Json-lib使用 转载

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

 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}]

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

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.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

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         }

自定义封装JSON操作的类

 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 }