笔记-JavaWeb学习之旅18
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2022-04-28 16:43:45
AJAX:ASynchronous JavaScript And XML 异步的JavaScript 和XML 异步和同步：客户端和服务器端相互通信的基础上 同步：客户端操作后必须等待服务器端的响应，在等待的期间客户端不能做其他操作 异步：客户端操作后，不需要等待服务器端的响应，在服务器处理请求的过 ......
ajax:asynchronous javascript and xml 异步的javascript 和xml
异步和同步：客户端和服务器端相互通信的基础上
同步：客户端操作后必须等待服务器端的响应，在等待的期间客户端不能做其他操作
异步：客户端操作后，不需要等待服务器端的响应，在服务器处理请求的过程中，客户端可以进行其他的操作
jquery对ajax实现
实现异步的方式
使用$.ajax()发送异步请求
<!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
$.get(url,[data],[callback],[type])
url:请求路径
data:请求参数
callback:回调函数，载入成功后执行的函数
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])
json:
1.概念：javascript object notation javascript对象表示法
json现在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
把java对象转换为json对象
注解：@jsonignore:排除不需要的属性，@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);
//创建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):该方法有很多重载方法
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());
//创建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);
}
}