JavaWeb_Ajax通过JQuery和原生js异步传输数据

　　菜鸟教程　　传送门

　　AJAX 优点：在不重新加载整个页面的情况下，可以与服务器交换数据并更新部分网页内容

　　XMLHttpRequest 对象　　传送门

　　（一） [JQuery]定时发送ajax请求

　　（二） [JQuery]发送ajax时客户端服务端进行数据传递

　　（三） [原生JS]使用原生js代码完成ajax请求

　　（四）通过Ajax检测用户注册信息重复

[JQuery]定时发送ajax请求　　JQuery.ajax()文档

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Insert title here</title>

<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-3.3.1.min.js"></script>

<script type="text/javascript">

//2000ms调用一次这个方法

setInterval("callAjax()",2000);

function callAjax(){

    $.ajax({

//         alert("ajax");ajaxrequest

        url:"${pageContext.request.contextPath }/ajaxrequest",

        cache:false,    //去除缓存

        type:"get",

        success:function(msg){

            //将数据刷新到页面上

            $("#msg").append(msg);

        }

    });

}

</script>

</head>

<body>

<form action="${pageContext.request.contextPath}/login_do" method="post">

用户名：<input type="text" name="username" /><br/>

密码：<input type="password" name="password" /><br/>

<input type="submit" value="登录" />

</form>

<div id ="msg"></div>

</body>

</html>

ajax.jsp

package com.Gary.controller;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/ajaxrequest")

public class AjaxServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //System.out.println("发送ajax请求");

        response.setContentType("text/html; charset=utf-8");

        response.getWriter().append("ajax数据");

    }

}

AjaxServlet.java

　　客户端发送get请求由AjaxServlet.java中doGet去接收

[JQuery]发送ajax时客户端服务端进行数据传递

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Insert title here</title>

<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-3.3.1.min.js"></script>

<script type="text/javascript">

//2000ms调用一次这个方法

setInterval("callAjax()",2000);

function callAjax(){

    $.ajax({

//         alert("ajax");ajaxrequest

//        发送中文需要对中文做一个编码使用encodeURI()

        url:encodeURI("${pageContext.request.contextPath }/ajaxrequest?data=我是客户端发送过来的数据"),

        cache:false,    //去除缓存

        type:"get",

        success:function(msg){

            //将数据刷新到页面上

            $("#msg").append(msg);

        }

    });

}

</script>

</head>

<body>

<form action="${pageContext.request.contextPath}/login_do" method="post">

用户名：<input type="text" name="username" /><br/>

密码：<input type="password" name="password" /><br/>

<input type="submit" value="登录" />

</form>

<div id ="msg"></div>

</body>

</html>

ajax.jsp

package com.Gary.controller;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/ajaxrequest")

public class AjaxServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //System.out.println("发送ajax请求");

        System.out.println("收到了ajax请求："+request.getParameter("data"));

        response.setContentType("text/html; charset=utf-8");

        response.getWriter().append("ajax数据");

    }

}

AjaxServlet.java

　　中文编码处理时使用encodeURI()方法

　　服务端数据的交互也通过AjaxServlet.java中的doGet去接收

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //System.out.println("发送ajax请求");

        System.out.println("收到了ajax请求："+request.getParameter("data"));

        response.setContentType("text/html; charset=utf-8");

        response.getWriter().append("ajax数据");

    }

【原生js】使用原生js代码完成ajax请求

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Insert title here</title>

<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-3.3.1.min.js"></script>

<script type="text/javascript">

//2000ms调用一次这个方法

setInterval("callAjax()",2000);

function callAjax(){

    //alert("123123");

    var xmlhttp = new XMLHttpRequest();

    //xmlHttp.open("post", url, true);    第三个：是否是异步请求    加随机数去处理缓存

    xmlhttp.open("GET",encodeURI("${pageContext.request.contextPath }/ajaxrequest?data=我是客户端发送的数据&"+Math.random()),true);

    xmlhttp.send();

    xmlhttp.onreadystatechange = function(){

        if(xmlhttp.readyState==4 && xmlhttp.status==200){

            //得到了服务器端的响应

            $("#msg").append(xmlhttp.responseText);

        }

    }

}

</script>

</head>

<body>

<form action="${pageContext.request.contextPath}/login_do" method="post">

用户名：<input type="text" name="username" /><br/>

密码：<input type="password" name="password" /><br/>

<input type="submit" value="登录" />

</form>

<div id ="msg"></div>

</body>

</html>

ajax.jsp

package com.Gary.controller;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/ajaxrequest")

public class AjaxServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //System.out.println("发送ajax请求");

        System.out.println("收到了ajax请求："+request.getParameter("data"));

        response.setContentType("text/html; charset=utf-8");

        response.getWriter().append("ajax数据");

    }

}

AjaxServlet.java

setInterval("callAjax()",2000);

function callAjax(){

    //alert("123123");

    var xmlhttp = new XMLHttpRequest();

    //xmlHttp.open("post", url, true);    第三个：是否是异步请求    加随机数去处理缓存

    xmlhttp.open("GET",encodeURI("${pageContext.request.contextPath }/ajaxrequest?data=我是客户端发送的数据&"+Math.random()),true);

    xmlhttp.send();

    xmlhttp.onreadystatechange = function(){

        if(xmlhttp.readyState==4 && xmlhttp.status==200){

            //得到了服务器端的响应

            $("#msg").append(xmlhttp.responseText);

        }

    }

}

通过Ajax检测用户注册信息重复

<%@ page language="java" contentType="text/html; charset=utf-8"

    pageEncoding="utf-8"%>

<!DOCTYPE html>

<html>

<head>

<meta charset="utf-8">

<title>Insert title here</title>

<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-3.3.1.min.js"></script>

<script type="text/javascript">

//     当网页加载完后会调用这个函数

    $(function(){

//         当username失去焦点的时候执行

        $("input[name='username']").blur(verifyUsername);

    });

    function verifyUsername(){

//         $("input[name='username']").val()

        $.ajax({

            url:encodeURI("${pageContext.request.contextPath }/verifyUsername"),

            type:"post",

            data:{

//                 验证用户名是否存在

                username:$("input[name='username']").val()

            },

            cache:false,

            dataType:"json",

            success:function(msg){

                //alert(msg.isSuccess);

                if(msg.isSuccess){

                    alert("用户名可以用!");

                }else{

                    alert("用户名重复!");

                }

            }

        });

    }

</script>

</head>

<body>

<%

if(request.getAttribute("msg")!=null)

    out.println(request.getAttribute("msg")+"<br/>");

%>

注册

<hr/>

<form action="<%=request.getContextPath() %>/register_do" method="post">

用户名：<input type="text" name="username" /><br/>

密码：<input type="password" name="password" /><br/>

年龄：<input type="text" name="age" /><br/>

性别： 男<input type="radio" name="sex" value="男" checked="checked"/>女<input type="radio" name="sex" value="女" /><br/>

<input type="submit" value="注册" />

</form>

</body>

</html>

package com.Gary.service;

import com.Gary.dao.UserDao;

import com.Gary.model.User;

public class UserService {

    //处理注册请求

    public boolean register(String username,String password,int age ,String sex) {

        UserDao userDao = new UserDao();

        boolean isExist =userDao.isExist(username);

        if(isExist)

            return false;

        else

            userDao.addUser(username, password, age, sex);

        return true;

    }

    public User login(String username,String password) {

        return new UserDao().getUserByUP(username, password);

    }

    public boolean isExist(String username) {

        return new UserDao().isExist(username);

    }

}

UserService.java

package com.Gary.controller;

import java.io.IOException;

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 com.Gary.service.UserService;

@WebServlet("/verifyUsername")

public class VerifyUsernameServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String username = request.getParameter("username");

        UserService service = new UserService();

        boolean isExist = service.isExist(username);

        response.getWriter().append("{\"isSuccess\":"+!isExist+"}");

    }

}

VerityUsernameServlet.java

　　其他页面代码(MVC)管理员后台商品查询demo

　　通过Ajax异步请求在鼠标离焦username标签时将请求发送至verifyUsername并自动校验数据库中用户ID

<script type="text/javascript">

//     当网页加载完后会调用这个函数

    $(function(){

//         当username失去焦点的时候执行

        $("input[name='username']").blur(verifyUsername);

    });

    function verifyUsername(){

//         $("input[name='username']").val()

        $.ajax({

            url:encodeURI("${pageContext.request.contextPath }/verifyUsername"),

            type:"post",

            data:{

//                 验证用户名是否存在

                username:$("input[name='username']").val()

            },

            cache:false,

            dataType:"json",

            success:function(msg){

                //alert(msg.isSuccess);

                if(msg.isSuccess){

                    alert("用户名可以用!");

                }else{

                    alert("用户名重复!");

                }

            }

        });

    }

</script>

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        String username = request.getParameter("username");

        UserService service = new UserService();

        //service.isExist()判断有无重复用户ID

        boolean isExist = service.isExist(username);

        //有的话返回false表示不允许用户注册，反之为true

        response.getWriter().append("{\"isSuccess\":"+!isExist+"}");

    }

　　设置当Ajax异步校验成功返回msg类型时使用dataType:"xxx"并在doPost中的isSuccess使用" "引号引起来

　　中文编码处理时使用encodeURI()方法

巴特西

JavaWeb_Ajax通过JQuery和原生js异步传输数据

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