Spring框架中ReflectionUtils类

这段代码是Spring框架中ReflectionUtils类的实现，主要用于简化Java反射操作，提供了一系列静态方法来处理反射相关的任务，如访问字段、方法、构造函数，以及调用方法等。它旨在提高代码的可读性和易用性，同时处理一些常见的反射相关的异常。

主要功能和目的

• 查找字段和方法：提供方法来查找类及其父类中的字段和方法，包括私有的和受保护的。
• 访问和修改字段值：允许获取和设置对象的字段值，即使字段是私有的。
• 调用方法：允许调用对象的方法，包括私有和受保护的方法。
• 处理反射异常：封装了对反射操作中可能抛出的异常的处理，简化了异常处理逻辑。
• 提高反射操作的可访问性：通过设置accessible标志，使得可以访问私有和受保护成员。

关键代码块或语句解释

1. 字段和方法过滤器：定义了MethodFilter和FieldFilter接口，允许用户根据自定义逻辑过滤方法和字段。

2. 查找字段：findField方法通过递归查找给定类及其父类中的字段，支持按名称和类型过滤。

3. 设置和获取字段值：setField和getField方法分别用于设置和获取字段的值，处理了访问权限和异常。

4. 查找方法：findMethod方法查找给定类及其父类中的方法，支持按名称和参数类型过滤。

5. 调用方法：invokeMethod方法用于调用目标对象的方法，处理了方法的访问权限和异常。

6. 异常处理：handleReflectionException和handleInvocationTargetException方法封装了对反射操作中可能抛出的异常的处理逻辑。

7. 提高可访问性：makeAccessible方法用于设置Field、Method或Constructor的accessible标志，以允许访问私有和受保护成员。

8. 缓存机制：使用ConcurrentReferenceHashMap缓存了类的字段和方法，以提高性能。

9. 与接口默认方法的交互：getDeclaredMethods方法中，对于接口，还会查找默认方法，这是Java 8引入的特性。

10. isPublicStaticFinal

• 功能：判断给定的字段是否为公共静态常量（public static final）。
• 实现：通过获取字段的修饰符（getModifiers），并检查是否同时具有public、static和final修饰符。

11. isEqualsMethod

• 功能：判断给定的方法是否为equals方法。
• 实现：首先检查方法名是否为equals，然后检查方法参数是否只有一个且类型为Object。

12. isHashCodeMethod

• 功能：判断给定的方法是否为hashCode方法。
• 实现：检查方法名是否为hashCode，并且方法没有参数。

13. isToStringMethod

• 功能：判断给定的方法是否为toString方法。
• 实现：检查方法名是否为toString，并且方法没有参数。

14. isObjectMethod

• 功能：判断给定的方法是否由java.lang.Object类声明。
• 实现：尝试在Object类中查找具有相同名称和参数类型的方法。如果找到，则返回true；如果抛出异常，则表示方法不是由Object类声明的。

15. isCglibRenamedMethod

• 功能：判断给定的方法是否为CGLIB库重命名的方法。
• 实现：检查方法名是否以特定的前缀（CGLIB$）开始，然后检查方法名的结尾是否符合CGLIB重命名的模式（即CGLIB$methodName$0）。

16. doWithLocalMethods 方法

• 作用: 对给定类中声明的所有方法执行指定的回调操作。
• 参数:
  • clazz: 要检查的类。
  • mc: 对每个方法执行的回调操作。
• 执行流程:
  • 首先，通过 getDeclaredMethods(clazz) 获取类中声明的所有方法。
  • 然后，遍历这些方法，对每个方法执行 mc.doWith(method)，即调用回调操作。
  • 如果访问方法时抛出 IllegalAccessException 异常，则抛出 IllegalStateException 异常，指示不允许访问该方法。

17. doWithMethods 方法（重载版本1）

• 作用: 对给定类及其超类中的所有匹配方法执行指定的回调操作。
• 参数:
  • clazz: 要检查的类。
  • mc: 对每个方法执行的回调操作。
• 执行流程:
  • 直接调用 doWithMethods(clazz, mc, null)，即使用 null 作为方法过滤器，表示不过滤任何方法。

18. doWithMethods 方法（重载版本2）

• 作用: 对给定类及其超类（或实现的接口）中的所有匹配方法执行指定的回调操作，允许通过过滤器指定哪些方法应该被处理。
• 参数:
  • clazz: 要检查的类。
  • mc: 对每个方法执行的回调操作。
  • mf: 决定哪些方法应该应用回调的过滤器。
• 执行流程:
  • 首先，通过 getDeclaredMethods(clazz) 获取类中声明的所有方法。
  • 遍历这些方法，如果设置了过滤器 mf 并且方法不匹配过滤器，则跳过该方法。
  • 对匹配的方法执行 mc.doWith(method)，即调用回调操作。
  • 如果访问方法时抛出 IllegalAccessException 异常，则抛出 IllegalStateException 异常。
  • 如果类有超类，则递归调用 doWithMethods 处理超类的方法。
  • 如果类是接口，并且没有超类，则遍历其所有接口，并对每个接口递归调用 doWithMethods。

19. getAllDeclaredMethods 方法

此方法的目的是获取指定类（leafClass）及其所有父类的所有声明方法。方法首先创建一个 ArrayList 来存储方法，然后使用 doWithMethods 方法遍历类和其父类的所有方法，并将它们添加到列表中。最后，将列表转换为数组并返回。

20. getUniqueDeclaredMethods 方法

此方法与 getAllDeclaredMethods 类似，但它只包括唯一的声明方法。这意味着，如果在子类中找到与父类相同签名的方法，则只包括子类中的方法。此外，如果存在协变返回类型（即子类方法覆盖父类方法，但返回类型是父类返回类型的子类型），则只包括具有最具体返回类型的方法。此方法还排除了CGLIB重命名的方法，这些方法不被视为用户定义的业务逻辑方法。

21. getDeclaredMethods 方法

这是一个私有方法，用于获取类的所有声明方法，包括从接口继承的默认方法。此方法首先尝试从缓存中获取方法数组，如果缓存中没有，则使用 Class.getDeclaredMethods 方法获取类的声明方法，并通过 findConcreteMethodsOnInterfaces 方法获取实现的接口中的默认方法。然后，这些方法被组合成一个数组，存储在缓存中以供将来使用。

这三个方法的区别

• getAllDeclaredMethods 方法
• getUniqueDeclaredMethods 方法
• getDeclaredMethods 方法

关键点解释
- 反射和声明方法：Java反射机制允许程序在运行时访问和操作类的成员（如字段和方法）。声明方法是指在类中明确定义的方法，不包括继承的方法。
- 协变返回类型：允许子类方法覆盖父类方法时返回父类返回类型的子类型。
- CGLIB重命名方法：CGLIB是一个第三方库，用于在运行时动态生成类和对象。它有时会创建带有特殊前缀的方法，这些方法不应被视为类的正常业务逻辑方法。
- 缓存：为了提高性能，方法数组被缓存起来，避免了重复的反射操作。

总结来说，getAllDeclaredMethods 和 getUniqueDeclaredMethods 方法都是用于获取类及其父类的所有声明方法，但后者会排除重复和特定情况下的方法。而 getDeclaredMethods 方法则更多用于内部处理，它包括了类声明的方法和接口默认方法，且使用了缓存机制以提高性能。

22. doWithLocalFields 方法

• 作用: 对给定类中本地声明的所有字段执行给定的回调操作。
• 参数:
  • clazz: 要分析的目标类。
  • fc: 对每个字段执行的回调。
• 执行流程:
  • 通过 getDeclaredFields(clazz) 获取类中声明的所有字段。
  • 遍历这些字段，对每个字段执行 fc.doWith(field) 回调操作。
  • 如果访问字段时抛出 IllegalAccessException 异常，则抛出 IllegalStateException。

23. doWithFields 方法 (重载1)

• 作用: 对目标类及其所有父类中声明的字段执行给定的回调操作。
• 参数:
  • clazz: 要分析的目标类。
  • fc: 对每个字段执行的回调。
• 执行流程:
  • 直接调用 doWithFields(clazz, fc, null)，不使用字段过滤器。

24. doWithFields 方法 (重载2)

• 作用: 对目标类及其所有父类中声明的字段执行给定的回调操作，可以通过字段过滤器控制哪些字段被处理。
• 参数:
  • clazz: 要分析的目标类。
  • fc: 对每个字段执行的回调。
  • ff: 决定哪些字段应用回调的字段过滤器。
• 执行流程:
  • 从目标类开始，沿着继承层次向上遍历每个类。
  • 对每个类，获取其声明的字段，并根据过滤器 ff 决定是否对字段执行回调 fc.doWith(field)。
  • 如果访问字段时抛出 IllegalAccessException 异常，则抛出 IllegalStateException。
  • 继续向上遍历直到 Object 类，Object 类没有父类，因此遍历在此结束。

25. getDeclaredFields 方法

• 作用: 从本地缓存中检索类声明的字段，以避免JVM的安全管理器检查和防御性数组复制。
• 参数:
  • clazz: 要内省的类。
• 执行流程:
  • 检查缓存中是否已有该类的字段信息，如果有，则直接返回。
  • 如果缓存中没有，使用 clazz.getDeclaredFields() 获取类声明的所有字段，并将结果存入缓存。
  • 如果在获取字段过程中出现异常，则抛出 IllegalStateException。

26. 清除缓存 (clearCache 方法)

这个方法用于清除内部的方法和字段缓存。这是为了确保在某些情况下，如动态修改了类的结构后，能够重新加载类的方法和字段信息，保证获取到的信息是最新的。

public static void clearCache() {declaredMethodsCache.clear();declaredFieldsCache.clear();
}

27. 方法回调接口 (MethodCallback)

这是一个函数式接口，定义了一个 doWith 方法，该方法接受一个 Method 对象作为参数。这个接口的目的是允许用户定义如何处理某个特定的方法。通过这种方式，用户可以自定义对类中每个方法的操作，例如访问、修改或者调用等。

@FunctionalInterface
public interface MethodCallback {void doWith(Method method) throws IllegalArgumentException, IllegalAccessException;
}

28. 方法过滤器接口 (MethodFilter)

这也是一个函数式接口，定义了一个 matches 方法，该方法接受一个 Method 对象作为参数，并返回一个布尔值。这个接口的目的是允许用户定义一个过滤条件，用于决定是否对某个方法执行操作。这样可以在执行方法回调之前，过滤掉不需要处理的方法。

@FunctionalInterface
public interface MethodFilter {boolean matches(Method method);
}

4. 字段回调接口 (FieldCallback)

   类似于 MethodCallback，这是一个函数式接口，定义了一个 doWith 方法，该方法接受一个 Field 对象作为参数。这个接口的目的是允许用户定义如何处理某个特定的字段。用户可以通过实现这个接口，自定义对类中每个字段的操作，例如访问、修改字段值等。

   @FunctionalInterface
   public interface FieldCallback {void doWith(Field field) throws IllegalArgumentException, IllegalAccessException;
   }
   

5. 字段过滤器接口 (FieldFilter)

   类似于 MethodFilter，这也是一个函数式接口，定义了一个 matches 方法，该方法接受一个 Field 对象作为参数，并返回一个布尔值。这个接口的目的是允许用户定义一个过滤条件，用于决定是否对某个字段执行操作。这样可以在执行字段回调之前，过滤掉不需要处理的字段。

   @FunctionalInterface
   public interface FieldFilter {boolean matches(Field field);
   }
   

总结

ReflectionUtils类是Spring框架提供的一个工具类，旨在简化Java反射的使用，使得开发者可以更方便地进行反射操作，同时减少了代码的冗余和复杂性。通过提供一系列静态方法，它帮助开发者在运行时查询和操作对象的状态，而无需直接处理底层的反射API和相关的异常处理。

源代码如下

/** Copyright 2002-2018 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**      http://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 org.springframework.util;import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.UndeclaredThrowableException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;import org.springframework.lang.Nullable;/*** Simple utility class for working with the reflection API and handling* reflection exceptions.** <p>Only intended for internal use.** @author Juergen Hoeller* @author Rob Harrop* @author Rod Johnson* @author Costin Leau* @author Sam Brannen* @author Chris Beams* @since 1.2.2*/
public abstract class ReflectionUtils {/*** Pre-built MethodFilter that matches all non-bridge methods.* @since 3.0* @deprecated as of 5.0.11, in favor of a custom {@link MethodFilter}*/@Deprecatedpublic static final MethodFilter NON_BRIDGED_METHODS =(method -> !method.isBridge());/*** Pre-built MethodFilter that matches all non-bridge non-synthetic methods* which are not declared on {@code java.lang.Object}.* @since 3.0.5*/public static final MethodFilter USER_DECLARED_METHODS =(method -> (!method.isBridge() && !method.isSynthetic() && method.getDeclaringClass() != Object.class));/*** Pre-built FieldFilter that matches all non-static, non-final fields.*/public static final FieldFilter COPYABLE_FIELDS =field -> !(Modifier.isStatic(field.getModifiers()) || Modifier.isFinal(field.getModifiers()));/*** Naming prefix for CGLIB-renamed methods.* @see #isCglibRenamedMethod*/private static final String CGLIB_RENAMED_METHOD_PREFIX = "CGLIB$";private static final Method[] NO_METHODS = {};private static final Field[] NO_FIELDS = {};/*** Cache for {@link Class#getDeclaredMethods()} plus equivalent default methods* from Java 8 based interfaces, allowing for fast iteration.*/private static final Map<Class<?>, Method[]> declaredMethodsCache = new ConcurrentReferenceHashMap<>(256);/*** Cache for {@link Class#getDeclaredFields()}, allowing for fast iteration.*/private static final Map<Class<?>, Field[]> declaredFieldsCache = new ConcurrentReferenceHashMap<>(256);/*** Attempt to find a {@link Field field} on the supplied {@link Class} with the* supplied {@code name}. Searches all superclasses up to {@link Object}.* @param clazz the class to introspect* @param name the name of the field* @return the corresponding Field object, or {@code null} if not found*/@Nullablepublic static Field findField(Class<?> clazz, String name) {return findField(clazz, name, null);}/*** Attempt to find a {@link Field field} on the supplied {@link Class} with the* supplied {@code name} and/or {@link Class type}. Searches all superclasses* up to {@link Object}.* @param clazz the class to introspect* @param name the name of the field (may be {@code null} if type is specified)* @param type the type of the field (may be {@code null} if name is specified)* @return the corresponding Field object, or {@code null} if not found*/@Nullablepublic static Field findField(Class<?> clazz, @Nullable String name, @Nullable Class<?> type) {Assert.notNull(clazz, "Class must not be null");Assert.isTrue(name != null || type != null, "Either name or type of the field must be specified");Class<?> searchType = clazz;while (Object.class != searchType && searchType != null) {Field[] fields = getDeclaredFields(searchType);for (Field field : fields) {if ((name == null || name.equals(field.getName())) &&(type == null || type.equals(field.getType()))) {return field;}}searchType = searchType.getSuperclass();}return null;}/*** Set the field represented by the supplied {@link Field field object} on the* specified {@link Object target object} to the specified {@code value}.* In accordance with {@link Field#set(Object, Object)} semantics, the new value* is automatically unwrapped if the underlying field has a primitive type.* <p>Thrown exceptions are handled via a call to {@link #handleReflectionException(Exception)}.* @param field the field to set* @param target the target object on which to set the field* @param value the value to set (may be {@code null})*/public static void setField(Field field, @Nullable Object target, @Nullable Object value) {try {field.set(target, value);}catch (IllegalAccessException ex) {handleReflectionException(ex);throw new IllegalStateException("Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());}}/*** Get the field represented by the supplied {@link Field field object} on the* specified {@link Object target object}. In accordance with {@link Field#get(Object)}* semantics, the returned value is automatically wrapped if the underlying field* has a primitive type.* <p>Thrown exceptions are handled via a call to {@link #handleReflectionException(Exception)}.* @param field the field to get* @param target the target object from which to get the field* @return the field's current value*/@Nullablepublic static Object getField(Field field, @Nullable Object target) {try {return field.get(target);}catch (IllegalAccessException ex) {handleReflectionException(ex);throw new IllegalStateException("Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());}}/*** Attempt to find a {@link Method} on the supplied class with the supplied name* and no parameters. Searches all superclasses up to {@code Object}.* <p>Returns {@code null} if no {@link Method} can be found.* @param clazz the class to introspect* @param name the name of the method* @return the Method object, or {@code null} if none found*/@Nullablepublic static Method findMethod(Class<?> clazz, String name) {return findMethod(clazz, name, new Class<?>[0]);}/*** Attempt to find a {@link Method} on the supplied class with the supplied name* and parameter types. Searches all superclasses up to {@code Object}.* <p>Returns {@code null} if no {@link Method} can be found.* @param clazz the class to introspect* @param name the name of the method* @param paramTypes the parameter types of the method* (may be {@code null} to indicate any signature)* @return the Method object, or {@code null} if none found*/@Nullablepublic static Method findMethod(Class<?> clazz, String name, @Nullable Class<?>... paramTypes) {Assert.notNull(clazz, "Class must not be null");Assert.notNull(name, "Method name must not be null");Class<?> searchType = clazz;while (searchType != null) {Method[] methods = (searchType.isInterface() ? searchType.getMethods() : getDeclaredMethods(searchType));for (Method method : methods) {if (name.equals(method.getName()) &&(paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {return method;}}searchType = searchType.getSuperclass();}return null;}/*** Invoke the specified {@link Method} against the supplied target object with no arguments.* The target object can be {@code null} when invoking a static {@link Method}.* <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.* @param method the method to invoke* @param target the target object to invoke the method on* @return the invocation result, if any* @see #invokeMethod(java.lang.reflect.Method, Object, Object[])*/@Nullablepublic static Object invokeMethod(Method method, @Nullable Object target) {return invokeMethod(method, target, new Object[0]);}/*** Invoke the specified {@link Method} against the supplied target object with the* supplied arguments. The target object can be {@code null} when invoking a* static {@link Method}.* <p>Thrown exceptions are handled via a call to {@link #handleReflectionException}.* @param method the method to invoke* @param target the target object to invoke the method on* @param args the invocation arguments (may be {@code null})* @return the invocation result, if any*/@Nullablepublic static Object invokeMethod(Method method, @Nullable Object target, @Nullable Object... args) {try {return method.invoke(target, args);}catch (Exception ex) {handleReflectionException(ex);}throw new IllegalStateException("Should never get here");}/*** Invoke the specified JDBC API {@link Method} against the supplied target* object with no arguments.* @param method the method to invoke* @param target the target object to invoke the method on* @return the invocation result, if any* @throws SQLException the JDBC API SQLException to rethrow (if any)* @see #invokeJdbcMethod(java.lang.reflect.Method, Object, Object[])* @deprecated as of 5.0.11, in favor of custom SQLException handling*/@Deprecated@Nullablepublic static Object invokeJdbcMethod(Method method, @Nullable Object target) throws SQLException {return invokeJdbcMethod(method, target, new Object[0]);}/*** Invoke the specified JDBC API {@link Method} against the supplied target* object with the supplied arguments.* @param method the method to invoke* @param target the target object to invoke the method on* @param args the invocation arguments (may be {@code null})* @return the invocation result, if any* @throws SQLException the JDBC API SQLException to rethrow (if any)* @see #invokeMethod(java.lang.reflect.Method, Object, Object[])* @deprecated as of 5.0.11, in favor of custom SQLException handling*/@Deprecated@Nullablepublic static Object invokeJdbcMethod(Method method, @Nullable Object target, @Nullable Object... args)throws SQLException {try {return method.invoke(target, args);}catch (IllegalAccessException ex) {handleReflectionException(ex);}catch (InvocationTargetException ex) {if (ex.getTargetException() instanceof SQLException) {throw (SQLException) ex.getTargetException();}handleInvocationTargetException(ex);}throw new IllegalStateException("Should never get here");}/*** Handle the given reflection exception. Should only be called if no* checked exception is expected to be thrown by the target method.* <p>Throws the underlying RuntimeException or Error in case of an* InvocationTargetException with such a root cause. Throws an* IllegalStateException with an appropriate message or* UndeclaredThrowableException otherwise.* @param ex the reflection exception to handle*/public static void handleReflectionException(Exception ex) {if (ex instanceof NoSuchMethodException) {throw new IllegalStateException("Method not found: " + ex.getMessage());}if (ex instanceof IllegalAccessException) {throw new IllegalStateException("Could not access method: " + ex.getMessage());}if (ex instanceof InvocationTargetException) {handleInvocationTargetException((InvocationTargetException) ex);}if (ex instanceof RuntimeException) {throw (RuntimeException) ex;}throw new UndeclaredThrowableException(ex);}/*** Handle the given invocation target exception. Should only be called if no* checked exception is expected to be thrown by the target method.* <p>Throws the underlying RuntimeException or Error in case of such a root* cause. Throws an UndeclaredThrowableException otherwise.* @param ex the invocation target exception to handle*/public static void handleInvocationTargetException(InvocationTargetException ex) {rethrowRuntimeException(ex.getTargetException());}/*** Rethrow the given {@link Throwable exception}, which is presumably the* <em>target exception</em> of an {@link InvocationTargetException}.* Should only be called if no checked exception is expected to be thrown* by the target method.* <p>Rethrows the underlying exception cast to a {@link RuntimeException} or* {@link Error} if appropriate; otherwise, throws an* {@link UndeclaredThrowableException}.* @param ex the exception to rethrow* @throws RuntimeException the rethrown exception*/public static void rethrowRuntimeException(Throwable ex) {if (ex instanceof RuntimeException) {throw (RuntimeException) ex;}if (ex instanceof Error) {throw (Error) ex;}throw new UndeclaredThrowableException(ex);}/*** Rethrow the given {@link Throwable exception}, which is presumably the* <em>target exception</em> of an {@link InvocationTargetException}.* Should only be called if no checked exception is expected to be thrown* by the target method.* <p>Rethrows the underlying exception cast to an {@link Exception} or* {@link Error} if appropriate; otherwise, throws an* {@link UndeclaredThrowableException}.* @param ex the exception to rethrow* @throws Exception the rethrown exception (in case of a checked exception)*/public static void rethrowException(Throwable ex) throws Exception {if (ex instanceof Exception) {throw (Exception) ex;}if (ex instanceof Error) {throw (Error) ex;}throw new UndeclaredThrowableException(ex);}/*** Determine whether the given method explicitly declares the given* exception or one of its superclasses, which means that an exception* of that type can be propagated as-is within a reflective invocation.* @param method the declaring method* @param exceptionType the exception to throw* @return {@code true} if the exception can be thrown as-is;* {@code false} if it needs to be wrapped*/public static boolean declaresException(Method method, Class<?> exceptionType) {Assert.notNull(method, "Method must not be null");Class<?>[] declaredExceptions = method.getExceptionTypes();for (Class<?> declaredException : declaredExceptions) {if (declaredException.isAssignableFrom(exceptionType)) {return true;}}return false;}/*** Determine whether the given field is a "public static final" constant.* @param field the field to check*/public static boolean isPublicStaticFinal(Field field) {int modifiers = field.getModifiers();return (Modifier.isPublic(modifiers) && Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers));}/*** Determine whether the given method is an "equals" method.* @see java.lang.Object#equals(Object)*/public static boolean isEqualsMethod(@Nullable Method method) {if (method == null || !method.getName().equals("equals")) {return false;}Class<?>[] paramTypes = method.getParameterTypes();return (paramTypes.length == 1 && paramTypes[0] == Object.class);}/*** Determine whether the given method is a "hashCode" method.* @see java.lang.Object#hashCode()*/public static boolean isHashCodeMethod(@Nullable Method method) {return (method != null && method.getName().equals("hashCode") && method.getParameterCount() == 0);}/*** Determine whether the given method is a "toString" method.* @see java.lang.Object#toString()*/public static boolean isToStringMethod(@Nullable Method method) {return (method != null && method.getName().equals("toString") && method.getParameterCount() == 0);}/*** Determine whether the given method is originally declared by {@link java.lang.Object}.*/public static boolean isObjectMethod(@Nullable Method method) {if (method == null) {return false;}try {Object.class.getDeclaredMethod(method.getName(), method.getParameterTypes());return true;}catch (Exception ex) {return false;}}/*** Determine whether the given method is a CGLIB 'renamed' method,* following the pattern "CGLIB$methodName$0".* @param renamedMethod the method to check* @see org.springframework.cglib.proxy.Enhancer#rename*/public static boolean isCglibRenamedMethod(Method renamedMethod) {String name = renamedMethod.getName();if (name.startsWith(CGLIB_RENAMED_METHOD_PREFIX)) {int i = name.length() - 1;while (i >= 0 && Character.isDigit(name.charAt(i))) {i--;}return ((i > CGLIB_RENAMED_METHOD_PREFIX.length()) &&(i < name.length() - 1) && name.charAt(i) == '$');}return false;}/*** Make the given field accessible, explicitly setting it accessible if* necessary. The {@code setAccessible(true)} method is only called* when actually necessary, to avoid unnecessary conflicts with a JVM* SecurityManager (if active).* @param field the field to make accessible* @see java.lang.reflect.Field#setAccessible*/@SuppressWarnings("deprecation")  // on JDK 9public static void makeAccessible(Field field) {if ((!Modifier.isPublic(field.getModifiers()) ||!Modifier.isPublic(field.getDeclaringClass().getModifiers()) ||Modifier.isFinal(field.getModifiers())) && !field.isAccessible()) {field.setAccessible(true);}}/*** Make the given method accessible, explicitly setting it accessible if* necessary. The {@code setAccessible(true)} method is only called* when actually necessary, to avoid unnecessary conflicts with a JVM* SecurityManager (if active).* @param method the method to make accessible* @see java.lang.reflect.Method#setAccessible*/@SuppressWarnings("deprecation")  // on JDK 9public static void makeAccessible(Method method) {if ((!Modifier.isPublic(method.getModifiers()) ||!Modifier.isPublic(method.getDeclaringClass().getModifiers())) && !method.isAccessible()) {method.setAccessible(true);}}/*** Make the given constructor accessible, explicitly setting it accessible* if necessary. The {@code setAccessible(true)} method is only called* when actually necessary, to avoid unnecessary conflicts with a JVM* SecurityManager (if active).* @param ctor the constructor to make accessible* @see java.lang.reflect.Constructor#setAccessible*/@SuppressWarnings("deprecation")  // on JDK 9public static void makeAccessible(Constructor<?> ctor) {if ((!Modifier.isPublic(ctor.getModifiers()) ||!Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) && !ctor.isAccessible()) {ctor.setAccessible(true);}}/*** Obtain an accessible constructor for the given class and parameters.* @param clazz the clazz to check* @param parameterTypes the parameter types of the desired constructor* @return the constructor reference* @throws NoSuchMethodException if no such constructor exists* @since 5.0*/public static <T> Constructor<T> accessibleConstructor(Class<T> clazz, Class<?>... parameterTypes)throws NoSuchMethodException {Constructor<T> ctor = clazz.getDeclaredConstructor(parameterTypes);makeAccessible(ctor);return ctor;}/*** Perform the given callback operation on all matching methods of the given* class, as locally declared or equivalent thereof (such as default methods* on Java 8 based interfaces that the given class implements).* @param clazz the class to introspect* @param mc the callback to invoke for each method* @throws IllegalStateException if introspection fails* @since 4.2* @see #doWithMethods*/public static void doWithLocalMethods(Class<?> clazz, MethodCallback mc) {Method[] methods = getDeclaredMethods(clazz);for (Method method : methods) {try {mc.doWith(method);}catch (IllegalAccessException ex) {throw new IllegalStateException("Not allowed to access method '" + method.getName() + "': " + ex);}}}/*** Perform the given callback operation on all matching methods of the given* class and superclasses.* <p>The same named method occurring on subclass and superclass will appear* twice, unless excluded by a {@link MethodFilter}.* @param clazz the class to introspect* @param mc the callback to invoke for each method* @throws IllegalStateException if introspection fails* @see #doWithMethods(Class, MethodCallback, MethodFilter)*/public static void doWithMethods(Class<?> clazz, MethodCallback mc) {doWithMethods(clazz, mc, null);}/*** Perform the given callback operation on all matching methods of the given* class and superclasses (or given interface and super-interfaces).* <p>The same named method occurring on subclass and superclass will appear* twice, unless excluded by the specified {@link MethodFilter}.* @param clazz the class to introspect* @param mc the callback to invoke for each method* @param mf the filter that determines the methods to apply the callback to* @throws IllegalStateException if introspection fails*/public static void doWithMethods(Class<?> clazz, MethodCallback mc, @Nullable MethodFilter mf) {// Keep backing up the inheritance hierarchy.Method[] methods = getDeclaredMethods(clazz);for (Method method : methods) {if (mf != null && !mf.matches(method)) {continue;}try {mc.doWith(method);}catch (IllegalAccessException ex) {throw new IllegalStateException("Not allowed to access method '" + method.getName() + "': " + ex);}}if (clazz.getSuperclass() != null) {doWithMethods(clazz.getSuperclass(), mc, mf);}else if (clazz.isInterface()) {for (Class<?> superIfc : clazz.getInterfaces()) {doWithMethods(superIfc, mc, mf);}}}/*** Get all declared methods on the leaf class and all superclasses.* Leaf class methods are included first.* @param leafClass the class to introspect* @throws IllegalStateException if introspection fails*/public static Method[] getAllDeclaredMethods(Class<?> leafClass) {final List<Method> methods = new ArrayList<>(32);doWithMethods(leafClass, methods::add);return methods.toArray(new Method[0]);}/*** Get the unique set of declared methods on the leaf class and all superclasses.* Leaf class methods are included first and while traversing the superclass hierarchy* any methods found with signatures matching a method already included are filtered out.* @param leafClass the class to introspect* @throws IllegalStateException if introspection fails*/public static Method[] getUniqueDeclaredMethods(Class<?> leafClass) {final List<Method> methods = new ArrayList<>(32);doWithMethods(leafClass, method -> {boolean knownSignature = false;Method methodBeingOverriddenWithCovariantReturnType = null;for (Method existingMethod : methods) {if (method.getName().equals(existingMethod.getName()) &&Arrays.equals(method.getParameterTypes(), existingMethod.getParameterTypes())) {// Is this a covariant return type situation?if (existingMethod.getReturnType() != method.getReturnType() &&existingMethod.getReturnType().isAssignableFrom(method.getReturnType())) {methodBeingOverriddenWithCovariantReturnType = existingMethod;}else {knownSignature = true;}break;}}if (methodBeingOverriddenWithCovariantReturnType != null) {methods.remove(methodBeingOverriddenWithCovariantReturnType);}if (!knownSignature && !isCglibRenamedMethod(method)) {methods.add(method);}});return methods.toArray(new Method[0]);}/*** This variant retrieves {@link Class#getDeclaredMethods()} from a local cache* in order to avoid the JVM's SecurityManager check and defensive array copying.* In addition, it also includes Java 8 default methods from locally implemented* interfaces, since those are effectively to be treated just like declared methods.* @param clazz the class to introspect* @return the cached array of methods* @throws IllegalStateException if introspection fails* @see Class#getDeclaredMethods()*/private static Method[] getDeclaredMethods(Class<?> clazz) {Assert.notNull(clazz, "Class must not be null");Method[] result = declaredMethodsCache.get(clazz);if (result == null) {try {Method[] declaredMethods = clazz.getDeclaredMethods();List<Method> defaultMethods = findConcreteMethodsOnInterfaces(clazz);if (defaultMethods != null) {result = new Method[declaredMethods.length + defaultMethods.size()];System.arraycopy(declaredMethods, 0, result, 0, declaredMethods.length);int index = declaredMethods.length;for (Method defaultMethod : defaultMethods) {result[index] = defaultMethod;index++;}}else {result = declaredMethods;}declaredMethodsCache.put(clazz, (result.length == 0 ? NO_METHODS : result));}catch (Throwable ex) {throw new IllegalStateException("Failed to introspect Class [" + clazz.getName() +"] from ClassLoader [" + clazz.getClassLoader() + "]", ex);}}return result;}@Nullableprivate static List<Method> findConcreteMethodsOnInterfaces(Class<?> clazz) {List<Method> result = null;for (Class<?> ifc : clazz.getInterfaces()) {for (Method ifcMethod : ifc.getMethods()) {if (!Modifier.isAbstract(ifcMethod.getModifiers())) {if (result == null) {result = new ArrayList<>();}result.add(ifcMethod);}}}return result;}/*** Invoke the given callback on all locally declared fields in the given class.* @param clazz the target class to analyze* @param fc the callback to invoke for each field* @throws IllegalStateException if introspection fails* @since 4.2* @see #doWithFields*/public static void doWithLocalFields(Class<?> clazz, FieldCallback fc) {for (Field field : getDeclaredFields(clazz)) {try {fc.doWith(field);}catch (IllegalAccessException ex) {throw new IllegalStateException("Not allowed to access field '" + field.getName() + "': " + ex);}}}/*** Invoke the given callback on all fields in the target class, going up the* class hierarchy to get all declared fields.* @param clazz the target class to analyze* @param fc the callback to invoke for each field* @throws IllegalStateException if introspection fails*/public static void doWithFields(Class<?> clazz, FieldCallback fc) {doWithFields(clazz, fc, null);}/*** Invoke the given callback on all fields in the target class, going up the* class hierarchy to get all declared fields.* @param clazz the target class to analyze* @param fc the callback to invoke for each field* @param ff the filter that determines the fields to apply the callback to* @throws IllegalStateException if introspection fails*/public static void doWithFields(Class<?> clazz, FieldCallback fc, @Nullable FieldFilter ff) {// Keep backing up the inheritance hierarchy.Class<?> targetClass = clazz;do {Field[] fields = getDeclaredFields(targetClass);for (Field field : fields) {if (ff != null && !ff.matches(field)) {continue;}try {fc.doWith(field);}catch (IllegalAccessException ex) {throw new IllegalStateException("Not allowed to access field '" + field.getName() + "': " + ex);}}targetClass = targetClass.getSuperclass();}while (targetClass != null && targetClass != Object.class);}/*** This variant retrieves {@link Class#getDeclaredFields()} from a local cache* in order to avoid the JVM's SecurityManager check and defensive array copying.* @param clazz the class to introspect* @return the cached array of fields* @throws IllegalStateException if introspection fails* @see Class#getDeclaredFields()*/private static Field[] getDeclaredFields(Class<?> clazz) {Assert.notNull(clazz, "Class must not be null");Field[] result = declaredFieldsCache.get(clazz);if (result == null) {try {result = clazz.getDeclaredFields();declaredFieldsCache.put(clazz, (result.length == 0 ? NO_FIELDS : result));}catch (Throwable ex) {throw new IllegalStateException("Failed to introspect Class [" + clazz.getName() +"] from ClassLoader [" + clazz.getClassLoader() + "]", ex);}}return result;}/*** Given the source object and the destination, which must be the same class* or a subclass, copy all fields, including inherited fields. Designed to* work on objects with public no-arg constructors.* @throws IllegalStateException if introspection fails*/public static void shallowCopyFieldState(final Object src, final Object dest) {Assert.notNull(src, "Source for field copy cannot be null");Assert.notNull(dest, "Destination for field copy cannot be null");if (!src.getClass().isAssignableFrom(dest.getClass())) {throw new IllegalArgumentException("Destination class [" + dest.getClass().getName() +"] must be same or subclass as source class [" + src.getClass().getName() + "]");}doWithFields(src.getClass(), field -> {makeAccessible(field);Object srcValue = field.get(src);field.set(dest, srcValue);}, COPYABLE_FIELDS);}/*** Clear the internal method/field cache.* @since 4.2.4*/public static void clearCache() {declaredMethodsCache.clear();declaredFieldsCache.clear();}/*** Action to take on each method.*/@FunctionalInterfacepublic interface MethodCallback {/*** Perform an operation using the given method.* @param method the method to operate on*/void doWith(Method method) throws IllegalArgumentException, IllegalAccessException;}/*** Callback optionally used to filter methods to be operated on by a method callback.*/@FunctionalInterfacepublic interface MethodFilter {/*** Determine whether the given method matches.* @param method the method to check*/boolean matches(Method method);}/*** Callback interface invoked on each field in the hierarchy.*/@FunctionalInterfacepublic interface FieldCallback {/*** Perform an operation using the given field.* @param field the field to operate on*/void doWith(Field field) throws IllegalArgumentException, IllegalAccessException;}/*** Callback optionally used to filter fields to be operated on by a field callback.*/@FunctionalInterfacepublic interface FieldFilter {/*** Determine whether the given field matches.* @param field the field to check*/boolean matches(Field field);}}