SpringMVC与Ajax的交互
ajax异步请求 javaScript and xml 异步请求
1、异步请求 特点：请求响应回来页面不动 只刷新页面局部
2、同步请求 特点：响应回来全部刷新(地址栏，超链接，表单 js的location.href="")
3、通过Ajax发送的请求都是异步请求 多请求之间并行处理 请求之间不会相互影响
Ajax发送请求 通过js的异步请求对象发送请求 xhr XMLHttpRequest
js实现ajax:
1、创建异步请求对象 xhr
2、准备并且发送请求xhr.open() xhr.send();
3、处理响应
xhr.onreadyStateChang=dunction(){
if(xhr.readyState==4&&xhr.status==200{
xhr.responseText
}
}
4、ajax只认字符串
jquery实现Ajax的封装
$.ajax({}) 基础发送Ajax请求的方式
$.get(url,method,function(){})//get方式发送请求
$.post(url,method,function{},"json")
控制器使用的json解析工具：阿里巴巴的fastjson
<!--引入阿里巴巴json解析器fastjson-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.73</version>
</dependency>
（1）交互示意图
（2）ajax页面
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
<%--引入js相关的jquery页面--%>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min.js"></script>
<script type="text/javascript">
$(function () {
//获取单击按钮对象，绑定单击事件
$("#btn").click(function () {
//发送get形式的Ajax异步请求
$.get("${pageContext.request.contextPath}/user/show", function (result) {
console.log(result)
}, "json");
})
});
</script>
</head>
<body>
<input type="button" value="点击查询所有" id="btn">
</body>
</html>
（3）实体类
public class User {
private Integer id;
private String Username;
private String password;
private Double salary;
private Date birthday;（4）Controller以手工转化json
@Controller
@RequestMapping("user")
public class QueryUser {
@RequestMapping("show")
public String showUser(HttpServletResponse response) throws IOException {
User user1 = new User(1,"王恒杰1","123",2000d,new Date());
User user2 = new User(2,"王恒杰2","123",20000d,new Date());
User user3 = new User(3,"王恒杰3","123",200000d,new Date());
User user4 = new User(4,"王恒杰4","123",2000000d,new Date());
User user5 = new User(5,"王恒杰5","123",20000000d,new Date());
List<User> users = Arrays.asList(user1, user2, user3, user4, user5);
//1、将users用户集合转化为json形式字符串
String jsonUsers = JSONObject.toJSONStringWithDateFormat(users, "yyyy-mm-dd");
//2、通过响应输出流，响应到客户端
//设置响应格式
response.setCharacterEncoding("utf-8");
response.getWriter().print(jsonUsers);
return null;
}
}
（5）响应到前端中文乱码 Ajax前端页面响应中文乱码
响应之前先设置响应格式：
//设置响应格式
response.setCharacterEncoding("utf-8");
解决乱码问题后
@responseBody:简化返回的数据转化成json串并且通过response响应的回客户端过程
@Controller
@RequestMapping("user")
public class QueryUser {
@RequestMapping("show")
@ResponseBody
public List<User> showUser(HttpServletResponse response) throws IOException {
User user1 = new User(1,"王恒杰1","123",2000d,new Date());
User user2 = new User(2,"王恒杰2","123",20000d,new Date());
User user3 = new User(3,"王恒杰3","123",200000d,new Date());
User user4 = new User(4,"王恒杰4","123",2000000d,new Date());
User user5 = new User(5,"王恒杰5","123",20000000d,new Date());
List<User> users = Arrays.asList(user1, user2, user3, user4, user5);
return users;
}
}
@ResponseBody替代示意图
（1）@responsBody注解 使用的json转化工具 不是fastjson,用的是jackjson
<!--jackson相关依赖 Springmvc@responsBody注解使用jackSon-->
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.11.3</version>
</dependency>
（2）@responsBody可以放在返回值前面
（3）设置当前方式的日期转化格式需要使用注解
//jackson SpringMVC内置的 @JsonFormat(pattern="yyyy-MM-dd HH:mm:ss",timezone = "GMT+8") //fastjson 阿里的 @JSONFiled(format="yyyy-mm-dd")
解决办法：在实体类的属性Date加入：@JsonFormat(pattern="yyyy-MM-dd HH:mm:ss",timezone = "GMT+8")
设置后结果：
（1）前端页面动态获取id，通过Ajax实现异步传输id值到Controller层
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.8.3.min.js"></script>
<script>
$(function () {
$("#del").click(function () {
$.get("${pageContext.request.contextPath}/user/showById?id=" + $("input[name='id']").val(), function (result) {
console.log(result);
// 创建ul标签
var ul = $("<ul></ul>");
// 创建li当前获取到的值
var idLi = $("<li>" + result.id + "</li>");
var usernameLi = $("<li>" + result.username + "</li>");
var passwordLi = $("<li>" + result.password + "</li>");
var salaryLi = $("<li>" + result.salary + "</li>");
var birthdayLi = $("<li>" + result.birthday + "</li>");
// 将li子标签添加到ul上
ul.append(idLi);
ul.append(usernameLi);
ul.append(passwordLi);
ul.append(salaryLi);
ul.append(birthdayLi);
$("#body").append(ul)
}, "json");
})
})
</script>
</head>
<body id="body">
ID：<input type="text" name="id" placeholder="请输入用户的ID">
<input type="button" name="id" value="提交" id="del">
</body>
</html>（2）控制层java代码
@RequestMapping("showById")
public @ResponseBody User showUserById(HttpServletResponse response,Integer id) throws IOException {
User user1 = new User(1,"王恒杰1","123",2000d,new Date());
User user2 = new User(2,"王恒杰2","123",20000d,new Date());
User user3 = new User(3,"王恒杰3","123",200000d,new Date());
User user4 = new User(4,"王恒杰4","123",2000000d,new Date());
User user5 = new User(5,"王恒杰5","123",20000000d,new Date());
List<User> users = Arrays.asList(user1, user2, user3, user4, user5);
for (User user : users) {
if(id.equals(user.getId())){
return user;
}
}
return null;
}
（3）效果展示图
