异步和同步：客户端和服务器端相互通讯的基础上javascript
同步：客户端操做后必须等待服务器端的响应，在等待的期间客户端不能作其余操做html
异步：客户端操做后，不须要等待服务器端的响应，在服务器处理请求的过程当中，客户端能够进行其余的操做java
JQuery对AJAX实现jquery
使用$.ajax()发送异步请求ajax
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
//定义方法
function fun(){
//使用JQuery的方式实现异步请求
$.ajax({
url:"ajaxServlet1",//必选参数
type:"POST",//请求方式，可选参数
data:{"username":"jack","age":23},//请求参数，可选
success:function(data){
alert(data);//data变量是服务器响应给会的结果值
},//响应成功后的回调函数,可选
error:function(){
alert("出错啦...");
},//请求响应出现错误，会执行的回调函数
dataType:"text"//设置接受到的响应数据的格式
});
}
</script>
</head>
<body>
<input type="button" value="发送异步请求" onclick="fun();">
<input>
</body>
</html>
package com.data.ajax;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/ajaxServlet1")
public class AjaxServlet1 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取请求参数
String username = request.getParameter("username");
String age = request.getParameter("age");
System.out.println(username);
//响应请求请求
response.getWriter().write("hello :" + username+age);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
使用$.get()和$.post()发送异步请求json
$.get(url,[data],[callback],[type])数组
url:请求路径服务器
data:请求参数app
callback:回调函数，载入成功后执行的函数dom
type:响应结果的类型
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script src="js/jquery-3.3.1.min.js"></script>
<script>
function fun() {
$.get("ajaxServlet1",{"username":"zhangsan"},function (data) {
alert(data)
})
}
</script>
</head>
<body>
<input type="button" value="发送异步请求" onclick="fun();">
<input>
</body>
</html>
$.post(url,[data],[callback],[type])
1.概念：JavaScript Object Notation JavaScript对象表示法
json如今多用于存储和交换文本信息的语法
进行数据的传输
JSON比XML更小，更快，更易解析
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
var person1={"name":"张三",age:23,'gender':"true"};
//遍历对象
for(key in person1){
alert(key+":"+person1[key]);
}
//获取name的值
var name1 = person1.name;
alert(name1)
//嵌套格式{}->[]
var person2 = {
"person":[
{"name":"张三","age":23,"gender":true},
{"name":"李四","age":24,"gender":true},
{"name":"王五","age":25,"gender":false},
]
};
//嵌套格式 []-{}
var person3=[
{"name":"张三","age":23,"gender":true},
{"name":"李四","age":24,"gender":true},
{"name":"王五","age":25,"gender":false},
]
alert("===============")
//遍历数组person3
for(var i=0;i<person3.length;i++){
var l=person3[i];
for(key in l ){
alert(key+l[key]);
}
}
</script>
</head>
<body>
</body>
</html>
JSON解释器--jackson
常见JSON解释器：Jsonlib,Gson,fastjson,jackson
注解：@JsonIgnore:排除不须要的属性，@JsonFormat:属性值格式化
复杂java对象转换
1.List:转换出来的是数组
3.Map:转换出来结果与对象格式一致
package com.data.domain;
import com.fasterxml.jackson.annotation.JsonFormat;
import java.util.Date;
public class Person {
private String name;
private String gender;
private int age;
@JsonFormat(pattern = "yyyy-MM-dd")//设置指定格式
private Date birthday;
public Person(String name, String gender, int age, Date birthday) {
this.name = name;
this.gender = gender;
this.age = age;
this.birthday = birthday;
}
public Person(String name, String gender, int age) {
this.name = name;
this.gender = gender;
this.age = age;
}
public Person() {
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", gender='" + gender + '\'' +
", age=" + age +
", birthday=" + birthday +
'}';
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
}
package com.data.test;
import com.data.domain.Person;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Test;
import java.io.File;
import java.util.*;
public class TestDemo1 {
//把Java对象转化为JSON对象
@Test
public void test1() throws Exception {
Person person = new Person("张三","男",20);
//建立Jackson的核心对象，ObjectMapper
ObjectMapper mapper = new ObjectMapper();
/*
writeValueAsString(obj):将对象转为json字符串
转换方法：writeValue(参数1,obj):该方法有不少重载方法
参数1：
File:将obj对象转换为JSON字符串，并保存到指定的文件中
Writer:将Obj对象转换为JSON字符串，并将json数据填充到字符输出流中
OutputStream:将obj对象转换为JSON字符串，并将json数据填充到字节输出流中
*/
String s = mapper.writeValueAsString(person);
System.out.println(s);//{"name":"张三","gender":"男","age":20}
//将JSON写入文件
mapper.writeValue(new File("e://a.txt"),person);
}
@Test
public void test2() throws Exception {
Person person = new Person("张三","男",20, new Date());
ObjectMapper mapper = new ObjectMapper();
String s = mapper.writeValueAsString(person);
System.out.println(s);
}
//List集合转JSON对象
@Test
public void test3() throws Exception {
Person person1 = new Person("张三","男",20, new Date());
Person person2 = new Person("李四","女",22, new Date());
Person person3 = new Person("王五","男",23, new Date());
Person person4 = new Person("赵六","女",24, new Date());
//建立List集合
List<Person> list = new ArrayList<>();
list.add(person1);
list.add(person2);
list.add(person3);
list.add(person4);
//把List集合转换为JSON对象
ObjectMapper mapper = new ObjectMapper();
String s = mapper.writeValueAsString(list);
System.out.println(s);
}
@Test
public void test5() throws Exception {
Map<String,Object> map = new HashMap<>();
map.put("name","张三");
map.put("age",22);
map.put("gender","男");
ObjectMapper mapper = new ObjectMapper();
String s = mapper.writeValueAsString(map);
System.out.println(s);
}
//把JSON对象转换为java对象
@Test
public void test6() throws Exception {
//初始化JSON字符串
String json = "{\"gender\":\"男\",\"name\":\"张三\",\"age\":22}";
ObjectMapper mapper = new ObjectMapper();
Person s = mapper.readValue(json,Person.class);
System.out.println(s);
}
}