JAVA核心知识点--使用org.json.JSONObject处理Json数据

爱被打了一巴掌 2022-04-17 02:27 366阅读 0赞

**目录**

引入org.json依赖

构建JSONObject

直接构建

使用Map构建

使用JavaBean构建

解析JSONObject

--------------------

# 引入org.json依赖 #

在 maven 项目中使用 org.json ，需引入依赖：

<dependency>
    			<groupId>org.json</groupId>
    			<artifactId>json</artifactId>
    			<version>20160810</version>
    		</dependency>

# 构建JSONObject #

## 直接构建 ##

可以直接使用 new 关键字实例化一个JSONObject对象，然后调用它的 put() 方法对其字段值进行设置。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BlbmdqdW5sZWU_size_16_color_FFFFFF_t_70][]

范例：

JSONObject jsonObj = new JSONObject();
    		jsonObj.put("female", true);
    		jsonObj.put("hobbies", Arrays.asList(new String[] { "yoga", "swimming" }));
    		jsonObj.put("discount", 9.5);
    		jsonObj.put("age", "26");
    		jsonObj.put("features", new HashMap<String, Integer>() {
    			private static final long serialVersionUID = 1L;
    			{
    				put("height", 175);
    				put("weight", 70);
    			}
    		});
    		System.out.println(jsonObj);

结果：

{
    	"features": {
    		"weight": 70,
    		"height": 175
    	},
    	"hobbies": ["yoga", "swimming"],
    	"discount": 9.5,
    	"female": true,
    	"age": 26
    }

## 使用Map构建 ##

范例：

Map<String, Object> map = new HashMap<String, Object>();
    		map.put("female", true);
    		map.put("hobbies", Arrays.asList(new String[] { "yoga", "swimming" }));
    		map.put("discount", 9.5);
    		map.put("age", "26");
    		map.put("features", new HashMap<String, Integer>() {
    			private static final long serialVersionUID = 1L;
    			{
    				put("height", 175);
    				put("weight", 70);
    			}
    		});
    		JSONObject jsonObj = new JSONObject(map);
    		System.out.println(jsonObj);

程序执行结果与上例相同。

## 使用JavaBean构建 ##

范例：

import java.util.Map;
    
    public class UserInfo {
    
    	private Boolean female;
    	private String[] hobbies;
    	private Double discount;
    	private Integer age;
    	private Map<String, Integer> features;
    
    	public Boolean getFemale() {
    		return female;
    	}
    
    	public void setFemale(Boolean female) {
    		this.female = female;
    	}
    
    	public String[] getHobbies() {
    		return hobbies;
    	}
    
    	public void setHobbies(String[] hobbies) {
    		this.hobbies = hobbies;
    	}
    
    	public Double getDiscount() {
    		return discount;
    	}
    
    	public void setDiscount(Double discount) {
    		this.discount = discount;
    	}
    
    	public Integer getAge() {
    		return age;
    	}
    
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    
    	public Map<String, Integer> getFeatures() {
    		return features;
    	}
    
    	public void setFeatures(Map<String, Integer> features) {
    		this.features = features;
    	}
    
    }

UserInfo userInfo = new UserInfo();
    		userInfo.setFemale(true);
    		userInfo.setHobbies(new String[] { "yoga", "swimming" });
    		userInfo.setDiscount(9.5);
    		userInfo.setAge(26);
    		userInfo.setFeatures(new HashMap<String, Integer>() {
    			private static final long serialVersionUID = 1L;
    			{
    				put("height", 175);
    				put("weight", 70);
    			}
    		});
    		JSONObject jsonObj = new JSONObject(userInfo);
    		System.out.println(jsonObj);

程序执行结果与上例相同。

# 解析JSONObject #

JSONObject为每一种数据类型都提供了一个getXXX(key)方法，例如：获取字符串类型的字段值就使用getString()方法，获取数组类型的字段值就使用getJSONArray()方法。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BlbmdqdW5sZWU_size_16_color_FFFFFF_t_70 1][]

范例：

// 获取基本类型数据
    		System.out.println("Female: " + jsonObj.getBoolean("female"));
    		System.out.println("Discount: " + jsonObj.getDouble("discount"));
    		System.out.println("Age: " + jsonObj.getLong("age"));
    		
    		// 获取JSONObject类型数据
    		JSONObject features = jsonObj.getJSONObject("features");
    		String[] names = JSONObject.getNames(features);
    		System.out.println("Features: ");
    		for (int i = 0; i < names.length; i++) {
    			System.out.println("\t"+features.get(names[i]));
    		}
    
    		// 获取数组类型数据
    		JSONArray hobbies = jsonObj.getJSONArray("hobbies");
    		System.out.println("Hobbies: ");
    		for (int i = 0; i < hobbies.length(); i++) {
    			System.out.println("\t"+hobbies.get(i));
    		}

结果：

Female: true
    Discount: 9.5
    Age: 26
    Features: 
    	70
    	175
    Hobbies: 
    	yoga
    	swimming

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BlbmdqdW5sZWU_size_16_color_FFFFFF_t_70]: /images/20220417/757513f04720474ea04daa4d81e57769.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3BlbmdqdW5sZWU_size_16_color_FFFFFF_t_70 1]: /images/20220417/e5c98f3f30104aff9bac98dd84779ee5.png