讀取資源文件的工具類.

import java.util.ResourceBundle;

import org.springframework.util.NumberUtils;

/**讀取資源文件的工具類.
 */
public class ConfigUtil {

    /**讀取資源文件中的鍵值信息.
     * 例如有鍵值名爲a，其對應的值爲整數類型，那麼方法即爲:readConfigForObject("a",Integer.class).
    * @param keyName 鍵值名
    * @param requiredType 返回數據類型
    * @return 指定的數據類型返回值或異常時返回null
    * @version v1.0.0
     */
    @SuppressWarnings("unchecked")
    public static <T> T readConfigForObject(String keyName,Class<T> requiredType){
        try {
            ResourceBundle rb = ResourceBundle.getBundle("config");
            Object object = rb.getObject(keyName);
            return (T) convertValueToRequiredType(object,requiredType);
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return null;
    }

    /**把指定的參數值轉換成指定數據類型對應的值
    * @param value 待轉換的參數值
    * @param requiredType 數據類型
    * @return 指定數據類型對應的值
    * @version v1.0.0
     */
    @SuppressWarnings("unchecked")
    protected static Object convertValueToRequiredType(Object value, Class requiredType) {
        if (String.class.equals(requiredType)) {
            return value.toString();
        } else if (Number.class.isAssignableFrom(requiredType)) {
            if (value instanceof Number) {
                // Convert original Number to target Number class.
                return NumberUtils.convertNumberToTargetClass(((Number) value), requiredType);
            }
            else {
                // Convert stringified value to target Number class.
                return NumberUtils.parseNumber(value.toString(), requiredType);
            }
        } else if(Boolean.class.equals(requiredType)) {
            return Boolean.valueOf(value.toString());
        } else {
            throw new IllegalArgumentException(
                    "Value [" + value + "] is of type [" + value.getClass().getName() +
                    "] and cannot be converted to required type [" + requiredType.getName() + "]");
        }
    }
}