json学习

川长思鸟来 2023-05-31 12:12 12阅读 0赞

### 一、json转对象 ###

import com.alibaba.fastjson.JSONArray;
    import com.alibaba.fastjson.JSONObject;
    
    public class JsonTest {
    	public static void main(String[] args) {
    		String json = "{\"id\":\"20\",\"name\":\"娃哈哈\",\"items\":[{\"itemId\":\"20\",\"itemName\":\"每天教育\"},{\"itemId\":\"21\",\"itemName\":\"你好课堂\"}]}";
    		JSONObject jsonObject = JSONObject.parseObject(json);
    		String id = jsonObject.getString("id");
    		String name = jsonObject.getString("name");
    		System.out.println(id+":" +name);
    		JSONArray jsonArray = jsonObject.getJSONArray("items");
    		for (int i = 0; i < jsonArray.size(); i++) {
    			JSONObject obj = jsonArray.getJSONObject(i);
    			String itemId = obj.getString("itemId");
    			String itemName = obj.getString("itemName");
    			System.out.println("itemId:"+itemId);
    			System.out.println("itemName:"+itemName);
    		}
    		User user = JSONObject.parseObject(json, User.class);
    		System.out.println(user);
    	}
    }

### 二、自定义json字符串对象 ###

import java.util.ArrayList;
    import java.util.List;
    
    import com.alibaba.fastjson.JSONObject;
    
    public class JsonTest2 {
    	public static void main(String[] args) {
    		/**
    		 * 自定义json
    		 */
    		JSONObject root = new JSONObject();
    		root.put("id", 1);
    		root.put("name", "sunla");
    		List<Item> item = new ArrayList<Item>();
    		Item i1 = new Item();
    		i1.setItemId("1");
    		i1.setItemName("hah");
    		Item i2 = new Item();
    		i2.setItemId("2");
    		i2.setItemName("www");
    		item.add(i1);
    		item.add(i2);
    		root.put("items", item);
    		System.out.println(root.toJSONString());
    		
    	}
    }

### 三、对象转成json字符串对象 ###

import java.util.ArrayList;
    import java.util.List;
    
    import com.alibaba.fastjson.JSONObject;
    
    public class JsonTest2 {
    	public static void main(String[] args) {
    		
    		/**
    		 * 对象转成json字符串对象
    		 */
    		User user = new User();
    		user.setId("1");
    		user.setName("banana");
    		List<Item> items = new ArrayList<Item>();
    		Item i3 = new Item();
    		i3.setItemId("11");
    		i3.setItemName("aaa");
    		Item i4 = new Item();
    		i4.setItemId("22");
    		i4.setItemName("bbb");
    		items.add(i3);
    		items.add(i4);
    		user.setItems(items);
    		System.out.println(new JSONObject().toJSONString(user));
    		
    	}
    }

用到的类

import java.util.List;
    
    public class User {
    	private String id;
    	private String name;
    	private List<Item> items;
    	public String getId() {
    		return id;
    	}
    	public void setId(String id) {
    		this.id = id;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public List<Item> getItems() {
    		return items;
    	}
    	public void setItems(List<Item> items) {
    		this.items = items;
    	}
    	@Override
    	public String toString() {
    		return "User [id=" + id + ", name=" + name + ", items=" + items + "]";
    	}
    }
    
    class Item{
    	private String itemId;
    	private String itemName;
    	public String getItemId() {
    		return itemId;
    	}
    	public void setItemId(String itemId) {
    		this.itemId = itemId;
    	}
    	public String getItemName() {
    		return itemName;
    	}
    	public void setItemName(String itemName) {
    		this.itemName = itemName;
    	}
    	@Override
    	public String toString() {
    		return "Item [itemId=" + itemId + ", itemName=" + itemName + "]";
    	}
    }