struts标签使用举例--logic篇

<logic:iterate id="course" name="courseList" >
          <tr><td colspan="2"> <input type="checkbox" name="courseId" value="${course.id }" />${course.name }</td></tr>
          </logic:iterate>

1.  logic:empty
          该标签是用来判断是否为空的。如果为空，该标签体中嵌入的内容就会被处理。该标签用于以下情况：

         1）当Java对象为null时；
         2）当String对象为""时；
         3）当java.util.Collection对象中的isEmpty()返回true时；
         4）当java.util.Map对象中的isEmpty()返回true时。
          eg.
            <logic:empty   name="userList"> 
              ... 
           </logic:empty>
           该句等同于：
           if   (userList.isEmpty())   { 
                 ... 
           }
   2.  logic:notEmpty
          该标签的应用正好和logic:empty标签相反，略。
   3. logic:equal
      该标签为等于比较符。
      eg1. 比较用户的状态属性是否1，若为1，输出"启用";
          <logic:equal   name="user"   property="state"   value="1">
          启用
         </logic:equal>
     eg2. 如果上例中的value值是动态获得的，例如需要通过bean:write输出，因struts不支持标签嵌套，可采用EL来解决该问题。
          <logic:equal   name="charge"   property="num"   value="${business.num}"> 
                    ......
         </logic:equal>
    4. logic:notEqual
          该标签意义与logic:equal相反，使用方法类似，略。
    5. logic:forward
          该标签用于实现页面导向，查找配置文件的全局forward。
          eg. <logic:forward name="index"/>
    6. logic:greaterEqual
          为大于等于比较符。
          eg. 当某学生的成绩大于等于90时，输出“优秀”：
               <logic:greaterEqual name="student" property="score" value="90">
                  优秀
            </logic:greaterEqual>
    7. logic:greaterThan
          此为大于比较符，使用方法同logic:greaterEqual，略;
    8. logic:lessEqual
          此为小于等于比较符，使用方法同logic:greaterEqual,略;
    9. logic:lessThan
          此为小于比较符，使用方法同logic:greaterEqual,略;
    10. logic:match
          此标签比较对象是否相等；
          eg1. 检查在request范围内的name属性是否包含"amigo"串：
            <logic:match name="name" scope="request" value="amigo">
                  <bean:write name="name"/>中有一个“amigo”串。
            </logic:match>
         eg2. 检查在request范围内的name属性是否已“amigo”作为起始字符串：
           <logic:match name="name" scope="request" value="amigo" location="start">
               <bean:write name="name"/>以“amigo”作为起始字符串。
            </logic:match>
         eg3.
            <logic:match header="user-agent" value="Windows">
               你运行的是Windows系统
            </logic:match>
    11.  logic:notMatch

          此标签用于比较对象是否不相同，与logic:match意义相反，使用方法类似，略。
     12. logic:messagePresent
          该标签用于判断ActionMessages/ActionErrors对象是否存在；
          eg. 如果存在error信息，将其全部输出：
               <logic:messagePresent property="error">
                  <html:messages property="error" id="errMsg" >
                        <bean:write name="errMsg"/>
                  </html:messages> 
               </logic:messagePresent >
     13. logic:messagesNotPresent
          该标签用于判断ActionMessages/ActionErrors对象是否不存在,使用方法与logic:messagePresent类似，略
      14. logic:present
           此标签用于判断request对象传递参数是否存在。
           eg1. user对象和它的name属性在request中都存在时，输出相应字符串：
              <logic:present name="user" property="name">
                  user对象和该对象的name属性都存在
            </logic:present>
          eg2. 若有一个名字为“user”的JavaBean，输出对应字符串：
             <logic:present name="user" >
                  有一个名字为“user”的JavaBean。
            </logic:present>
          eg3.
            <logic:present header="user-agent">
                  we got a user-agent header.
            </logic:present>
      15. logic:notPresent
           此标签用于判断request对象传递参数是否不存在，意义与了logic:present相反，使用方法类似，略。
      16. logic:redirect
           该标签用于实现页面转向，可传递参数。
           eg1. <logic:redirect href="http://www.chinaitlab.com"/>
     
       17. logic:iterator
            用于显示列表为collection的值（List ,ArrayList,HashMap等）。
            eg1. 逐一输出用户列表(userlList)中用户的姓名：
               <logic:iterate  id="user" name="userList">
                  <bean:write name="user" property="name"/><br>
               </logic:iterate>
            eg2. 从用户列表中输出从1开始的两个用户的姓名
               <logic:iterate  id="user" name="userList" indexId="index"  offset="1" length="2">
                  <bean:write name="index"/>.<bean:write name="user" property="name"/><br>
               </logic:iterate>
            eg3. logic:iterator标签的嵌套举例
                <logic:iterate id="user" indexId="index" name="userList">
                       <bean:write name="index"/>. <bean:write name="user" property="name"/><br>
                       <logic:iterate id="address" name="user" property="addressList" length="3" offset="1">
                           <bean:write name="address"/><br>
                       </logic:iterate>
               </logic:iterate>


第六次学习:

1.逻辑判断标签:
代码



  定义一些变量

<jsp:useBean id="bean" scope="page" class="org.apache.struts.webapp.exercise.TestBean" /><%

              String bool1 = "true";

              String bool2 = "false";

              String str1 = "This is a string";

              String str2 = "Less than";

              String str3 = "XYZ greater than";

            %>

  相等

<logic:equal name="bean" property="booleanProperty" value="<%= bool1 %>">equal</logic:equal>

  不等

<logic:notEqual name="bean" property="booleanProperty" value="<%= bool1 %>">notEqual</logic:notEqual>

大于等于
<logic:greaterEqual name
="bean" property="stringProperty" value="<%= str1 %>">greaterEqual</logic:greaterEqual>

    大于

<logic:greaterThan name="bean" property="stringProperty" value="<%= str1 %>">greaterThan</logic:greaterThan>

    小于等于       

  <logic:lessEqual name="bean" property="stringProperty" value="<%= str1 %>">lessEqual</logic:lessEqual>

    小于      

   <logic:lessThan name="bean" property="stringProperty" value="<%= str1 %>">lessThan</logic:lessThan>

    不等       

  <logic:notEqual name="bean" property="stringProperty" value="<%= str1 %>">notEqual</logic:notEqual>


2.逻辑判断标签(数值):

代码



  定义变量

<jsp:useBean id="bean" scope="page" class="org.apache.struts.webapp.exercise.TestBean" /><%

      String doub1 = "321.0";

      String doub2 = "111.0";

      String doub3 = "333.0";

      String long1 = "321";

      String long2 = "111";

      String long3 = "333";

      String short1 = "987";

      String short2 = "654";

      String short3 = "999";

    %>

      等于

  <logic:equal name="bean" property="doubleProperty" value="<%= doub2 %>">equal</logic:equal>

      大于等于

   <logic:greaterEqual name="bean" property="doubleProperty" value="<%= doub2 %>">greaterEqual</logic:greaterEqual>

      大于

    <logic:greaterThan name="bean" property="doubleProperty" value="<%= doub2 %>">greaterThan</logic:greaterThan>

    小于等于      

   <logic:lessEqual name="bean" property="doubleProperty" value="<%= doub2 %>">lessEqual</logic:lessEqual>

    小于      

   <logic:lessThan name="bean" property="doubleProperty" value="<%= doub2 %>">lessThan</logic:lessThan>

    不等于     

   <logic:notEqual name="bean" property="doubleProperty" value="<%= doub2 %>">notEqual</logic:notEqual>

2.逻辑判断是否为空:
代码

<jsp:useBean id="bean" scope="page" class="org.apache.struts.webapp.exercise.TestBean" />

    <table border="1">

      <tr>

        <th>Test Type</th>

        <th>Correct Value</th>

        <th>Test Result</th>

      </tr>

      <tr>

        <td>missing bean, no property attribute</td>

        <td>empty</td>

        <td>

          <logic:empty name="missingBean">empty</logic:empty>

          <logic:notEmpty name="missingBean">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>not-missing bean, no property attribute</td>

        <td>notEmpty</td>

        <td>

          <logic:empty name="bean">empty</logic:empty>

          <logic:notEmpty name="bean">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>null</td>

        <td>empty</td>

        <td>

          <logic:empty name="bean" property="nullProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="nullProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>empty string</td>

        <td>empty</td>

        <td>

          <logic:empty name="bean" property="emptyStringProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="emptyStringProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>non-empty string</td>

        <td>notEmpty</td>

        <td>

          <logic:empty name="bean" property="stringProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="stringProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>empty collection</td>

        <td>empty</td>

        <td>

          <logic:empty name="bean" property="emptyListProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="emptyListProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>non-empty collection</td>

        <td>notEmpty</td>

        <td>

          <logic:empty name="bean" property="listProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="listProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>empty map</td>

        <td>empty</td>

        <td>

          <logic:empty name="bean" property="emptyMapProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="emptyMapProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>non-empty map</td>

        <td>notEmpty</td>

        <td>

          <logic:empty name="bean" property="mapProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="mapProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

      <tr>

        <td>unsupported object</td>

        <td>notEmpty</td>

        <td>

          <logic:empty name="bean" property="intProperty">empty</logic:empty>

          <logic:notEmpty name="bean" property="intProperty">notEmpty</logic:notEmpty>

        </td>

      </tr>

    </table>

评论

1 楼 mulangren1988 2011-03-07  

很详细啊