Spring Assert(来自Spring源码)

这个Spring的通用类在代码中使用起来非常简洁！

Spring的工具类，在平时项目中完全可以重新打包使用！

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public abstract class Assert {/** * Assert a boolean expression, throwing * <code>IllegalArgumentException</code> if the test result is * <code>false</code>. * <pre> * Assert.isTrue(i > 0, "The value must be greater than zero");</pre> * @param expression a boolean expression * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if expression is <code>false</code> */public static void isTrue(boolean expression, String message) {if (!expression) {throw new IllegalArgumentException(message);}}/** * Assert a boolean expression, throwing * <code>IllegalArgumentException</code> if the test result is * <code>false</code>. * <pre> * Assert.isTrue(i > 0);</pre> * @param expression a boolean expression * @throws IllegalArgumentException if expression is <code>false</code> */public static void isTrue(boolean expression) {isTrue(expression, "[Assertion failed] - this expression must be true");}/** * Assert that an object is not null. * <pre> * Assert.notNull(clazz, "The class must not be null");</pre> * @param object the object to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object is <code>null</code> */public static void notNull(Object object, String message) {if (object == null) {throw new IllegalArgumentException(message);}}/** * Assert that an object is not null. * <pre> * Assert.notNull(clazz);</pre> * @param object the object to check * @throws IllegalArgumentException if the object is <code>null</code> */public static void notNull(Object object) {notNull(object, "[Assertion failed] - this argument is required; it cannot be null");}/** * Assert that a string is not empty; that is, it must not be null and not empty. * <pre> * Assert.hasLength(name, "Name must not be empty");</pre> * @param text the string to check * @see StringUtils#hasLength */public static void hasLength(String text, String message) {if (!StringUtils.hasLength(text)) {throw new IllegalArgumentException(message);}}/** * Assert that a string is not empty; that is, it must not be null and not empty. * <pre> * Assert.hasLength(name);</pre> * @param text the string to check * @see StringUtils#hasLength */public static void hasLength(String text) {hasLength(text, "[Assertion failed] - this string argument must have length; it cannot be null or empty");}/** * Assert that a string has valid text content; that is, it must not be null * and must contain at least one non-whitespace character. * <pre> * Assert.hasText(name, "Name must not be empty");</pre> * @param text the string to check * @see StringUtils#hasText */public static void hasText(String text, String message) {if (!StringUtils.hasText(text)) {throw new IllegalArgumentException(message);}}/** * Assert that a string has valid text content; that is, it must not be null * and must contain at least one non-whitespace character. * <pre> * Assert.hasText(name, "Name must not be empty");</pre> * @param text the string to check * @see StringUtils#hasText */public static void hasText(String text) {hasText(text,"[Assertion failed] - this string argument must have text; it cannot be null, empty, or blank");}/** * Assert that an array has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre> * Assert.notEmpty(array, "The array must have elements");</pre> * @param array the array to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements */public static void notEmpty(Object[] array, String message) {if (array == null || array.length == 0) {throw new IllegalArgumentException(message);}}/** * Assert that an array has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre> * Assert.notEmpty(array);</pre> * @param array the array to check * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements */public static void notEmpty(Object[] array) {notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");}/** * Assert that a collection has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre> * Assert.notEmpty(collection, "Collection must have elements");</pre> * @param collection the collection to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements */public static void notEmpty(Collection<?> collection, String message) {if (collection == null || collection.isEmpty()) {throw new IllegalArgumentException(message);}}/** * Assert that a collection has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre> * Assert.notEmpty(collection, "Collection must have elements");</pre> * @param collection the collection to check * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements */public static void notEmpty(Collection<?> collection) {notEmpty(collection,"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");}/** * Assert that a Map has entries; that is, it must not be <code>null</code> * and must have at least one entry. * <pre> * Assert.notEmpty(map, "Map must have entries");</pre> * @param map the map to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the map is <code>null</code> or has no entries */public static void notEmpty(Map<?,?> map, String message) {if (map == null || map.isEmpty()) {throw new IllegalArgumentException(message);}}/** * Assert that a Map has entries; that is, it must not be <code>null</code> * and must have at least one entry. * <pre> * Assert.notEmpty(map);</pre> * @param map the map to check * @throws IllegalArgumentException if the map is <code>null</code> or has no entries */public static void notEmpty(Map<?,?> map) {notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");}/** * Assert that the provided object is an instance of the provided class. * <pre> * Assert.instanceOf(Foo.class, foo);</pre> * @param clazz the required class * @param obj the object to check * @throws IllegalArgumentException if the object is not an instance of clazz * @see Class#isInstance */public static void isInstanceOf(Class<?> clazz, Object obj) {isInstanceOf(clazz, obj, "");}/** * Assert that the provided object is an instance of the provided class. * <pre> * Assert.instanceOf(Foo.class, foo);</pre> * @param clazz the required class * @param obj the object to check * @param message a message which will be prepended to the message produced by * the function itself, and which may be used to provide context. It should * normally end in a ":" or ". " so that the function generate message looks * ok when prepended to it. * @throws IllegalArgumentException if the object is not an instance of clazz * @see Class#isInstance */public static void isInstanceOf(Class<?> clazz, Object obj, String message) {Assert.notNull(clazz, "The clazz to perform the instanceof assertion cannot be null");Assert.isTrue(clazz.isInstance(obj), message +"Object of class '" + (obj != null ? obj.getClass().getName() : "[null]") +"' must be an instance of '" + clazz.getName() + "'");}/** * Assert a boolean expression, throwing <code>IllegalStateException</code> * if the test result is <code>false</code>. Call isTrue if you wish to * throw IllegalArgumentException on an assertion failure. * <pre> * Assert.state(id == null, "The id property must not already be initialized");</pre> * @param expression a boolean expression * @param message the exception message to use if the assertion fails * @throws IllegalStateException if expression is <code>false</code> */public static void state(boolean expression, String message) {if (!expression) {throw new IllegalStateException(message);}}/** * Assert a boolean expression, throwing <code>IllegalStateException</code> * if the test result is <code>false</code>. Call isTrue if you wish to * throw IllegalArgumentException on an assertion failure. * <pre> * Assert.state(id == null);</pre> * @param expression a boolean expression * @throws IllegalStateException if expression is <code>false</code> */public static void state(boolean expression) {state(expression, "[Assertion failed] - this state invariant must be true");}}