序：

這些工具類不僅僅只侷限於spring框架的內部使用，完全可以作為獨立的工具類在我們編寫的專案中進行使用。好處便是程式碼質量提高，編寫效率加快。今天在閱讀

spring原始碼時，發現Assert類的使用，於是便參考網路資源，在這裡做一個記錄。

工具類：

斷言Assert類

包名-org.springframework.util

public abstract class Assert {
 	public static void isTrue(boolean expression, String message) {
 		if (!expression) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 1.根據某個表示式的boolean型別，進行斷言。
 	 */
 	public static void isTrue(boolean expression) {
 		isTrue(expression, "[Assertion failed] - this expression must be true");
 	}
 	public static void isNull(Object object, String message) {
 		if (object != null) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 2.根據物件是否為空進行斷言。不為空產生異常。
 	 * @param object
 	 */
 	public static void isNull(Object object) {
 		isNull(object, "[Assertion failed] - the object argument must be null");
 	}
 	public static void notNull(Object object, String message) {
 		if (object == null) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 3.根據物件是否為空進行斷言。為空產生異常。
 	 * @param object
 	 */
 	public static void notNull(Object object) {
 		notNull(object, "[Assertion failed] - this argument is required; it must not be null");
 	}
 	public static void hasLength(String text, String message) {
 		if (!StringUtils.hasLength(text)) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 4.根據字串內容是否為空/空值進行斷言，為空或空值則產生異常
 	 * @param text
 	 */
 	public static void hasLength(String text) {
 		hasLength(text,
 				"[Assertion failed] - this String argument must have length; it must not be null or empty");
 	}
 	public static void hasText(String text, String message) {
 		if (!StringUtils.hasText(text)) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 5.比4的斷言更嚴格，要求字串內容不能為空格字串所組成的。否則產生異常
 	 * @param text
 	 */
 	public static void hasText(String text) {
 		hasText(text,
 				"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
 	}
 	public static void doesNotContain(String textToSearch, String substring, String message) {
 		if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
 				textToSearch.indexOf(substring) != -1) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 6.根據字串是否包含子字串進行斷言，不包含則產生異常。
 	 * @param textToSearch
 	 * @param substring
 	 */
 	public static void doesNotContain(String textToSearch, String substring) {
 		doesNotContain(textToSearch, substring,
 				"[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
 	}
 	public static void notEmpty(Object[] array, String message) {
 		if (ObjectUtils.isEmpty(array)) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 
 	 * 
 	 * 7.根據陣列是否為空或者陣列長度為0進行斷言，滿足前者之一則發生異常。
 	 */
 	public static void notEmpty(Object[] array) {
 		notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
 	}
 	public static void noNullElements(Object[] array, String message) {
 		if (array != null) {
 			for (int i = 0; i < array.length; i++) {
 				if (array[i] == null) {
 					throw new IllegalArgumentException(message);
 				}
 			}
 		}
 	}
 	/**
 	 * 8.根據陣列是否包含null物件進行斷言，滿足則發生異常
 	 * @param array
 	 */
 	public static void noNullElements(Object[] array) {
 		noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
 	}
 	public static void notEmpty(Collection collection, String message) {
 		if (CollectionUtils.isEmpty(collection)) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 9.對集合型別是否為空或者元素為0進行斷言，滿足則發生異常
 	 * @param collection
 	 */
 	public static void notEmpty(Collection collection) {
 		notEmpty(collection,
 				"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
 	}
 	public static void notEmpty(Map map, String message) {
 		if (CollectionUtils.isEmpty(map)) {
 			throw new IllegalArgumentException(message);
 		}
 	}
 	/**
 	 * 10.對Map型別是否為空或者元素為0進行斷言，滿足則發生異常
 	 * @param map
 	 */
 	public static void notEmpty(Map map) {
 		notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
 	}
 	public static void isInstanceOf(Class clazz, Object obj) {
 		isInstanceOf(clazz, obj, "");
 	}
 	/**
 	 * 
 	 *11.根據型別是否所屬於指定型別進行斷言，不是則發生異常
 	 */
 	public static void isInstanceOf(Class type, Object obj, String message) {
 		notNull(type, "Type to check against must not be null");
 		if (!type.isInstance(obj)) {
 			throw new IllegalArgumentException(message +
 					"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
 					"] must be an instance of " + type);
 		}
 	}
 	/**
 	 * 12.subType必須可以按型別匹配於 superType，否則將丟擲異常；
 	 */
 	public static void isAssignable(Class superType, Class subType) {
 		isAssignable(superType, subType, "");
 	}
 	public static void isAssignable(Class superType, Class subType, String message) {
 		notNull(superType, "Type to check against must not be null");
 		if (subType == null || !superType.isAssignableFrom(subType)) {
 			throw new IllegalArgumentException(message + subType + " is not assignable to " + superType);
 		}
 	}
 	public static void state(boolean expression, String message) {
 		if (!expression) {
 			throw new IllegalStateException(message);
 		}
 	}
 	/**
 	 * 13.根據某個表示式的boolean型別，進行斷言。類似1
 	 * @param expression
 	 */
 	public static void state(boolean expression) {
 		state(expression, "[Assertion failed] - this state invariant must be true");
 	}
 
 }