{"id":81350,"date":"2020-09-02T09:00:49","date_gmt":"2020-09-02T03:30:49","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=81350"},"modified":"2021-08-25T13:47:19","modified_gmt":"2021-08-25T08:17:19","slug":"jsp-custom-tags","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/jsp-custom-tags\/","title":{"rendered":"JSP Custom Tags with Examples"},"content":{"rendered":"

This article consists of a detailed description of user-defined tags in JSP, better known as JSP custom tags. Their interfacing, advantages, detailed example has been discussed further in this article. So let’s learn the same.<\/p>\n

\"JSP<\/a><\/p>\n

JSP Custom Tags<\/h2>\n

JSP Custom tags are simply called user-defined tags. When a JSP is converted into a servlet, these tags get converted to a class. They are called tag handlers as they do action on an object. These actions get invoked by the web container at the time of execution of servlet.<\/p>\n

To create these tags, we need to extend and SimpleTagSupport, map TLD(Tag Library Descriptor), override doTag().<\/p>\n

These tags can be created so that the functionality of JSP can be extended. They allow the encapsulation of functionality. This is thus made available to non-expert page authors.<\/p>\n

Advantages of Custom Tags in JSP<\/h3>\n
    \n
  1. Portable \u2013<\/strong> Once declared in the Tag Library, these tags can be used anywhere.<\/li>\n
  2. Simple \u2013<\/strong> They are simple and convenient to use.<\/li>\n
  3. Expressive \u2013<\/strong> It provides a wide range of functionalities, scripting elements to the page authors.<\/li>\n
  4. Usable from different scripting languages \u2013<\/strong> This functionality can extend to other scripting languages.<\/li>\n
  5. No need for scriptlet tag –<\/strong> Once we create a custom tag, we don\u2019t need scriptlet tag. Though it is a bad approach in JSP.<\/li>\n
  6. Reusable –<\/strong> We can use the similar business logic over and over again.<\/li>\n
  7. Separation of business logic from JSP –<\/strong> For easy maintenance, Custom tags separate business logic and JSP.<\/li>\n<\/ol>\n

    Attributes of JSP Custom Tag<\/h3>\n\n\n\n\n\n\n\n\n\n
    S.No<\/strong>.<\/span><\/td>\nProperty<\/b><\/td>\nUse<\/b><\/td>\n<\/tr>\n
    1<\/span><\/td>\nname<\/b><\/td>\nThis attribute\u2019s purpose is to define the name of the tag. Each tag must have a unique name.<\/span><\/td>\n<\/tr>\n
    2<\/span><\/td>\nrequired<\/b><\/td>\nThis attribute will specify the requirement of the tag i.e., either required or optional.<\/span><\/td>\n<\/tr>\n
    3<\/span><\/td>\nrtexprvalue<\/b><\/td>\nThis attribute declares the runtime expression for the tag is valid or not.<\/span><\/td>\n<\/tr>\n
    4<\/span><\/td>\ntype<\/b><\/td>\nIt will define the class type of the attribute. By default, it will take it as a string.<\/span><\/td>\n<\/tr>\n
    5<\/span><\/td>\ndescription<\/b><\/td>\nThis attribute retrieves the description regarding information.\u00a0<\/span><\/td>\n<\/tr>\n
    6<\/span><\/td>\nfragment<\/b><\/td>\nIt specifies that the value this attribute holds will be a JspFragment or not.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Using Properties related to Attributes<\/h4>\n
    <attribute>\r\n  <name>attribute_name<\/name>\r\n<required>false<\/required>\r\n<type>java.util.Date<\/type>\r\n<fragment>false<\/fragment>\r\n<\/attribute>\r\n<\/pre>\n
    JSP Tag Interface<\/h3>\n