json-lib使用，JSONObject和JSONArray

朴灿烈づ我的快乐病毒、 2022-08-06 11:17 162阅读 0赞

1.**从Object到String**  
要先用Object对象构造一个JSONObject或者JSONArray对象，然后调用它的toString()方法即可

（1）示例一

1 Book book=new Book();
    2 book.setName("Java");
    3 book.setPrice(52.3f);
    4 JSONObject object=JSONObject.fromObject(book);
    5 System.out.println(object.toString());

（2）示例二

![复制代码][copycode.gif]

1         Book book=new Book();
     2         book.setName("Java");
     3         book.setPrice(52.3f);
     4         
     5         Book book2=new Book();
     6         book2.setName("C");
     7         book2.setPrice(42.3f);
     8         List list=new ArrayList();
     9         list.add(book);
    10         list.add(book2);
    11         JSONArray arry=JSONArray.fromObject(list);
    12         System.out.println(arry.toString());
    13 //结果如下： 14 [{"name":"Java","price":52.3},{"name":"C","price":42.3}]

![复制代码][copycode.gif]

2.从String到Object  
要先用String对象构造一个JSONObject或者JSONArray对象  
(1)示例一

1 String json="{name:'Java',price:52.3}";    
    2 JSONObject object=JSONObject.fromObject(json);
    3 System.out.println(object.get("name")+" "+object.get("price"));

(2)示例二

![复制代码][copycode.gif]

1 String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";
    2 JSONArray array=JSONArray.fromObject(json);
    3 for(int i=0;i<array.size();i++){
        
    4     Map o=(Map)array.get(i);
    5     System.out.println(o.get("name")+" "+o.get("price"));
    6 }

![复制代码][copycode.gif]

3.从String到Bean

(1)单个Bean对象

1  String json="{name:'Java',price:52.3}";
    2         JSONObject object=JSONObject.fromObject(json);
    3         Product product=(Product)JSONObject.toBean(object,Product.class);
    4         System.out.println(product.getName()+" "+product.getPrice());

(2).Bean的数组

![复制代码][copycode.gif]

1         String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";
    2         JSONArray array=JSONArray.fromObject(json);
    3         Product[] products=(Product[]) JSONArray.toArray(array,Product.class);
    4         for(Product p:products){
        
    5             System.out.println(p.getName()+" "+p.getPrice());
    6         }

![复制代码][copycode.gif]

自定义封装JSON操作的类

![复制代码][copycode.gif]

1 package com.util;
     2 
     3 import java.util.List;
     4 import java.util.Map;
     5 
     6 import net.sf.json.JSONArray;
     7 import net.sf.json.JSONObject;
     8 
     9 public class JsonHelper {
       
    10     //从普通的Bean转换为字符串 11     public static String getJson(Object o){
       
    12         JSONObject jo=JSONObject.fromObject(o);
    13         return jo.toString();
    14     }
    15     //从Java的列表转换为字符串 16     public static String getJson(List list){
       
    17         JSONArray ja=JSONArray.fromObject(list);
    18         return ja.toString();
    19     }
    20     //从Java对象数组转换为字符串 21     public static String getJson(Object[] arry){
       
    22         JSONArray ja=JSONArray.fromObject(arry);
    23         return ja.toString();
    24     }
    25     //从json格式的字符串转换为Map对象 26     public static Map getObject(String s){
       
    27         return     JSONObject.fromObject(s);
    28     }
    29     //从json格式的字符串转换为List数组 30     public static List getArray(String s){
       
    31         return JSONArray.fromObject(s);
    32     }
    33     //从json格式的字符串转换为某个Bean 34     public static Object getObject(String s,Class cls){
       
    35         JSONObject jo=JSONObject.fromObject(s);
    36         return JSONObject.toBean(jo, cls);
    37     }
    38     //从json格式的字符串转换为某类对象的数组 39     public static Object getArray(String s,Class cls){
       
    40         JSONArray ja=JSONArray.fromObject(s);
    41         return JSONArray.toArray(ja, cls);
    42     }
    43 }

[copycode.gif]: /images/20220806/8c134f817eda4145a3da5ecc7f976a74.png