<input type="hidden" id="classpath" value="${pageContext.request.contextPath }"/>

         <div id="div">

             <form id="userForm">

                <span>搜索用户：<input type="text" id="text_input" name="userName" value=""/> 输入后自动搜索</span>

            </form>

            <div id="usersdiv">

                <ul>

                </ul>

            </div>

           </div>

//点击text事件

      $(function(){

          function text_input_sousuo(){

              var classpath = $("#classpath").val();

              var userName = $("#text_input").val();

              var usersdiv = $("#usersdiv ul");

              var text = "";

              //ajax

             $.ajax({

                type:"Post",

                data:{"userName":userName},//传入的参数

                dataType:"json",//接收回来是数组

                url:classpath+"/getUserByAllJson",

                 success:function(data){

                    $.each(data.users,function(i){

                        text+="<li>"+data.users[i].userName+"</li>";

                     });

                     usersdiv.html(text);

                     var usersli = $("#usersdiv ul li");

                        usersli.css({"float":"left","border":"1px solid #cccccc","height":"28px",

                            "width":"60px","margin":"10px","background-color":"#efefef","cursor":"pointer"

                        });

                    usersli.on("click",function(){

                        $("#text_input").val($(this).html());

                        usersdiv.empty();

                    });

                }

            });

          };

          $("#text_input").on("keyup",function(){

              text_input_sousuo();

          });

          $("#text_input").on("focus",function(){

              text_input_sousuo();

         }); 

<package name="users" extends="json-default" namespace="/">

        <action name="getUserByAllJson" method="getUserByAll" class="cn.bdqn.action.user.UserAction">

            <result type="json">

                <param name="includeProperties">users.*</param>

            </result>

        </action>

    </package>

$("button").click(function(){

  $.getJSON("demo_ajax_json.js",function(result){

    $.each(result, function(i, field){

      $("div").append(field + " ");

    });

  });

});

<package name="users" extends="json-default" namespace="/">

        <action name="getUserByAllJson" method="getUserByAll" class="cn.bdqn.action.user.UserAction">

            <result type="json">

                <param name="root">users</param>

            </result>

        </action>

    </package>