如何獲取Java中某個類型的默認值？

Question

我正在寫一個調用方法的包裝器，如果引發異常，則記錄它並返回一個默認值。

InvocationHandler invocationHandler = new InvocationHandler() { 
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 
     try { 
      return invokeOn(wrapped, method, args); 
     } catch (InvocationTargetException e) { 
      Throwable targetException = e.getTargetException(); 
      if (targetException instanceof Exception) { 
       errorReporter.exception(wrapped, (Exception) targetException); 
       return defaultValueFor(method.getReturnType()); 
      } else { 
       throw targetException; 
      } 
     } 
    } 
}; 

我想找到實現defaultValueFor的一個很好的方式，使其返回每個可能的類型一個很好的默認值 - 的

@SuppressWarnings("unchecked") 
protected static <T> T defaultValueFor(Class<T> claz) { 
    if (claz == boolean.class) 
     return (T) Boolean.FALSE; 
    if (claz == short.class) 
     return (T) Short.valueOf((short) 0); 
    if (claz == int.class) 
     return (T) Integer.valueOf(0); 
    if (claz == long.class) 
     return (T) Long.valueOf(0); 
    ... 
    return null; 
} 

相當於這種代碼必須在JMock的但有沒有比這個可怕的鍋爐板更好的實施？

Answer 1

class DefaultValues { 
    static final Map<Class<?>,Object> defaultValues = new HashMap<Class<?>,Object>(); 

    // load 
    static { 
     defaultValues.put(boolean.class, Boolean.FALSE); 
     defaultValues.put(byte.class, new Byte((byte)0)); 
     defaultValues.put(short.class, new Short((short)0)); 
     defaultValues.put(int.class, new Integer(0)); 
     defaultValues.put(long.class, new Long(0L)); 
     defaultValues.put(char.class, new Character('\0')); 
     defaultValues.put(float.class, new Float(0.0F)); 
     defaultValues.put(double.class, new Double(0.0)); 
    } 

    public static final <T> T defaultValueFor(Class<T> clazz) { 
     return (T)defaultValues.get(clazz); 
    } 

}