net.sf.json 将Json数组直接转换成List对象

问题描述:将json数组不能直接转换成list这种形式,只能转换成list

@Retention(RetentionPolicy.RUNTIME)
    public @interface ItemType {
        /**
         * 子类型的类名
         * 
         * @return
         */
        Class<?> classType();
    }

然后再需要转换成List的地方标记,如下:

class School {
    //标记list容器里面的对象类型
     @ItemType(classType=Student.class)
     List<Student> studnets;
    }

    class Student {

    }

下面实现解析代码

/**
     * 将json对象转换成bean
     * 
     * @param jsonObject
     * @param beanClass
     * @return
     */
    public static <T> T toBean(JSONObject jsonObject, Class<T> cls) {
        T obj = null;
        try {
            if (jsonObject != null) {
                Field fields[] = cls.getDeclaredFields();
                obj = cls.newInstance();
                for (Field field : fields) {
                    field.setAccessible(true);
                    if (jsonObject.has(field.getName())) {
                        field.setAccessible(true);
                        if (field.getType() == String.class) {
                            field.set(obj,
                                    jsonObject.getString(field.getName()));
                        } else if (field.getType() == Boolean.class) {
                            field.set(obj,
                                    jsonObject.getBoolean(field.getName()));
                        } else if (field.getType() == int.class) {
                            field.set(obj, jsonObject.getInt(field.getName()));
                        } else if (field.getType() == Integer.class) {
                            field.set(obj, jsonObject.getInt(field.getName()));
                        } else if (field.getType() == Long.class) {
                            field.set(obj, jsonObject.getLong(field.getName()));
                        } else if (field.getType() == Double.class) {
                            field.set(obj,
                                    jsonObject.getDouble(field.getName()));
                        } else if (field.getType() == List.class) {
                            JSONArray jsonArray = jsonObject.optJSONArray(field
                                    .getName());
                            //关键点,获取到注解的信息,然后通过反射获取到类型
                            ItemType itemType = field
                                    .getAnnotation(ItemType.class);
                            if (itemType != null && jsonArray != null) {
                                Class<?> item = itemType.classType();
                                List itemlist = new ArrayList();
                                for (int i = 0; i < jsonArray.size(); i++) {
                                    JSONObject object_child = jsonArray
                                            .getJSONObject(i);
                                    itemlist.add(toBean(object_child, item));
                                }
                                field.set(obj, itemlist);

                            } else {
                                throw new Exception(field.getType().toString()
                                        + " mush be had itemType");
                            }

                        } else {
                            field.set(obj, jsonObject.get(field.getName()));
                        }

                    }
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return obj;
    }