JSONObject jo = JSONObject.fromObject(map);

//1. List集合转换成json代码 
List list = new ArrayList(); 
list.add( "first" ); 
list.add( "second" ); 
JSONArray jsonArray = JSONArray.fromObject( list ); 
//2. Map集合转换成json代码 
Map map = new HashMap(); 
map.put("name", "json"); 
map.put("bool", Boolean.TRUE); 
map.put("int", new Integer(1)); 
map.put("arr", new String[] { "a", "b" }); 
map.put("func", "function(i){ return this.arr[i]; }"); 
JSONObject json = JSONObject.fromObject(map); 
//3. Bean转换成json代码 
JSONObject jsonObject = JSONObject.fromObject(new JsonBean()); 
//4. 数组转换成json代码 
boolean[] boolArray = new boolean[] { true, false, true }; 
JSONArray jsonArray1 = JSONArray.fromObject(boolArray); 
//5. 一般数据转换成json代码 
JSONArray jsonArray3 = JSONArray.fromObject("['json','is','easy']" );