Json-lib使用——JSONObject與JSONArray

1.從Object到String
 要先用Object對象構造一個JSONObject或者JSONArray對象，而後調用它的toString()方法便可

（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

 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 //結果以下：
14 [{"name":"Java","price":52.3},{"name":"C","price":42.3}]

2.從String到Object
 要先用String對象構造一個JSONObject或者JSONArray對象
(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

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 }

3.從String到Bean

(1)單個Bean對象

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的數組

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         }

自定義封裝JSON操做的類

 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     //從普通的Bean轉換爲字符串
11     public static String getJson(Object o){
12         JSONObject jo=JSONObject.fromObject(o);
13         return jo.toString();
14     }
15     //從Java的列表轉換爲字符串
16     public static String getJson(List list){
17         JSONArray ja=JSONArray.fromObject(list);
18         return ja.toString();
19     }
20     //從Java對象數組轉換爲字符串
21     public static String getJson(Object[] arry){
22         JSONArray ja=JSONArray.fromObject(arry);
23         return ja.toString();
24     }
25     //從json格式的字符串轉換爲Map對象
26     public static Map getObject(String s){
27         return     JSONObject.fromObject(s);
28     }
29     //從json格式的字符串轉換爲List數組
30     public static List getArray(String s){
31         return JSONArray.fromObject(s);
32     }
33     //從json格式的字符串轉換爲某個Bean
34     public static Object getObject(String s,Class cls){
35         JSONObject jo=JSONObject.fromObject(s);
36         return JSONObject.toBean(jo, cls);
37     }
38     //從json格式的字符串轉換爲某類對象的數組
39     public static Object getArray(String s,Class cls){
40         JSONArray ja=JSONArray.fromObject(s);
41         return JSONArray.toArray(ja, cls);
42     }
43 }