Json-lib使用——JSONObject与JSONArray

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Bean34     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 }