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笔记-JavaWeb学习之旅18

程序员文章站 2022-12-24 16:08:08
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);
    }

}

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