AJAX
概念
Asynchronous JavaScript And XML :异步的JavaScript 和 XML
异步和同步：
Ajax是一种在无需重新加载整个网页的情况下，能够更新部分网页的技术，通过在后台与服务器进行少量的数据交换，Ajax可以使网页实现异步更新。这意味着可以不重新加载整个网页的情况下，对网页的某部分进行更新。传统的网页如果需要更新内容，必须重新加载整个网页页面。
实现方式
JQeury实现方式
| JQuery实现方式 | 语法 | 参数 |
| $.ajax() | $.ajax({键值对}) | url:请求路径，type:请求方式,data:post请求方式参数seccess：响应成功后的回调函数，error:表示如果请求响应出现错误，会执行的回调函数 |
| $.get() | $.get(url,[data],[callback],[type]) | url:请求路径，data:请求参数信息，callback:回调函数,type:响应结果类型 |
| $.post() | $.get(url,[data],[callback],[type]) | url:请求路径，data:请求参数信息，callback:回调函数,type:响应结果类型 |
$.ajax()
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script type="text/javascript" src="js/jquery-3.3.1.js"></script>
<script type="text/javascript" src="js/jquery-migrate-1.0.0.js"></script>
<script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
<script>
function f() {
//使用$.ajax()发送异步请求
$.ajax({
url:"ajaxServlet",//请求的路径
type:"POST",//请求方式
//data:"username=jack&age=23",//第一种方式：post请求方式携带的参数
data:{"username":"jack","age":23},
success:function (data) {
alert("data");
},//服务器响应成功后的回调函数
error:function () {
alert("出错啦");
}//表示如果出错后会执行的回调函数
})
}
</script>
</head>
<body>
<input type="button" value="发送异步请求" onclick="f();">
<input type="text">
</body>
</html>JSON
概念
语法
基本规则
获取数据
<script>
//1.定义基本格式
var person = {"name":"张三","age":23,"gender":true};
//获取name的值
//var name = person.name;
//var name2 = person["name"];
//2.嵌套格式{}---->[]
var persons = {
"persons":[
{"name":"张三","age":23,"gender":true},
{"name":"李四","age":23,"gender":true},
{"name":"王五","age":23,"gender":true}]
};
//获取王五对应的信息
// var name = persons["persons"][2].name;
//3.嵌套格式[] -----> {}
var ps = [{"name":"张三","age":23,"gender":true},
{"name":"李四","age":23,"gender":true},
{"name":"王五","age":23,"gender":true}];
//获取李四的信息
// var name = ps[1].name;
</script>遍历获取json对象及数组
<script>
var person = {"name":"张三","age":23,"gender":true};
var ps = [{"name":"张三","age":23,"gender":true},
{"name":"李四","age":23,"gender":true},
{"name":"王五","age":23,"gender":true}];
//获取person对象中的所有键和值
//key指的是键的名称,key默认是字符串，带有引号
for(var key in person){
alert(key+":"+person[key]);
}
//获取ps数组中的所有键和值
for (var i = 0; i < ps.length; i++) {
var p = ps[i];
for (var key in p){
alert(key +":"+p[key])
}
}
</script>Json数据和Java对象的相互转换
解析器
Java对象转换为JSON
package domain;
import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;
import java.util.Date;
public class Person {
private String name;
private int age;
private String gender;
// @JsonIgnore——方法1：忽略该属性
@JsonFormat(pattern = "yyyy-MM-dd")
private Date birthday;
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "Person{" + "name='" + name + '\'' + ", age=" + age + ", gender='" + gender + '\'' + '}';
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
}
public class jacksonTest2 {
@Test
public void test1() throws Exception {
//1.创建person对象
Person p = new Person();
p.setAge(34);
p.setGender("男");
p.setName("张三");
p.setBirthday(new Date());
//2.转换
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(p);
//生日格式为毫秒值，不友好
System.out.println(json);
}
}
List对象转换为Json
package Test;
import com.fasterxml.jackson.databind.ObjectMapper;
import domain.Person;
import org.junit.Test;
import java.io.File;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class jacksonTest3 {
//Java对象转为JSON字符串
@Test
public void test1() throws Exception {
//1.创建person对象
Person p = new Person();
p.setAge(34);
p.setGender("男");
p.setName("张三");
p.setBirthday(new Date());
Person p2 = new Person();
p2.setAge(34);
p2.setGender("男");
p2.setName("张三");
p2.setBirthday(new Date());
Person p3 = new Person();
p3.setAge(34);
p3.setGender("男");
p3.setName("张三");
p3.setBirthday(new Date());
//创建List集合
List<Person> ps = new ArrayList<Person>();
ps.add(p);
ps.add(p2);
ps.add(p3);
//转换
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(ps);
System.out.println(json);
//[{"name":"张三","age":34,"gender":"男","birthday":"2022-01-14"},{"name":"张三","age":34,"gender":"男","birthday":"2022-01-14"},{"name":"张三","age":34,"gender":"男","birthday":"2022-01-14"}]
}
}
Map对象转换为Json
public class jacksonTest4 {
//Java对象转为JSON字符串
@Test
public void test1() throws Exception {
//创建List集合
Map<String,Object> map = new HashMap<String,Object>();
map.put("name","张三");
map.put("age",34);
map.put("gender","男");
//转换
ObjectMapper mapper = new ObjectMapper();
String json = mapper.writeValueAsString(map);
System.out.println(json);
//{"gender":"男","name":"张三","age":34}
}
}JSON转换为Java对象
package Test;
import com.fasterxml.jackson.databind.ObjectMapper;
import domain.Person;
import org.junit.Test;
import java.util.HashMap;
import java.util.Map;
public class jacksonTest5 {
@Test
public void test1() throws Exception {
//初始化Json字符串
String json = "{\"gender\":\"男\",\"name\":\"张三\",\"age\":34}";
ObjectMapper mapper = new ObjectMapper();
Person person = mapper.readValue(json, Person.class);
System.out.println(person);
}
}
