Spring util工具类Assert源码

package org.springframework.util;

import java.util.Collection;
import java.util.Map;

/**
*该工具类采用抽象类定义，抽象类内部全采用静态方法
*通常情况下定义工具类有如下方法：
*Method I:定义final类，私有化构造函数，类内部全采用静态方法
*Method II:定义abstract类，类内部全采用静态方法
*Method III:不建议采用接口+静态方法 或者 非私有化构造函数+静态方法
*/
public abstract class Assert {
    /**
    该类包括:
    判断boolean    (true or false)
    判断object     (is null or not)
    判断string    (has length,has text，contains)
    判断array    (is empty)
    判断collection    (is empty)
    判断map    (is empty)
    判断instanceof
    判断assign
    判断state
    除基本数据类型数组之外基本覆盖全部数据类型
    基本数据类型数组是object对象，但是只能判断is null or not
    */

    //断言expression必须为true
    public static void isTrue(boolean expression, String message) {
        if (!expression) {
            throw new IllegalArgumentException(message);
        }
    }

    
    //断言expression必须为true
    public static void isTrue(boolean expression) {
        isTrue(expression, "[Assertion failed] - this expression must be true");
    }

    //断言object对象为空
    public static void isNull(Object object, String message) {
        if (object != null) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言object对象为空
    public static void isNull(Object object) {
        isNull(object, "[Assertion failed] - the object argument must be null");
    }

    //断言object对象不为空
    public static void notNull(Object object, String message) {
        if (object == null) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言object对象不为空
    public static void notNull(Object object) {
        notNull(object, "[Assertion failed] - this argument is required; it must not be null");
    }

    //断言text具有长度，即text != null && text.length()>0
    public static void hasLength(String text, String message) {
        if (!StringUtils.hasLength(text)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言text具有长度，即text != null && text.length()>0
    public static void hasLength(String text) {
        hasLength(text,
                "[Assertion failed] - this String argument must have length; it must not be null or empty");
    }

    //断言text具有非空白字符
    public static void hasText(String text, String message) {
        if (!StringUtils.hasText(text)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言text具有非空白字符
    public static void hasText(String text) {
        hasText(text,
                "[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");
    }

    //断言textToSearch包含substring
    public static void doesNotContain(String textToSearch, String substring, String message) {
        if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&
                textToSearch.contains(substring)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言textToSearch不包含substring
    public static void doesNotContain(String textToSearch, String substring) {
        doesNotContain(textToSearch, substring,
                "[Assertion failed] - this String argument must not contain the substring [" + substring + "]");
    }


    //断言array数组不为空,即array != null && array.length>0
    public static void notEmpty(Object[] array, String message) {
        if (ObjectUtils.isEmpty(array)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言array数组不为空,即array != null && array.length>0
    public static void notEmpty(Object[] array) {
        notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");
    }

    //断言array数组不包含空元素
    public static void noNullElements(Object[] array, String message) {
        if (array != null) {
            for (Object element : array) {
                if (element == null) {
                    throw new IllegalArgumentException(message);
                }
            }
        }
    }

    //断言array数组不包含空元素
    public static void noNullElements(Object[] array) {
        noNullElements(array, "[Assertion failed] - this array must not contain any null elements");
    }

    //断言collection集合不为空,即collection != null && collection.size>0
    public static void notEmpty(Collection<?> collection, String message) {
        if (CollectionUtils.isEmpty(collection)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言collection集合不为空,即collection != null && collection.size>0
    public static void notEmpty(Collection<?> collection) {
        notEmpty(collection,
                "[Assertion failed] - this collection must not be empty: it must contain at least 1 element");
    }

    //断言map不为空，即map != null && !map.isEmpty()
    public static void notEmpty(Map<?, ?> map, String message) {
        if (CollectionUtils.isEmpty(map)) {
            throw new IllegalArgumentException(message);
        }
    }

    //断言map不为空，即map != null && !map.isEmpty()
    public static void notEmpty(Map<?, ?> map) {
        notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");
    }


    //断言obj是clazz的实例
    public static void isInstanceOf(Class<?> clazz, Object obj) {
        isInstanceOf(clazz, obj, "");
    }

    //断言obj是type的实例
    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(
                    (StringUtils.hasLength(message) ? message + " " : "") +
                    "Object of class [" + (obj != null ? obj.getClass().getName() : "null") +
                    "] must be an instance of " + type);
        }
    }

    //断言suoerType是subType的父类
    public static void isAssignable(Class<?> superType, Class<?> subType) {
        isAssignable(superType, subType, "");
    }

    //断言suoerType是subType的父类
    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);
        }
    }


    //断言expression是true,不过抛出IllegalStateException而不是illegalArgumentException
    public static void state(boolean expression, String message) {
        if (!expression) {
            throw new IllegalStateException(message);
        }
    }

    //断言expression是true,不过抛出IllegalStateException而不是illegalArgumentException
    public static void state(boolean expression) {
        state(expression, "[Assertion failed] - this state invariant must be true");
    }

}

同时该类引用到StringUtils,CollectionUtils和ObjectUtils。