objectutils.java

EasyDBO是一个超轻量级对象-关系映射（Object/Relation Mapping

	/**
	 * Return the same value as <code>{@link Double#hashCode()}</code>.
	 * @see Double#hashCode()
	 */
	public static int hashCode(double dbl) {
		long bits = Double.doubleToLongBits(dbl);
		return hashCode(bits);
	}

	/**
	 * Return the same value as <code>{@link Float#hashCode()}</code>.
	 * @see Float#hashCode()
	 */
	public static int hashCode(float flt) {
		return Float.floatToIntBits(flt);
	}

	/**
	 * Return the same value as <code>{@link Long#hashCode()}</code>.
	 * @see Long#hashCode()
	 */
	public static int hashCode(long lng) {
		return (int) (lng ^ (lng >>> 32));
	}


	//---------------------------------------------------------------------
	// Convenience methods for content-based toString output
	//---------------------------------------------------------------------

	/**
	 * Return a String representation of the specified Object.
	 * <p>Returns {@link #NULL_STRING the String 'null'} if <code>obj</code> is
	 * <code>null</code>.
	 * @param obj the object whose String representation to return
	 * @return a String representation of <code>obj</code>
	 */
	public static String nullSafeToString(Object obj) {
		if (obj == null) {
			return NULL_STRING;
		}
		if (obj instanceof String) {
			return (String) obj;
		}
		if (obj instanceof Object[]) {
			return nullSafeToString((Object[]) obj);
		}
		if (obj instanceof boolean[]) {
			return nullSafeToString((boolean[]) obj);
		}
		if (obj instanceof byte[]) {
			return nullSafeToString((byte[]) obj);
		}
		if (obj instanceof char[]) {
			return nullSafeToString((char[]) obj);
		}
		if (obj instanceof double[]) {
			return nullSafeToString((double[]) obj);
		}
		if (obj instanceof float[]) {
			return nullSafeToString((float[]) obj);
		}
		if (obj instanceof int[]) {
			return nullSafeToString((int[]) obj);
		}
		if (obj instanceof long[]) {
			return nullSafeToString((long[]) obj);
		}
		if (obj instanceof short[]) {
			return nullSafeToString((short[]) obj);
		}
		return obj.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(Object[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append(String.valueOf(array[i]));
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(boolean[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}

			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(byte[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(char[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append("'" + array[i] + "'");
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(double[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}

			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(float[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}

			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(int[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(long[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of the contents of the specified array. The
	 * String representation consists of a list of the array's elements, enclosed
	 * in curly braces (<code>"{}"</code>). Adjacent elements are separated by
	 * the characters <code>", "</code> (a comma followed by a space). Returns
	 * <code>"null"</code> if <code>array</code> is <code>null</code>.
	 * @param array the array whose String representation to return
	 * @return a String representation of <code>array</code>
	 */
	public static String nullSafeToString(short[] array) {
		if (array == null) {
			return NULL_STRING;
		}
		int length = array.length;
		if (length == 0) {
			return EMPTY_ARRAY;
		}
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			if (i == 0) {
				buffer.append(ARRAY_START);
			}
			else {
				buffer.append(ARRAY_ELEMENT_SEPARATOR);
			}
			buffer.append(array[i]);
		}
		buffer.append(ARRAY_END);
		return buffer.toString();
	}

	/**
	 * Return a String representation of an object's overall identity.
	 * @param obj the object (may be <code>null</code>)
	 * @return the object's identity as String representation,
	 * or <code>null</code> if the object was <code>null</code>
	 */
	public static String identityToString(Object obj) {
		if (obj == null) {
			return EMPTY_STRING;
		}
		return obj.getClass().getName() + "@" + getIdentityHexString(obj);
	}

	/**
	 * Return a hex String form of an object's identity hash code.
	 * @param obj the object
	 * @return the object's identity code in hex notation
	 */
	public static String getIdentityHexString(Object obj) {
		return Integer.toHexString(System.identityHashCode(obj));
	}

	/**
	 * Return a content-based String representation if <code>obj</code> is
	 * not <code>null</code>; otherwise returns an empty <code>String</code>.
	 * <p>Differs from <code>nullSafeToString</code> in that it returns an
	 * empty String rather than "null" for a <code>null</code> value.
	 * @see #nullSafeToString(Object)
	 */
	public static String getDisplayString(Object obj) {
		if (obj == null) {
			return EMPTY_STRING;
		}
		return nullSafeToString(obj);
	}

}