jsp2.0的tag，jsp自定义标签，类似jsp动态include

自定义标签好像现在已经很少使用

我们自定义的tag类需要继承TagSupport类，相应的方法返回值意义如下。

EVAL_BODY_INCLUDE：把Body读入存在的输出流中，doStartTag()函数可用
EVAL_PAGE：继续处理页面，doEndTag()函数可用
SKIP_BODY：忽略对Body的处理，doStartTag()和doAfterBody()函数可用
SKIP_PAGE：忽略对余下页面的处理，doEndTag()函数可用
EVAL_BODY_TAG：已经废止，由EVAL_BODY_BUFFERED取代
EVAL_BODY_BUFFERED：申请缓冲区，由setBodyContent()函数得到的BodyContent对象来处理tag的body，如果类实现了BodyTag，那么doStartTag()可用，否则非法

jsp 2.0提供一种新的用法“jsp tag”

只需要写XXX.tag文件，jsp页面中就可以引入

<%@ taglib prefix="tags" tagdir="/WEB-INF/tags/XXX.tag" %>

XXX.tag文件如下，这个tag文件实现的功能是：当前用户拥有权限时，才输出tag内部的html

  
    

   
     
    
      

     
       <%
     
       @ tag 
     
       import
     
       =
     
       "
     
       netid.right.util.SysrightUtil
     
       "
     
        
     
       %>
     
       

     
       <%
     
       @ tag 
     
       import
     
       =
     
       "
     
       netid.right.util.SysrightConstants
     
       "
     
        
     
       %>
     
       

     
       <%
     
       @ attribute name
     
       =
     
       "
     
       rightUrl
     
       "
     
        description
     
       =
     
       "
     
       rightUrl
     
       "
     
        
     
       %>
     
       

     
       <%
     
       

 String adminId 
     
       =
     
        SysrightUtil.getCookieInfo(request, SysrightConstants.RIGHT_USERID);
 String rights 
     
       =
     
        (String) SysrightConstants.RIGHT_MAP.get(adminId);
 
     
       if
     
        (rights 
     
       !=
     
        
     
       null
     
        
     
       &&
     
        rights.contains(rightUrl)) {

     
       %>
     
       

     
       <
     
       jsp:doBody
     
       />
     
       

     
       <%
     
       
 }

     
       %>
    
      


  
    





下面是抄自JSP 2.0 tag files 文档中的一段例子

原文http://www.softwaresummit.com/2005/speakers/BergmanJSP2.0TagFiles.pdf

example.tag:


  
    



   
     
    
      

     
       <%
     
       @ tag dynamic
     
       -
     
       attributes
     
       =
     
       "
     
       attrMap
     
       "
     
        body
     
       -
     
       content
     
       =
     
       "
     
       scriptless
     
       "
     
       %>
     
        

     
       <%
     
       @ attribute name
     
       =
     
       "
     
       bodyColor
     
       "
     
        required
     
       =
     
       "
     
       true
     
       "
     
       %>
     
        

     
       <%
     
       @ attribute name
     
       =
     
       "
     
       listopen
     
       "
     
        fragment
     
       =
     
       "
     
       true
     
       "
     
        required
     
       =
     
       "
     
       true
     
       "
     
       %>
     
        

     
       <%
     
       @ attribute name
     
       =
     
       "
     
       listitem
     
       "
     
        fragment
     
       =
     
       "
     
       true
     
       "
     
        required
     
       =
     
       "
     
       true
     
       "
     
       %>
     
        

     
       <%
     
       @ attribute name
     
       =
     
       "
     
       listclose
     
       "
     
        fragment
     
       =
     
       "
     
       true
     
       "
     
        required
     
       =
     
       "
     
       true
     
       "
     
       %>
     
        

     
       <%
     
       @ variable name
     
       -
     
       given
     
       =
     
       "
     
       aKey
     
       "
     
        scope
     
       =
     
       "
     
       NESTED%> 
     
       

     
       <%
     
       @ variable name
     
       -
     
       given
     
       =
     
       "
     
       aValue
     
       "
     
        scope
     
       =
     
       "
     
       NESTED%> 
     
       

     
       <%
     
       @ taglib prefix
     
       =
     
       "
     
       c
     
       "
     
        uri
     
       =
     
       "
     
       http://java.sun.com/jsp/jstl/core
     
       "
     
        
     
       %>
     
        

     
       <
     
       jsp:invoke fragment
     
       =
     
       "
     
       listopen
     
       "
     
        
     
       />
     
        

     
       <
     
       c:forEach var
     
       =
     
       "
     
       attr
     
       "
     
        items
     
       =
     
       "
     
       ${attrMap}
     
       "
     
       >
     
        
 
     
       <
     
       c:set var
     
       =
     
       "
     
       aKey
     
       "
     
        value
     
       =
     
       "
     
       ${attr.key}
     
       "
     
       />
     
        
 
     
       <
     
       c:set var
     
       =
     
       "
     
       aValue
     
       "
     
        value
     
       =
     
       "
     
       ${attr.value}
     
       "
     
       />
     
        
 
     
       <
     
       jsp:invoke fragment
     
       =
     
       "
     
       listitem
     
       "
     
       />
     
        

     
       </
     
       c:forEach
     
       >
     
        

     
       <
     
       jsp:invoke fragment
     
       =
     
       "
     
       listclose
     
       "
     
       />
     
        

     
       <
     
       FONT color
     
       =
     
       "
     
       ${bodyColor}
     
       "
     
       ><
     
       jsp:doBody
     
       /></
     
       FONT
     
       >
     
        
    
      


  
    

example.jsp：

   
     

    
      
     
       

      
         
      
        <%
      
        @ taglib prefix
      
        =
      
        "
      
        c
      
        "
      
         uri
      
        =
      
        "
      
        http://java.sun.com/jsp/jstl/core
      
        "
      
         
      
        %>
      
         
 
      
        <%
      
        @ taglib prefix
      
        =
      
        "
      
        my
      
        "
      
         tagdir
      
        =
      
        "
      
        /WEB-INF/tags/
      
        "
      
         
      
        %>
      
         
 
      
        <
      
        my:example bodyColor
      
        =
      
        "
      
        blue
      
        "
      
         first
      
        =
      
        "
      
        1
      
        "
      
         second
      
        =
      
        "
      
        2
      
        "
      
         third
      
        =
      
        "
      
        3
      
        "
      
         fourth
      
        =
      
        "
      
        4
      
        "
      
         fifth
      
        =
      
        "
      
        5
      
        "
      
         sixth
      
        =
      
        "
      
        6
      
        "
      
        >
      
         
 
      
        <
      
        jsp:attribute name
      
        =
      
        "
      
        listopen
      
        "
      
        >
      
         
 
      
        <
      
        table border
      
        =
      
        "
      
        1
      
        "
      
        >
      
         
 
      
        <
      
        caption
      
        >
      
        Dynamic Attributes
      
        </
      
        caption
      
        >
      
         
 
      
        <
      
        tr
      
        ><
      
        TH
      
        >
      
         Name
      
        </
      
        TH
      
        ><
      
        TH
      
        >
      
         Value
      
        </
      
        TH
      
        ></
      
        tr
      
        >
      
         
 
      
        </
      
        jsp:attribute
      
        >
      
         
 
      
        <
      
        jsp:attribute name
      
        =
      
        "
      
        listclose
      
        "
      
        >
      
         
 
      
        </
      
        table
      
        >
      
         
 
      
        </
      
        jsp:attribute
      
        >
      
         
 
      
        <
      
        jsp:attribute name
      
        =
      
        "
      
        listitem
      
        "
      
        >
      
         
 
      
        <
      
        tr
      
        >
      
         
 
      
        <
      
        td
      
        >
      
        ${aKey}
      
        </
      
        td
      
        >
      
         
 
      
        <
      
        td
      
        >
      
        ${aValue}
      
        </
      
        td
      
        >
      
         
 
      
        </
      
        tr
      
        >
      
         
 
      
        </
      
        jsp:attribute
      
        >
      
         
 
      
        <
      
        jsp:body
      
        >
      
        this
      
         is body text.
      
        </
      
        jsp:body
      
        >
      
         
 
      
        </
      
        my:example
      
        >