com.gitee.l0km.common.spring.util.Assert Maven / Gradle / Ivy
/*
* Copyright 2002-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.gitee.l0km.common.spring.util;
import com.google.common.base.Supplier;
/**
* Assertion utility class that assists in validating arguments.
*
* Useful for identifying programmer errors early and clearly at runtime.
*
*
For example, if the contract of a public method states it does not
* allow {@code null} arguments, {@code Assert} can be used to validate that
* contract. Doing this clearly indicates a contract violation when it
* occurs and protects the class's invariants.
*
*
Typically used to validate method arguments rather than configuration
* properties, to check for cases that are usually programmer errors rather
* than configuration errors. In contrast to configuration initialization
* code, there is usually no point in falling back to defaults in such methods.
*
*
This class is similar to JUnit's assertion library. If an argument value is
* deemed invalid, an {@link IllegalArgumentException} is thrown (typically).
* For example:
*
*
* Assert.notNull(clazz, "The class must not be null");
* Assert.isTrue(i > 0, "The value must be greater than zero");
*
* Mainly for internal use within the framework; for a more comprehensive suite
* of assertion utilities consider {@code org.apache.commons.lang3.Validate} from
* Apache Commons Lang,
* Google Guava's
* Preconditions,
* or similar third-party libraries.
*
* @author Keith Donald
* @author Juergen Hoeller
* @author Sam Brannen
* @author Colin Sampaleanu
* @author Rob Harrop
*/
public abstract class Assert {
/**
* Assert a boolean expression, throwing an {@code IllegalArgumentException}
* if the expression evaluates to {@code false}.
*
Assert.isTrue(i > 0, "The value must be greater than zero");
* @param expression a boolean expression
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if {@code expression} is {@code false}
*/
public static void isTrue(boolean expression, String message) {
if (!expression) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert a boolean expression, throwing an {@code IllegalArgumentException}
* if the expression evaluates to {@code false}.
*
* Assert.isTrue(i > 0, () -> "The value '" + i + "' must be greater than zero");
*
* @param expression a boolean expression
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails
* @throws IllegalArgumentException if {@code expression} is {@code false}
*/
public static void isTrue(boolean expression, Supplier messageSupplier) {
if (!expression) {
throw new IllegalArgumentException(nullSafeGet(messageSupplier));
}
}
/**
* Assert that an object is {@code null}.
* Assert.isNull(value, "The value must be null");
* @param object the object to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the object is not {@code null}
*/
public static void isNull(Object object, String message) {
if (object != null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is {@code null}.
*
* Assert.isNull(value, () -> "The value '" + value + "' must be null");
*
* @param object the object to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails
* @throws IllegalArgumentException if the object is not {@code null}
*/
public static void isNull(Object object, Supplier messageSupplier) {
if (object != null) {
throw new IllegalArgumentException(nullSafeGet(messageSupplier));
}
}
/**
* Assert that an object is not {@code null}.
* Assert.notNull(clazz, "The class must not be null");
* @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}
*/
public static void notNull(Object object, String message) {
if (object == null) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that an object is not {@code null}.
*
* Assert.notNull(entity.getId(),
* () -> "ID for entity " + entity.getName() + " must not be null");
*
* @param object the object to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails
* @throws IllegalArgumentException if the object is {@code null}
*/
public static void notNull(Object object, Supplier messageSupplier) {
if (object == null) {
throw new IllegalArgumentException(nullSafeGet(messageSupplier));
}
}
/**
* Assert that the given String is not empty; that is,
* it must not be {@code null} and not the empty String.
* Assert.hasLength(name, "Name must not be empty");
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the text is empty
* @see StringUtils#hasLength
*/
public static void hasLength(String text, String message) {
if (!StringUtils.hasLength(text)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given String is not empty; that is,
* it must not be {@code null} and not the empty String.
*
* Assert.hasLength(account.getName(),
* () -> "Name for account '" + account.getId() + "' must not be empty");
*
* @param text the String to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails
* @throws IllegalArgumentException if the text is empty
* @see StringUtils#hasLength
*/
public static void hasLength(String text, Supplier messageSupplier) {
if (!StringUtils.hasLength(text)) {
throw new IllegalArgumentException(nullSafeGet(messageSupplier));
}
}
/**
* Assert that the given String contains valid text content; that is, it must not
* be {@code null} and must contain at least one non-whitespace character.
* Assert.hasText(name, "'name' must not be empty");
* @param text the String to check
* @param message the exception message to use if the assertion fails
* @throws IllegalArgumentException if the text does not contain valid text content
* @see StringUtils#hasText
*/
public static void hasText(String text, String message) {
if (!StringUtils.hasText(text)) {
throw new IllegalArgumentException(message);
}
}
/**
* Assert that the given String contains valid text content; that is, it must not
* be {@code null} and must contain at least one non-whitespace character.
*
* Assert.hasText(account.getName(),
* () -> "Name for account '" + account.getId() + "' must not be empty");
*
* @param text the String to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails
* @throws IllegalArgumentException if the text does not contain valid text content
* @see StringUtils#hasText
*/
public static void hasText(String text, Supplier messageSupplier) {
if (!StringUtils.hasText(text)) {
throw new IllegalArgumentException(nullSafeGet(messageSupplier));
}
}
/**
* Assert that the provided object is an instance of the provided class.
* Assert.instanceOf(Foo.class, foo, "Foo expected");
* @param type the type to check against
* @param obj the object to check
* @param message a message which will be prepended to provide further context.
* If it is empty or ends in ":" or ";" or "," or ".", a full exception message
* will be appended. If it ends in a space, the name of the offending object's
* type will be appended. In any other case, a ":" with a space and the name
* of the offending object's type will be appended.
* @throws IllegalArgumentException if the object is not an instance of type
*/
public static void isInstanceOf(Class type, Object obj, String message) {
notNull(type, "Type to check against must not be null");
if (!type.isInstance(obj)) {
instanceCheckFailed(type, obj, message);
}
}
/**
* Assert that the provided object is an instance of the provided class.
*
* Assert.instanceOf(Foo.class, foo, () -> "Processing " + Foo.class.getSimpleName() + ":");
*
* @param type the type to check against
* @param obj the object to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails. See {@link #isInstanceOf(Class, Object, String)} for details.
* @throws IllegalArgumentException if the object is not an instance of type
*/
public static void isInstanceOf(Class type, Object obj, Supplier messageSupplier) {
notNull(type, "Type to check against must not be null");
if (!type.isInstance(obj)) {
instanceCheckFailed(type, obj, nullSafeGet(messageSupplier));
}
}
/**
* Assert that the provided object is an instance of the provided class.
* Assert.instanceOf(Foo.class, foo);
* @param type the type to check against
* @param obj the object to check
* @throws IllegalArgumentException if the object is not an instance of type
*/
public static void isInstanceOf(Class type, Object obj) {
isInstanceOf(type, obj, "");
}
/**
* Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
* Assert.isAssignable(Number.class, myClass, "Number expected");
* @param superType the super type to check against
* @param subType the sub type to check
* @param message a message which will be prepended to provide further context.
* If it is empty or ends in ":" or ";" or "," or ".", a full exception message
* will be appended. If it ends in a space, the name of the offending sub type
* will be appended. In any other case, a ":" with a space and the name of the
* offending sub type will be appended.
* @throws IllegalArgumentException if the classes are not assignable
*/
public static void isAssignable(Class superType, Class subType, String message) {
notNull(superType, "Super type to check against must not be null");
if (subType == null || !superType.isAssignableFrom(subType)) {
assignableCheckFailed(superType, subType, message);
}
}
/**
* Assert that {@code superType.isAssignableFrom(subType)} is {@code true}.
*
* Assert.isAssignable(Number.class, myClass, () -> "Processing " + myAttributeName + ":");
*
* @param superType the super type to check against
* @param subType the sub type to check
* @param messageSupplier a supplier for the exception message to use if the
* assertion fails. See {@link #isAssignable(Class, Class, String)} for details.
* @throws IllegalArgumentException if the classes are not assignable
*/
public static void isAssignable(Class superType, Class subType, Supplier messageSupplier) {
notNull(superType, "Super type to check against must not be null");
if (subType == null || !superType.isAssignableFrom(subType)) {
assignableCheckFailed(superType, subType, nullSafeGet(messageSupplier));
}
}
private static void instanceCheckFailed(Class type, Object obj, String msg) {
String className = (obj != null ? obj.getClass().getName() : "null");
String result = "";
boolean defaultMessage = true;
if (StringUtils.hasLength(msg)) {
if (endsWithSeparator(msg)) {
result = msg + " ";
}
else {
result = messageWithTypeName(msg, className);
defaultMessage = false;
}
}
if (defaultMessage) {
result = result + ("Object of class [" + className + "] must be an instance of " + type);
}
throw new IllegalArgumentException(result);
}
private static void assignableCheckFailed(Class superType, Class subType, String msg) {
String result = "";
boolean defaultMessage = true;
if (StringUtils.hasLength(msg)) {
if (endsWithSeparator(msg)) {
result = msg + " ";
}
else {
result = messageWithTypeName(msg, subType);
defaultMessage = false;
}
}
if (defaultMessage) {
result = result + (subType + " is not assignable to " + superType);
}
throw new IllegalArgumentException(result);
}
private static boolean endsWithSeparator(String msg) {
return (msg.endsWith(":") || msg.endsWith(";") || msg.endsWith(",") || msg.endsWith("."));
}
private static String messageWithTypeName(String msg, Object typeName) {
return msg + (msg.endsWith(" ") ? "" : ": ") + typeName;
}
private static String nullSafeGet(Supplier messageSupplier) {
return (messageSupplier != null ? messageSupplier.get() : null);
}
}