User name verification during registration
Check and analysis of user name registration
(1) Write the html form of the jsp page
(2) Write jquery request
(3) Processing servlet response
web\register.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
<title>Title</title>
<%-- 2 导入js编写发送请求的代码 --%>
<%-- <script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-3.3.1.js"></script>--%>
<script type="text/javascript" src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
//页面加载成功
//获取输入框
$("#username").on("blur",function () {
//获取输入的账号
//alert($("#username").val())
// 3 发送请求
$.ajax({
url:"queryUsername",
async:true,
data:"username="+$("#username").val(),
type:"post",
dataType:"json",
success:function (data) {
//{"msg":"恭喜，该邮件地址可以注册","code":0}
// alert(data.code)
//alert(data.msg)
//5：根据服务端返回的json数据，编写显示逻辑
if(data.code == 0){
$("#msg").text(data.msg)
$("#msg").css("color","green")
}else{
$("#msg").text(data.msg)
$("#msg").css("color","red")
}
},
error:function () {
alert("服务器发生了错误")
}
});
})
})
</script>
</head>
<body>
<!-- 1 显示表单 -->
<form method="post" action="${pageContext.request.contextPath}/register">
username: <input id="username" name="username" type="text"><br/>
<div id="msg" style="color: green;"></div>
password: <input name="passowrd" type="password"><br/>
<input type="submit" value="注册"><br/>
</form>
</body>
</html>
(3) Write servlet
- (1) What is returned is json data
- (2) The object is converted into json data
src\com\wzx\servlet\QueryServlet.java
//4:编写后台业务逻辑
@WebServlet("/queryUsername")
public class QueryServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1:接收请求获取参数
String username = request.getParameter("username");
//2:处理业务逻辑
Result result = new Result();
if("jack".equals(username)){
//3:都需要是json数据
result.setMsg("该邮箱地址已被注册");
result.setCode(1);
//返回已注册
}else{
result.setMsg("恭喜，该邮件地址可以注册");
result.setCode(0);
//返回未注册
}
response.setContentType("text/html;charset=utf-8");
response.getWriter().println(new ObjectMapper().writeValueAsString(result));
}
}
src\com\wzx\servlet\Result.java
public class Result {
private String msg;
private int code;
public Result(String msg, int code) {
this.msg = msg;
this.code = code;
}
public Result() {
}
//..
}