json 对象字符串格式

什么是json
    .json
    .xml
    数据库访问

JSON:一种与开发语言无关的、轻量级的数据存储格式，全称JavaScript Object Notation，一种数据格式的标准规范，起初来源于JavaScript这门语言，后来随着使用的广泛，几乎每门开发语言都有处理JSON的API。

优点：易于人的阅读和编写，易于程序解析与生产。

JSON样例：首先一个花括号{}，整个代表一个对象，同时里面是一种Key-Value的存储形式，它还有不同的数据类型来区分
 

实例：

package com.zking.aa;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSON;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Test {
	public static void main(String[] args) throws Exception {
		//JSON：对象字符串
		//如果在java代码中需要将一个对象字符串转换成一个对象
		//需要用到第三方插件
		
		/**
		 * 
		 * JSON的格式
		 * 
		 * {
		 * 
		 * 		"name":"嘿嘿嘿",
		 * 		"name":"嘿嘿嘿",
		 * 
		 * }
		 * 
		 * 
		 * 
		 * [
		 * 		{
		 * 			"name":"嘿嘿嘿",
		 * 			"name":"嘿嘿嘿",
		 * 		}
		 * ]
		 * 
		 * 
		 * 
		 */
		
		
		//1.fastJSON
		//（1）导包
		
		//实例化一个hmj
//		hmj h = new hmj("湖名居","男",19);
		System.out.println(h.toString());
//		
//		//将ds转换成一个满足json定义格式的字符串
		{"age":19,"hname":"湖名居","hsex":"男"}
//		String jsonString = JSON.toJSONString(h);
//		System.out.println(jsonString);
//		
//		String h2 = "{\"age\":19,\"hname\":\"湖名居\",\"hsex\":\"男\"}";
//		hmj h3 = JSON.parseObject(h2, hmj.class);
//		System.out.println(h3.getHname());
		
		
		//2.jackJSON
		hmj h = new hmj("湖名居","男",19);
		//实例化一个json格式转换对象
		ObjectMapper mapper = new ObjectMapper();
		String writeValueAsString = mapper.writeValueAsString(h);
		System.out.println(writeValueAsString);
		
		List list = new ArrayList();
		for (int i = 0; i < 5; i++) {
			list.add(new hmj("hhh"+i,"男",18+i));
		}
		String writeValueAsString2 = mapper.writeValueAsString(h);
		System.out.println(writeValueAsString2);
		
		System.out.println("```````````````````````````````````````````");
		
		Map maps = new HashMap<>();
		for (int i = 0; i < 5; i++) {
			maps.put("湖名居"+i, new hmj("hhh"+i,"男",18+i));
		}
		
		String h2 = "{\"age\":19,\"hname\":\"湖名居\",\"hsex\":\"男\"}";
		hmj readValue = mapper.readValue(h2.getBytes(), hmj.class);
		System.out.println(readValue.getHname());
		
		
		
		
		
	}
}

实体类

package com.zking.aa;
/**
 * 实体
 * @author 
 *
 * 2022年4月24日下午2:26:25
 */
public class hmj {
	
	private String hname;
	private String hsex;
	private Integer age;
	
	public hmj() {
		// TODO Auto-generated constructor stub
	}

	public String getHname() {
		return hname;
	}

	public void setHname(String hname) {
		this.hname = hname;
	}

	public String getHsex() {
		return hsex;
	}

	public void setHsex(String hsex) {
		this.hsex = hsex;
	}

	public Integer getAge() {
		return age;
	}

	public void setAge(Integer age) {
		this.age = age;
	}

	public hmj(String hname, String hsex, Integer age) {
		this.hname = hname;
		this.hsex = hsex;
		this.age = age;
	}

	@Override
	public String toString() {
		return "hmj [hname=" + hname + ", hsex=" + hsex + ", age=" + age + "]";
	}
	
	
	
	
	
}