AJAX Tag Library，包含一套JSP 标签，能够让你更简单的在jsp页面中使用Asynchronous JavaScript 和XML (AJAX) 技术。
标签库为比较通用的AJAX功能提供了5个标签：
autocomplete: retrieves a list of values that matches the string entered in a text form field as the user types
callout:displays a callout or popup balloon, anchored to an HTML element with an onclick event
Select/dropdown: based on a selection within a dropdown field, a second select field will be populated
toggle: switches a hidden form field between true and false and at the same time switches an image between two sources
update field: updates one or more form field values based on response to text entered in another field
autocomplete 标签的使用如下：在一个HTML form里，使用一个普通的input field:
<input id="model" name="model" type="text" autocomplete="off" size="30" class="form-autocomplete" />
然后，在jsp页面中，制定使用autocomplete 标签，并引用该input field:
popupId="model-popup"
targetId="make"
baseUrl="${contextPath}/autocomplete.view"
paramName="model"
className="autocomplete"
progressStyle="throbbing" />
autocomplete.view 请求将被转发到一个继承自BaseAjaxServlet的servlet, 这个servlet会返还预定格式的数据，这是一项标准的AJAX应用。
官方网站：http://ajaxtags.sourceforge.net/
标签：
