【JSON解析】浅谈JSONObject的使用

朴灿烈づ我的快乐病毒、 2023-05-29 09:28 16阅读 0赞

### 简介 ###

在程序开发过程中，在参数传递，函数返回值等方面，越来越多的使用JSON。JSON(JavaScript Object Notation)是一种轻量级的数据交换格式，同时也易于机器解析和生成、易于理解、阅读和撰写，而且Json采用完全独立于语言的文本格式，这使得Json成为理想的数据交换语言。   
JSON建构于两种结构：

“名称/值”对的集合(A Collection of name/value pairs)，在不同的语言中，它被理解为对象(Object), 记录(record), 结构(struct), 字典(dictionary), 有趣列表(keyed list), 哈希表(hash table)或者关联数组(associative array)。

**JSONObject依赖：**

最后一行需要保留，有两个jdk版本的实现：json-lib-2.1-jdk13.jar和json-lib-2.1-jdk15.jar

**使用net.sf.json需要导入的jar包**

![20191105182121613.png][]

jar包下载：[https://pan.baidu.com/s/1iZiXw55TPwIxYFQQCaR9Gw][https_pan.baidu.com_s_1iZiXw55TPwIxYFQQCaR9Gw]

# JSONObject #

创建JSONObject，添加属性

//创建JSONObject
    JSONObject json = new JSONObject();
    //添加属性
    json.put("username", "张三");
    json.put("password", "123");
    //打印
    System.out.println(json);
    
    //增加属性
    json.element("sex", "男");
    json.put("age", 18);
    System.out.println(json);

根据key返回输出

System.out.println(json.get("sex"));

判断输出对象的类型

boolean isArray = json.isArray();
    boolean isEmpty = json.isEmpty();
    boolean isNullObject = json.isNullObject();
    System.out.println("是否数组："+isArray+", 是否空："+isEmpty+", 是否空为空对象："+isNullObject);

把JSONArray添加到JSONObject中

/把JSONArray添加到JSONObject中
    JSONArray jsonArray = new JSONArray();
    jsonArray.add(0, "张三");
    jsonArray.add(1, "123");
    //开始添加
    json.element("student", jsonArray);
    System.out.println(json);

全部代码：

import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    public class Json {
    	public static void main(String[] args) {
    		//创建JSONObject
    		JSONObject json = new JSONObject();
    		//添加属性
    		json.put("username", "张三");
    		json.put("password", "123");
    		//打印
    		System.out.println(json);
    		
    		//增加属性
    		json.element("sex", "男");
    		json.put("age", 18);
    		System.out.println(json);
    		
    		//根据key返回
    		System.out.println(json.get("sex"));
    		
    		//判断输出对象的类型
    		boolean isArray = json.isArray();
    		boolean isEmpty = json.isEmpty();
    		boolean isNullObject = json.isNullObject();
    		System.out.println("是否数组："+isArray+", 是否空："+isEmpty+", 是否空为空对象："+isNullObject);
    		
    		System.out.println("=====");
    		
    		//把JSONArray添加到JSONObject中
    		JSONArray jsonArray = new JSONArray();
    		jsonArray.add(0, "张三");
    		jsonArray.add(1, "123");
    		//开始添加
    		json.element("student", jsonArray);
    		System.out.println(json);
    	}
    }

运行结果：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70][]

# JSONArray #

创建JSONArray，添加属性值

//创建JSONArray
    JSONArray jsonArray = new JSONArray();
    //添加
    jsonArray.add(0, "张三");
    jsonArray.add(1, "123");
    jsonArray.element("男");
    System.

根据下标返回输出

System.out.println(jsonArray.get(0));

根据下标设置新值，修改

jsonArray.set(0, "李四");
    System.out.println(jsonArray);

把JSONObject放入到JSONArray中

//把JSONObject放入到JSONArray中
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("username", "张三");
    jsonObject.put("password", "123");
    jsonArray.add(jsonObject);
    System.

全部代码：

import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    public class Json {
    	public static void main(String[] args) {
    		//创建JSONArray
    		JSONArray jsonArray = new JSONArray();
    		//添加
    		jsonArray.add(0, "张三");
    		jsonArray.add(1, "123");
    		jsonArray.element("男");
    		System.out.println(jsonArray);
    		
    		//根据下标返回输出
    		System.out.println(jsonArray.get(0));
    		
    		//根据下标设置新值，修改
    		jsonArray.set(0, "李四");
    		System.out.println(jsonArray);
    		
    		//把JSONObject放入到JSONArray中
    		JSONObject jsonObject = new JSONObject();
    		jsonObject.put("username", "张三");
    		jsonObject.put("password", "123");
    		jsonArray.add(jsonObject);
    		System.out.println(jsonArray);
    		
    		//循环输出
    		for(int i = 0; i < jsonArray.size(); i++) {
    			System.out.println(jsonArray.get(i));
    		}
    	}
    }

运行结果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 1][]

# JavaBean与json字符串互转 #

student类：

public class Student {
    	private String username;
    	private String password;
    	public String getUsername() {
    		return username;
    	}
    	public void setUsername(String username) {
    		this.username = username;
    	}
    	public String getPassword() {
    		return password;
    	}
    	public void setPassword(String password) {
    		this.password = password;
    	}
    	public Student(String username, String password) {
    		super();
    		this.username = username;
    		this.password = password;
    	}
    	public Student() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	@Override
    	public String toString() {
    		return "Student [username=" + username + ", password=" + password + "]";
    	}
    }

定义对象，JavaBean对象转json字符串

//定义对象
    Student stu = new Student("张三", "123456");
    //JavaBean对象转json字符串
    JSONObject jsonObject = JSONObject.fromObject(stu);
    System.out.println(jsonObject);

json字符串转为javaBean

//json字符串转为javaBean
    //定义json字符串
    String jsondata = "{\"username\":\"李四\", \"password\":\"123\"}";
    //转为json对象
    JSONObject json = JSONObject.fromObject(jsondata);
    //转为JavaBean对象
    Student stu2 = (Student)JSONObject.toBean(json, Student.class);
    System.out.println(stu2.toString());

全部代码：

import net.sf.json.JSONObject;
    
    public class Json {
    	public static void main(String[] args) {
    		//定义对象
    		Student stu = new Student("张三", "123456");
    		//JavaBean对象转json字符串
    		JSONObject jsonObject = JSONObject.fromObject(stu);
    		System.out.println(jsonObject);
    		
    		//json字符串转为javaBean
    		//定义json字符串
    		String jsondata = "{\"username\":\"李四\", \"password\":\"123\"}";
    		//转为json对象
    		JSONObject json = JSONObject.fromObject(jsondata);
    		//转为JavaBean对象
    		Student stu2 = (Student)JSONObject.toBean(json, Student.class);
    		System.out.println(stu2.toString());
    	}
    }

输出结果：

![20191105200609673.png][]

# List与json字符串互转 #

先定义list集合，list转json字符串

//定义list集合
    List list = new ArrayList();
    list.add(new Student("张三", "123"));
    list.add(new Student("李四", "456"));
    //list转json字符串
    JSONArray jsonArray = JSONArray.fromObject(list);
    System.out.println(jsonArray);

json字符串转list

//json字符串转list
    List list2 = new ArrayList();
    String jsondata = "[{\"password\":\"123\",\"username\":\"张三\"},{\"password\":\"456\",\"username\":\"李四\"}]";
    JSONArray jsonArray1 = JSONArray.fromObject(jsondata);
    for(int i = 0; i < jsonArray1.size(); i++) {
    	JSONObject jsonObject2 = jsonArray1.getJSONObject(i);
    	Student stu2 = (Student)JSONObject.toBean(jsonObject2, Student.class);
    	list2.add(stu2);
    }
    System.out.println(list2);

全部代码

import java.util.ArrayList;
    import java.util.List;
    
    import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    public class Json {
    	public static void main(String[] args) {
    		//定义list集合
    		List list = new ArrayList();
    		list.add(new Student("张三", "123"));
    		list.add(new Student("李四", "456"));
    		//list转json字符串
    		JSONArray jsonArray = JSONArray.fromObject(list);
    		System.out.println(jsonArray);
    		
    		//json字符串转list
    		List list2 = new ArrayList();
    		String jsondata = "[{\"password\":\"123\",\"username\":\"张三\"},{\"password\":\"456\",\"username\":\"李四\"}]";
    		JSONArray jsonArray1 = JSONArray.fromObject(jsondata);
    		for(int i = 0; i < jsonArray1.size(); i++) {
    			JSONObject jsonObject2 = jsonArray1.getJSONObject(i);
    			Student stu2 = (Student)JSONObject.toBean(jsonObject2, Student.class);
    			list2.add(stu2);
    		}
    		System.out.println(list2);
    	}
    }

运行结果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 2][]

# Map与json字符串互转 #

定义map集合，Map转json字符串

//定义map集合
    Map map = new HashMap();
    map.put("1", new Student("张三", "123"));
    map.put("2", new Student("李四", "456"));
    //Map转json字符串
    JSONObject jsonMap = JSONObject.fromObject(map);
    System.out.println(jsonMap);

定义字符串map集合，map集合字符串转为map

//定义字符串map集合
    String jsondata = "{\"1\":{\"password\":\"123\",\"username\":\"张三\"},\"2\":{\"password\":\"456\",\"username\":\"李四\"}}";
    //map集合字符串转为map
    Map map2 = (Map)JSONObject.fromObject(jsondata);
    Set set = map2.keySet();
    //定义迭代器，迭代输出
    Iterator ite = set.iterator();
    while(ite.hasNext()) {
    	//取出一个字符串对象
    	String key = (String)ite.next();
    	//转为json格式
    	JSONObject jsonObject = JSONObject.fromObject(map2.get(key));
    	//转为对象
    	Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);
    	System.out.println(key+"   "+stu);
    }

全部代码

import java.util.HashMap;
    import java.util.Iterator;
    import java.util.Map;
    import java.util.Set;
    
    import net.sf.json.JSONObject;
    
    public class Json {
    	public static void main(String[] args) {
    		//定义map集合
    		Map map = new HashMap();
    		map.put("1", new Student("张三", "123"));
    		map.put("2", new Student("李四", "456"));
    		//Map转json字符串
    		JSONObject jsonMap = JSONObject.fromObject(map);
    		System.out.println(jsonMap);
    		
    		//定义字符串map集合
    		String jsondata = "{\"1\":{\"password\":\"123\",\"username\":\"张三\"},\"2\":{\"password\":\"456\",\"username\":\"李四\"}}";
    		//map集合字符串转为map
    		Map map2 = (Map)JSONObject.fromObject(jsondata);
    		Set set = map2.keySet();
    		//定义迭代器，迭代输出
    		Iterator ite = set.iterator();
    		while(ite.hasNext()) {
    			//取出一个字符串对象
    			String key = (String)ite.next();
    			//转为json格式
    			JSONObject jsonObject = JSONObject.fromObject(map2.get(key));
    			//转为对象
    			Student stu = (Student)JSONObject.toBean(jsonObject, Student.class);
    			System.out.println(key+"   "+stu);
    		}
    	}
    }

运行结果

![20191106071744350.png][]

# JSONArray与List互转 #

定义list集合，List转型JSONArray

//定义list集合
    List<Student> list = new ArrayList<Student>();
    list.add(new Student("张三", "123"));
    list.add(new Student("李四", "456"));
    //List转型JSONArray
    JSONArray jsonArray = JSONArray.fromObject(list);
    System.out.println(jsonArray.toString());

JSONArray转型List，JSONArray是用的上面的那个jsonArray变量

//JSONArray转型List
    List<Student> list2 = JSONArray.toList(jsonArray, new Student(), new JsonConfig());
    Iterator<Student> ite =  list2.iterator();
    while(ite.hasNext()) {
    	Student stu = ite.next();
    	System.out.println(stu);
    }

全部代码

import java.util.ArrayList;
    import java.util.Iterator;
    import java.util.List;
    
    import net.sf.json.JSONArray;
    import net.sf.json.JsonConfig;
    
    public class Json {
    	public static void main(String[] args) {
    		//定义list集合
    		List<Student> list = new ArrayList<Student>();
    		list.add(new Student("张三", "123"));
    		list.add(new Student("李四", "456"));
    		//List转型JSONArray
    		JSONArray jsonArray = JSONArray.fromObject(list);
    		System.out.println(jsonArray.toString());
    		
    		//JSONArray转型List
    		List<Student> list2 = JSONArray.toList(jsonArray, new Student(), new JsonConfig());
    		Iterator<Student> ite =  list2.iterator();
    		while(ite.hasNext()) {
    			Student stu = ite.next();
    			System.out.println(stu);
    		}
    	}
    }

运行结果

![20191106072615722.png][]

# JSONArray与数组互转 #

定义数组，数组转JSONArray

//定义数组
    boolean[] boolArray = {true, false, true};
    //java数组转JSONArray
    JSONArray jsonArray = JSONArray.fromObject(boolArray);
    System.out.println(jsonArray.toString());

JSONArray转java数组

//JSONArray转java数组
    Object obj[] = jsonArray.toArray();
    for(Object o : obj) {
    	System.out.print(o+"\t");
    }

全部代码

import net.sf.json.JSONArray;
    
    public class Json {
    	public static void main(String[] args) {
    		//定义数组
    		boolean[] boolArray = {true, false, true};
    		//java数组转JSONArray
    		JSONArray jsonArray = JSONArray.fromObject(boolArray);
    		System.out.println(jsonArray.toString());
    		
    		//JSONArray转java数组
    		Object obj[] = jsonArray.toArray();
    		for(Object o : obj) {
    			System.out.print(o+"\t");
    		}
    	}
    }

运行结果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 3][]

**推荐链接：[Alibaba Fastjson——超好用的JOSN解析库][Alibaba Fastjson_JOSN]**

[20191105182121613.png]: https://img-blog.csdnimg.cn/20191105182121613.png
[https_pan.baidu.com_s_1iZiXw55TPwIxYFQQCaR9Gw]: https://pan.baidu.com/s/1iZiXw55TPwIxYFQQCaR9Gw
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20191105191952360.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191105193820590.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2,size_16,color_FFFFFF,t_70
[20191105200609673.png]: https://img-blog.csdnimg.cn/20191105200609673.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20191105202442797.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2,size_16,color_FFFFFF,t_70
[20191106071744350.png]: https://img-blog.csdnimg.cn/20191106071744350.png
[20191106072615722.png]: https://img-blog.csdnimg.cn/20191106072615722.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20191106073408318.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwMjA1MTE2,size_16,color_FFFFFF,t_70
[Alibaba Fastjson_JOSN]: https://blog.csdn.net/qq_40205116/article/details/102865704