Json数据对象——java操作

╰+攻爆jí腚メ 2022-05-14 05:26 202阅读 0赞

Json是一种**轻量级**的用于**数据传输**语言。

基本格式：

{key:value}

[源码与jar包已上传github上][jar_github]

**       1、java对象 => json 对象 => String（json）       **

**       2、java List=>json 数组对象=>String(json)**

**       3、String(json)=>json对象=>java对象**

**       4、String(json)=> json对象=>java 对象数组**

//BootMain.java
    
    package com.cc.yonyou.funOne;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import com.cc.yonyou.People;
    
    import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    public class BootMain {
    	
    	public static void main(String[] args){
    		String[] school = {"小学","初中","高中"};
    		People p = new People();
    		p.setName("Tom");
    		p.setAge(20);
    		p.setSchool(school);
    		System.out.println("--------------json对象-----------");
    		JSONObject jsonObj = JSONObject.fromObject(p);
    		System.out.println(jsonObj.toString());
    		
    		System.out.println("--------------json数组-----------");
    
    		People p1 = new People();
    		p1.setName("Jack");
    		p1.setAge(22);
    		p1.setSchool(school);
    		List<People> list = new ArrayList<People>();
    		list.add(p);
    		list.add(p1);
    		//2、json数组
    		JSONArray jsonListAry = JSONArray.fromObject(list);
    		System.out.println(jsonListAry.toString());
    		
    		
    		//字符串转对象
    		String objStr = "{'school':['小学','初中','高中'],'name':'Tom','age':20}";
    		String objList = "[{'school':['小学','初中','高中'],'name':'Tom','age':20},{'school':['小学','初中','高中'],'name':'Jack','age':22}]";
    
    		System.out.println("--------------java对象---------------");
    		JSONObject strObj=JSONObject.fromObject(objStr);
    		People p2 = (People) JSONObject.toBean(strObj,People.class);
    		System.out.println(p2.getName());
    		
    		System.out.println("--------------java List对象---------------");
    		JSONArray listObj=JSONArray.fromObject(objList);
    		People[] pList = (People[]) JSONArray.toArray(listObj,People.class);
    		System.out.println(pList[1].getName());
    	}
    }

输出结果：

--------------json对象-----------
    {"school":["小学","初中","高中"],"name":"Tom","age":20}
    --------------json数组-----------
    [{"school":["小学","初中","高中"],"name":"Tom","age":20},{"school":["小学","初中","高中"],"name":"Jack","age":22}]
    --------------java对象---------------
    Tom
    --------------java List对象---------------
    Jack

【注】：jar包导入![70][]

**在api开发中，会将对象封装到一个BaseJSON：**

// BaseJSON.java
    package com.cc.yonyou.funTwo; 
    
    public class BaseJSON {
    	protected int code = 0;
    	protected Object result;
    	
    	public BaseJSON(){
    	}
    
    	
    	public int getCode() {
    		return code;
    	}
    
    
    	public void setCode(int code) {
    		this.code = code;
    	}
    
    
    	public Object getResult() {
    		return result;
    	}
    
    	public void setResult(Object result) {
    		this.result = result;
    	}
    
    
    	@Override
    	public String toString() {
    		return "BaseJSON [code=" + code + ", result=" + result + "]";
    	}
    
    
    }

//BootMain.java
    
    package com.cc.yonyou.funTwo;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import com.cc.yonyou.People;
    
    
    public class BootMain {
    	public static void main(String[] args){
    
    		String[] school = {"小学","初中","高中"};
    		People p = new People();
    		p.setAge(20);
    		p.setSchool(school);
    		People p1 = new People();
    		p1.setName("Jack");
    		p1.setAge(22);
    		p1.setSchool(school);
    		List<People> list = new ArrayList<People>();
    		list.add(p);
    		list.add(p1);
    		
    		BaseJSON json = new BaseJSON();
    		json.setResult(list);
    		System.out.println(json.toString());
    	}
    	
    }

输出：

BaseJSON [code=0, result=[com.cc.yonyou.People@15db9742, com.cc.yonyou.People@6d06d69c]]

**在JavaWeb中，传递json，使用gson，下载gson.jar**

//BootMain.java
    
    package com.cc.yonyou.funThree;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import com.cc.yonyou.People;
    import com.google.gson.Gson;
    
    public class BootMain {
    	public static void main(String[] args){
    		String[] school = {"小学","初中","高中"};
    		People p = new People();
    		p.setAge(20);
    		p.setSchool(school);
    		People p1 = new People();
    		p1.setName("Jack");
    		p1.setAge(22);
    		p1.setSchool(school);
    		List<People> list = new ArrayList<People>();
    		list.add(p);
    		list.add(p1);
    		
    		Gson gson = new Gson();
    		String json = gson.toJson(list);
    		System.out.println(json);
    	}
    }

输出：

[{"age":20,"school":["小学","初中","高中"]},{"name":"Jack","age":22,"school":["小学","初中","高中"]}]

[jar_github]: https://github.com/2637977081/java/tree/master/JSON
[70]: /images/20220514/38f9c164c848442f871f13a86b7796f7.png