条件控制标签c:if</li><br>
 20    <c:if test="${v1 lt v2}" var="v">
 21        v1小于v2<br>v=${v }<br>
 22    </c:if>
 23    <c:if test="${empty v3}">
 24        v3为空<br>
 25    </c:if>
 26    <c:if test="${empty v4}">
 27        v4为空<br>
 28    </c:if>
 29    <p>
 30    <li>测试条件控制标签c:choose,c:when,c:otherwise</li><br>
 31    <c:choose>
 32        <c:when test="${v1 lt v2}">
 33            v1小于v2<br>
 34        </c:when>
 35        <c:otherwise>
 36            v1大于v2<br>
 37        </c:otherwise>
 38    </c:choose>
 39    <c:choose>
 40        <c:when test="${empty v4}">
 41            v4为空<br>
 42        </c:when>
 43        <c:otherwise>
 44            v4不为空<br>
 45        </c:otherwise>
 46    </c:choose>
 47    <p>
 48    <li>测试循环控制标签c:forEach</li><br>
 49    <table border="1">
 50        <tr>
 51            <td>姓名</td>
 52            <td>年龄</td>
 53            <td>所属组</td>
 54        </tr>
 55        <c:choose>
 56            <c:when test="${empty userlist}">
 57                <tr>
 58                    <td colspan="3">没有符合条件的数据!</td>
 59                </tr>
 60            </c:when>
 61            <c:otherwise>
 62                <c:forEach items="${userlist}" var="u">
 63                    <tr>
 64                        <td>${u.username }</td>
 65                        <td>${u.age }</td>
 66                        <td>${u.group.name }</td>
 67                    </tr>
 68                </c:forEach>
 69            </c:otherwise>
 70        </c:choose>
 71    </table>    
 72    <p>    
 73    <li>测试循环控制标签c:forEach,varstatus</li><br>
 74    <table border="1">
 75        <tr>
 76            <td>姓名</td>
 77            <td>年龄</td>
 78            <td>所属组</td>
 79        </tr>
 80        <c:choose>
 81            <c:when test="${empty userlist}">
 82                <tr>
 83                    <td colspan="3">没有符合条件的数据!</td>
 84                </tr>
 85            </c:when>
 86            <c:otherwise>
 87                <c:forEach items="${userlist}" var="user" varStatus="vs">
 88                    <c:choose>
 89                        <c:when test="${vs.count % 2 == 0}">
 90                            <tr bgcolor="red">
 91                        </c:when>
 92                        <c:otherwise>
 93                            <tr>
 94                        </c:otherwise>
 95                    </c:choose>
 96                                <td>
 97                                    <c:out value="${user.username}"/>
 98                                </td>
 99                                <td>
100                                    <c:out value="${user.age}"/>
101                                </td>
102                                <td>
103                                    <c:out value="${user.group.name}"/>
104                                </td>
105                            </tr>                    
106                </c:forEach>
107            </c:otherwise>
108        </c:choose>
109    </table>
110    <p>
111    <li>测试循环控制标签c:forEach,begin,end,step</li><br>
112    <table border="1">
113        <tr>
114            <td>姓名</td>
115            <td>年龄</td>
116            <td>所属组</td>
117        </tr>
118        <c:choose>
119            <c:when test="${empty userlist}">
120                <tr>
121                    <td colspan="3">没有符合条件的数据!</td>
122                </tr>
123            </c:when>
124            <c:otherwise>
125                <c:forEach items="${userlist}" var="user" begin="2" end="8" step="2">
126                    <tr>
127                        <td>${user.username}</td>
128                        <td>${user.age}</td>
129                        <td>${user.group.name }</td>
130                    </tr>
131                </c:forEach>
132            </c:otherwise>
133        </c:choose>
134    </table>    
135    <p>
136    <li>测试循环控制标签c:forEach，普通循环</li><br>
137    <c:forEach begin="1" end="10">
138        a<br>
139    </c:forEach>
140    <p>
141    <li>测试循环控制标签c:forEach，输出map</li><br>
142    <c:forEach  items="${mapvalue}" var="v">
143        ${v.key }=${v.value }<br>
144    </c:forEach>
145    <p>
146    <li>测试循环控制标签c:forTokens</li><br>
147    <c:forTokens items="${strTokens}" delims="," var="v">
148        ${v }<br>
149    </c:forTokens>
150    <p>
151    <li>测试c:catch</li><br>
152    <%
153        try {
154            Integer.parseInt("asdfsdf");
155        }catch(Exception e) {
156            out.println(e.getMessage());
157        }    
158    %>
159    <p>
160    <c:catch var="exinfo">
161        <%
162            Integer.parseInt("asdfsdf");
163        %>
164    </c:catch>
165    ${exinfo }<br>
166    <p>
167    <li>测试c:import</li><br>
168    <c:import url="http://localhost:8080/struts_login"/>
169    <p>
170    <li>测试c:url和c:param</li><br>
171    <c:url value="http://localhost:8080/drp/sysmgr/user_add.jsp" var="v">
172        <c:param name="username" value="Jack"/>
173        <c:param name="age" value="20"/>
174    </c:url>
175    ${v }<br>
176    <li>测试:redirect</li><br>
177    <c:redirect context="/struts_login" url="/index.jsp"/>