struts标签：logic标签

来源：互联网发布：eve捏脸数据编辑：程序博客网时间：2024/06/11 10:29

1.<logic:equal> and so on比较标签
以下eg都是由一个servlet转发过来的
 MyBean mb = new MyBean();
mb.setName("yc");
 mb.setCount(200);
 request.setAttribute("mybean",mb);
 request.getRequestDispatcher("jsp1.jsp").forward(request,response);

eg1：<bean:define id="myint" value="100"/> //当前页面定义一个字符串
 <logic:equal name="myint" value="100">
 myint=100
 </logic:equal>

eg2：<bean:define id="bean3" name="mybean" scope="request"/> //从request上获取bean
 <logic:lessThan name="bean3" property="count" value="200.a"> //比较bean的count属性和200.a
 bean3 LessThan 200.a
 </logic:lessThan>

注意：如果两个字符串都能够成功转为数字，则是比较数字的大小，否则像eg2就是比较字符串的大小

eg3：<bean:define id="bean1" name="mybean" property="name" scope="request"/>
 <logic:equal name="bean1" value="yc">
 name1=yc
 </logic:equal>

eg4：<bean:define id="bean2" name="mybean" scope="request"/>
 <logic:equal name="bean2" property="name" value="yc">
 name2=yc
 </logic:equal>

注意：eg3和eg4都是比较bean属性，只是写法不同

eg5：比较请求参数

<logic:equal parameter="id" value="150">
 <bean:parameter id="myid" name="id"/>
 parameter:<bean:write name="myid"/>=150
 </logic:equal>

2.<logic:match>
查看指定字符串是否被包含
<logic:match name="" value="被包含字符串" location="start/end也可以不写，就是任意位置"/>

eg：<bean:define id="bean4" name="mybean" property="name" scope="request"/>
 <logic:match name="bean4" value="y" location="start">
 yc is start with bean4
 </logic:match>

3.< logic:iterator>
a.遍历Vector等集合，value形式的
<logic:iterator id="每个集合的元素" name="集合在当前页面的绑定名" indexId="序号"
 offset="起始位置，0开始" length="遍历长度"/>

 前提： Vector v = new Vector();
 v.add("dog");
 v.add("girl");
 v.add("bird");
 v.add("cat");
 request.setAttribute("myvector",v);
 request.getRequestDispatcher("jsp1.jsp").forward(request,response);

eg1：<bean:define id="vector1" name="myvector" scope="request"/>
 <logic:iterate id="element" name="vector1">
 <bean:write name="element"/>
 
 </logic:iterate>

eg2：<bean:define id="vector2" name="myvector" scope="request"/>
 <logic:iterate id="element" name="vector2" indexId="index" offset="1" length="3">
 <bean:write name="index"/>.<bean:write name="element"/> 
 </logic:iterate>

b.遍历Map等，key/value形式
 只是输出的时候有所不同
 <bean:write name="" property="key"/>输出元素的key部分
 <bean:write name="" property="value"/>输出元素的value部分

前提： HashMap hm = new HashMap();
  hm.put("yc","yuechen");
  hm.put("tjs","tianjinsong");
  hm.put("xc","xiaocen");
  hm.put("xk","xukai");
  request.setAttribute("mymap",hm);

eg：<bean:define id="map1" name="mymap" scope="request"/>
 <logic:iterate id="element" name="map1" indexId="index">
 <bean:write name="index"/>.<bean:write name="element" property="key"/>:<bean:write name="element" property="value"/> 
 </logic:iterate>

c.遍历map中的集合
 双层iterator，内层iterator需要加入property="value"

  前提： HashMap hm2 = new HashMap();
               String[]asia = {"china","japan","korea"};
               hm2.put("asia",asia);
               String[]erop = {"greman","rasa","england"};
               hm2.put("erop",erop);
               String[]us = {"usa","canada"};
              hm2.put("us",us);
               request.setAttribute("country",hm2);

eg：<bean:define id="myc" name="country" scope="request"/>
 <logic:iterate id="element" name="country" indexId="index">
 <bean:write name="index"/>.<bean:write name="element" property="key"/> 
 <logic:iterate id="inelement" name="element" indexId="inindex" property="value">
 -----<bean:write name="inindex"/>.<bean:write name="inelement"/> 
 </logic:iterate>
 </logic:iterate>