自定义标签库用的多么?

Question

各位，想问一下，自定义标签库用的多么?  一般什么时候需要用呢？刚学习web，希望大家能说的详细点，谢啦自定义标签库

Answer 1

自定义标签主要是写一次后，后期用的方便，如我们项目里的：
<app:select name="gcRegistMainDto" inputName="registReportorTpye" property="reportorTpye" styleClass="common" />
这是一个select 框的自定标签
<tag>
    <name>select</name>
    <tagclass>com.sinosoft.application.platform.web.taglib.SelectTag</tagclass>
    <bodycontent>JSP</bodycontent>
    <attribute>
      <name>inputName</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>codeType</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute> 
    <attribute>
      <name>withAll</name>
      <required>flase</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>withNull</name>
      <required>flase</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>withValue</name>
      <required>flase</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>hiddenCode</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
     <attribute>
      <name>orderStyle</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>    
    <attribute>
      <name>arg1</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>arg2</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>arg3</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>alt</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>altKey</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>disabled</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>indexed</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>multiple</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>name</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onblur</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onchange</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onclick</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>ondblclick</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onfocus</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onkeydown</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onkeypress</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onkeyup</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onmousedown</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onmousemove</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onmouseout</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onmouseover</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>onmouseup</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>property</name>
      <required>true</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>style</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>styleClass</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>styleId</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>tabindex</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>size</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>title</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>titleKey</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>value</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>hiddenArg</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
      <name>format</name>
      <required>false</required>
      <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>  
以上是标签的定义
<tagclass>com.sinosoft.application.platform.web.taglib.SelectTag</tagclass>

Answer 2

感觉了解即可，基本的struts标签，jstl标签都够用了。除非所在公司要求自定义标签

Answer 3

看情况了
一个项目中有很多不会改动的选择信息，我们就用自定义标签统一显示select