基于json-lib.jar包Json实例程序
1.从头或者从零开始，创建一个JSONObject(Creating a JSONObject from scratch)
实例1：
   JSONObject jsonObject = new JSONObject();
   jsonObject.element("name", "周星星");
   jsonObject.element("sex", "male");
   jsonObject.element("age", 18);
   jsonObject.element("job", "student");

   System.out.println(jsonObject.get("name"));// 周星星
   System.out.println(jsonObject.get("job"));// student
   System.out.println(jsonObject.getString("sex"));// male
   System.out.println(jsonObject.getInt("age"));// 18
实例2：
   JSONObject jsonObject = new JSONObject().element("string", "JSON").element("integer", "1").element("double", "2.0").element("boolean", "true");
   assertEquals("JSON", jsonObject.getString("string"));
   assertEquals(1, jsonObject.getInt("integer"));
   assertEquals(2.0d, jsonObject.getDouble("double"), 0d);
   assertTrue(jsonObject.getBoolean("boolean"));
   注：这是对实例1的一个简化版
  
2.使用一个JSON格式化字符串来创建一个JSONObject(Creating a JSONObject from a JSON formatted string)  
实例1：
   String json = "{name:\"周星星\",sex:\"male\",age:18,job:\"student\"}";
   JSONObject jsonObject = JSONObject.fromObject(json);
   //或者使用 JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(json);
   System.out.println(jsonObject.get("name"));// 周星星
   System.out.println(jsonObject.get("job"));// student
   System.out.println(jsonObject.getString("sex"));// male
   System.out.println(jsonObject.getInt("age"));// 18
实例2：
   String str = "{'string':'JSON', 'integer': 1, 'double': 2.0, 'boolean': true}";
   JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(str);
   assertEquals("JSON", jsonObject.getString("string"));
   assertEquals(1, jsonObject.getInt("integer"));
   assertEquals(2.0d, jsonObject.getDouble("double"), 0d);
   assertTrue(jsonObject.getBoolean("boolean"));
  
3.使用一个Map来创建一个JSONObject(Creating a JSONObject from a Map)
实例1：
   Map map = new HashMap();  
   map.put( "string", "JSON" );  
   map.put( "integer", "1" );  
   map.put( "double", "2.0" );  
   map.put( "boolean", "true" );  
   JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON( map );  
   assertEquals( "JSON", jsonObject.getString("string") );        
   assertEquals( 1, jsonObject.getInt("integer") );        
   assertEquals( 2.0d, jsonObject.getDouble("double"), 0d );        
   assertTrue( jsonObject.getBoolean("boolean") );

4.使用一个JavaBean来创建一个JSONObject(Creating a JSONObject from a JavaBean)
实例1：
public class Mybean {
   private String string;
   private int integer;
   private double dooble;
   private boolean bool;

   // getters & setters
}

Mybean bean = new Mybean();
bean.setString("JSON");
bean.setInteger(1);
bean.setDooble(2.0d);
bean.setBool(true);
JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(bean);
assertEquals("JSON", jsonObject.getString("string"));
assertEquals(1, jsonObject.getInt("integer"));
assertEquals(2.0d, jsonObject.getDouble("dooble"), 0d);
assertTrue(jsonObject.getBoolean("bool"));


由此可见，无论要转换的源是哪种类型，都可以使用(JSONObject) JSONSerializer.toJSON()或JSONObject.fromObject()来转换;