j-customtags-8-1.html

这是用java编写自定义标签的一些源码和笔记

  * 

  * @jsp.variable name-from-attribute="id"   class="java.util.Map"   

  *               scope="AT_BEGIN"

  */

 public class MapDefineTag extends TagSupport {

 

     public static final String FASTHASH = "FASTHASH";

     public static final String FASTTREE = "FASTTREE";

     public static final String HASH = "HASH";

     public static final String TREE = "TREE";

     private Map map = null;

     private String type = FASTTREE;

     private String id;

     private String scope;

 

     /* (non-Javadoc)

      * @see javax.servlet.jsp.tagext.Tag#doStartTag()

      */

     public int doStartTag() throws JspException {

 

         if (type.equalsIgnoreCase(FASTTREE)) {

             map = new FastTreeMap();

         } else if (type.equalsIgnoreCase(HASH)) {

           map = new HashMap();

         } else if (type.equalsIgnoreCase(TREE)) {

             map = new TreeMap();

         } else if (type.equalsIgnoreCase(FASTHASH)) {

             map = new FastHashMap();

         }

         

         if (scope == null){

             pageContext.setAttribute(id, map);

         }else if("page".equalsIgnoreCase(scope)){

             pageContext.setAttribute(id, map);

         }else if("request".equalsIgnoreCase(scope)){

             pageContext.getRequest().setAttribute(id, map);

         }else if("session".equalsIgnoreCase(scope)){

             pageContext.getSession().setAttribute(id, map);

         }else if("application".equalsIgnoreCase(scope)){

             pageContext.getServletContext().setAttribute(id, map);

         }

         

         return EVAL_BODY_INCLUDE;

     }

 

     /** Getter for property type.

      * @return Value of property type.

      * @jsp.attribute    

      *    required="false" 

      *    rtexprvalue="false"

      *    description="Specifies the type of map 

        *    valid values are fasttree, fasthash, hash, tree"

      */

     public String getType() {

         return type;

     }

 

     /**

      * @param string

      */

     public void setType(String string) {

         type = string;

     }

 

     /** Getter for property id.

      * @return Value of property id.

      * @jsp.attribute    required="true" 

      *                  rtexprvalue="false"

      *                  description="The id attribute"

      */

     public String getId() {

         return id;

     }

 

     /**

      * @param string

      */

     public void setId(String string) {

         id = string;

     }

     

     public Map getMap(){

         return map;

     }

 

     public void release() {

         super.release();

         map = null;

         type = FASTTREE;

     }

 

     /** Getter for property scope.

      * @return Value of property scope.

      * @jsp.attribute    required="false" 

      *                  rtexprvalue="false"

      *                  description="The scope attribute"

      */

     public String getScope() {

         return scope;

     }

 

     /**

      * @param string

      */

     public void setScope(String string) {

         scope = string;

     }

 

 }

 

 </code>
</pre>
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