jsp注册页面，Ajax实现验证用户名是否存在，密码是否一致，当不存在时，注册按钮变成灰色。

旧城等待， 2022-06-10 00:10 201阅读 0赞

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
    <title>注册页面</title>
    <script type="text/javascript">
        function createXMLHttpRequest() { //创建XMLHttpRequest
            try {
                return new XMLHttpRequest(); //直接创建对象，不适用与IE5,IE6
            } catch (e) {
                try {
                    return new ActiveXObject("Msxml2.XMLHTTP");//对于不适用的，创建合适的对象
                } catch (e) {
                    return new ActiveXObject("Microsoft.XMLHTTP");
                }
            }
        }
    function send() {
    var xmlHttp = createXMLHttpRequest();
    
    xmlHttp.onreadystatechange = function () {
        if (xmlHttp.readyState === 4 && xmlHttp.status == 200) { //判断xmlHttp的状态是否完毕
            if(xmlHttp.responseText == "true") { 
            //判断ajax从Servlet中返回的信息，即判断用户名是否存在。
                document.getElementById("Username_Error_Massage").innerHTML=    
                "<font color='red'>用户名已被注册！</font>"; 
                //弹出警告信息，告知不可适用该用户名
            document.all("register").disabled=true; 　//将注册按钮关闭，无法点击
            }else {
                document.getElementById("Username_Error_Massage").innerHTML = "账号可用!";
                document.all("register").disabled=false;　//开启注册按钮
            }
        }
    };
        var method = "POST"; //定义传输方式
        var url="/Taobei/registerServlet?" + new Date().getTime(); 　
        //定义对应的URL，为了避免浏览器的缓存造成干扰，加上时间戳
        xmlHttp.open(method, url, true);
        xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        var username = document.getElementById("username").value;
        if(username===undefined || username === null || username === ""){
            //判断用户名是否为空
            alert("账号不能为空！"); // 弹出警告信息
        }
        xmlHttp.send("username=" + username); //发送信息
       }
    function inspect_password() { //判断两次用户名是否一致，不一致时，注册按钮不可使用
    if(document.getElementById("password01").value !=
    document.getElementById("password02").value){
    document.getElementById("div_password").innerHTML
    = "<font color='red'>两次密码不一致</font>"
    document.all("register").disabled=true;
    }else {
    document.getElementById("div_password").innerHTML
    = "密码一致！"
    document.all("register").disabled=false;
    }
    }
    </script>
    </head>
    <body>
    <h1>欢迎来到注册页面</h1>
    <hr>
    <form action="/registerServlet" method="post">
    账号：<input type="text" name="username" id="username" onblur="send()"/>
    <span id="Username_Error_Massage"></span>
    <br/>
    
    密码：<input type="password" name="password" id="password01"/>
    <br/>
    重复密码:<input type="password" name="password_repeat" id="password02" onblur="inspect_password()"/>
    <span id="div_password"></span>
    <br/>
    
    邮箱：<input type="email" name="email"/><br/>
    <input type="submit" value="提交" name="register"/>
    </form>
    </body>
    </html>
     
    registerServlet的代码如下：

package Servlet;
    
    import javax.management.Query;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    /**
     * Created by user on 17-7-20. * This Servlet suppport register page.
     */
    @WebServlet(name = "registerServlet", value = "/registerServlet")
    public class registerServlet 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 {
            String username = request.getParameter("username");
            if (username.equals("test")) { //单纯测试，不进行连接数据库，，相同返回true 
                response.getWriter().print(true);
            } else {
                //不同返回false; 
                response.getWriter().print(false);
            }
        }
    }  
    // 最后结果如下：