ajax应用
一、异步校验用户名是否存在
1.需求：
用户名是否存在.png
2.代码：
JQ代码：
<script type="text/javascript">
$(function(){
//为输入框绑定事件
$("#username").blur(function(){
//1、失去焦点获得输入框的内容
var usernameInput = $(this).val();
//2、去服务端校验该用户名是否存在---ajax
$.post(
"${pageContext.request.contextPath}/checkUsername",
{"username":usernameInput},
function(data){
var isExist = data.isExist;
//3、根据返回的isExist动态的显示信息
var usernameInfo = "";
if(isExist){
//该用户存在
usernameInfo = "该用户名已经存在";
$("#usernameInfo").css("color","red");
}else{
usernameInfo = "该用户可以使用"
$("#usernameInfo").css("color","green");
}
$("#usernameInfo").html(usernameInfo);
},
"json"
);
});
});
</script>
HTML代码：
<label for="username" class="col-sm-2 control-label">用户名</label>
<div class="col-sm-6">
<input type="text" class="form-control" id="username"
placeholder="请输入用户名">
<span id="usernameInfo"></span>
</div>
服务端代码：
public class CheckUsernameServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获得要校验的用户名
String username = request.getParameter("username");
//传递username到service
UserService service = new UserService();
boolean isExist = false;
try {
isExist = service.checkUsername(username);
} catch (SQLException e) {
e.printStackTrace();
}
response.getWriter().write("{\"isExist\":"+isExist+"}");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
二、站内搜索
JS代码：
<!-- 完成异步搜索 -->
<script type="text/javascript">
function overFn(obj){
$(obj).css("background","#DBEAF9");
}
function outFn(obj){
$(obj).css("background","#fff");
}
function clickFn(obj){
$("#search").val($(obj).html());
$("#showDiv").css("display","none");
}
function searchWord(obj){
//1、获得输入框的输入的内容
var word = $(obj).val();
//2、根据输入框的内容去数据库中模糊查询---List<Product>
var content = "";
$.post(
"${pageContext.request.contextPath}/searchWord",
{"word":word},
function(data){
//3、将返回的商品的名称 显示在showDiv中
//[{"pid":"1","pname":"小米 4c 官方版","market_price":8999.0,"shop_price":8999.0,"pimage":"products/1/c_0033.jpg","pdate":"2016-08-14","is_hot":1,"pdesc":"小米 4c 标准版 全网通 白色 移动联通电信4G手机 双卡双待 官方好好","pflag":0,"cid":"1"}]
if(data.length>0){
for(var i=0;i<data.length;i++){
content+="<div style='padding:5px;cursor:pointer' onclick='clickFn(this)' onmouseover='overFn(this)' onmouseout='outFn(this)'>"+data[i]+"</div>";
}
$("#showDiv").html(content);
$("#showDiv").css("display","block");
}
},
"json"
);
}
</script>
HTML代码：
<form class="navbar-form navbar-right" role="search">
<div class="form-group" style="position:relative">
<input id="search" type="text" class="form-control" placeholder="Search" onkeyup="searchWord(this)">
<div id="showDiv" style="display:none; position:absolute;z-index:1000;background:#fff; width:179px;border:1px solid #ccc;">
</div>
</div>
<button type="submit" class="btn btn-default">Submit</button>
</form>
服务端代码：
public class SearchWordServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获得关键字
String word = request.getParameter("word");
//查询该关键字的所有商品
ProductService service = new ProductService();
List<Object> productList = null;
try {
productList = service.findProductByWord(word);
} catch (SQLException e) {
e.printStackTrace();
}
//["xiaomi","huawei",""...]
//使用json的转换工具将对象或集合转成json格式的字符串
/*JSONArray fromObject = JSONArray.fromObject(productList);
String string = fromObject.toString();
System.out.println(string);*/
Gson gson = new Gson();
String json = gson.toJson(productList);
System.out.println(json);
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write(json);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}