spring的反射工具类ReflectionUtils

spring的反射工具类ReflectionUtils

spring提供的ReflectionUtils可以简化项目中反射代码的复杂性在项目中如果使用最原始的方法来开发反射的功能的话肯能会比较复杂，需要处理一大堆异常以及访问权限等问题。spring中提供了ReflectionUtils这个反射的工具类

public abstract class ReflectionUtils {/**根据类和属性名称查找属性字段* Attempt to find a {@link Field field} on the supplied {@link Class} with* the supplied 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 null if not found*/public static Field findField(Class clazz, String name) {return findField(clazz, name, null);}/**根据类和属性名称查找属性字段* Attempt to find a {@link Field field} on the supplied {@link Class} with* the supplied 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 null if type is specified)* @param type the type of the field (may be null if name is specified)* @return the corresponding Field object, or null if not found*/public static Field findField(Class clazz, String name, 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.equals(searchType) && searchType != null) {Field[] fields = searchType.getDeclaredFields();for (int i = 0; i < fields.length; i++) {Field field = fields[i];if ((name == null || name.equals(field.getName()))&& (type == null || type.equals(field.getType()))) {return field;}}searchType = searchType.getSuperclass();}return null;}/**根据属性字段和对象，设置对象的值* Set the field represented by the supplied {@link Field field object} on* the specified {@link Object target object} to the specified* value. In accordance with* {@link Field#set(Object, Object)} semantics, the new value is* automatically unwrapped if the underlying field has a primitive type.*

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 null*/public static void setField(Field field, Object target, Object value) {try {field.set(target, value);}catch (IllegalAccessException ex) {handleReflectionException(ex);throw new IllegalStateException("Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());}}/**根据属性字段和对象，获取对象中字段的值* 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.*

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*/public static Object getField(Field field, Object target) {try {return field.get(target);}catch (IllegalAccessException ex) {handleReflectionException(ex);throw new IllegalStateException("Unexpected reflection exception - " + ex.getClass().getName() + ": " + ex.getMessage());}}/**根据类，方法名称和参数类型查找方法* Attempt to find a {@link Method} on the supplied class with the supplied name* and no parameters. Searches all superclasses up to Object.*

Returns 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 null if none found*/public static Method findMethod(Class clazz, String name) {return findMethod(clazz, name, new Class[0]);}/**根据类，方法名称和参数类型查找方法* Attempt to find a {@link Method} on the supplied class with the supplied name* and parameter types. Searches all superclasses up to Object.*

Returns 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 null to indicate any signature)* @return the Method object, or null if none found*/public static Method findMethod(Class clazz, String name, Class[] paramTypes) {Assert.notNull(clazz, "Class must not be null");Assert.notNull(name, "Method name must not be null");Class searchType = clazz;while (!Object.class.equals(searchType) && searchType != null) {Method[] methods = (searchType.isInterface() ? searchType.getMethods() : searchType.getDeclaredMethods());for (int i = 0; i < methods.length; i++) {Method method = methods[i];if (name.equals(method.getName()) &&(paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {return method;}}searchType = searchType.getSuperclass();}return null;}/**调用方法的应用* Invoke the specified {@link Method} against the supplied target object* with no arguments. The target object can be null when* invoking a static {@link Method}.*

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[])*/public static Object invokeMethod(Method method, Object target) {return invokeMethod(method, target, null);}/**调用方法的应用* Invoke the specified {@link Method} against the supplied target object* with the supplied arguments. The target object can be null* when invoking a static {@link Method}.*

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 null)* @return the invocation result, if any*/public static Object invokeMethod(Method method, Object target, 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[])*/public static Object invokeJdbcMethod(Method method, Object target) throws SQLException {return invokeJdbcMethod(method, target, null);}/*** 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 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[])*/public static Object invokeJdbcMethod(Method method, Object target, 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");}/**************************************************************** 处理异常的方法****************************************************************//** 使用反射处理异常的将异常信息输出但不抛出方法以外* Handle the given reflection exception. Should only be called if* no checked exception is expected to be thrown by the target method.*

Throws the underlying RuntimeException or Error in case of an* InvocationTargetException with such a root cause. Throws an* IllegalStateException with an appropriate message else.* @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;}handleUnexpectedException(ex);}/** * Handle the given invocation target exception. Should only be called if* no checked exception is expected to be thrown by the target method.*

Throws the underlying RuntimeException or Error in case of such* a root cause. Throws an IllegalStateException else.* @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* target exception of an {@link InvocationTargetException}.* Should only be called if no checked exception is expected to be thrown by* the target method.*

Rethrows the underlying exception cast to an {@link RuntimeException}* or {@link Error} if appropriate; otherwise, throws an* {@link IllegalStateException}.* @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;}handleUnexpectedException(ex);}/*** Rethrow the given {@link Throwable exception}, which is presumably the* target exception of an {@link InvocationTargetException}.* Should only be called if no checked exception is expected to be thrown by* the target method.*

Rethrows the underlying exception cast to an {@link Exception} or* {@link Error} if appropriate; otherwise, throws an* {@link IllegalStateException}.* @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;}handleUnexpectedException(ex);}/*** Throws an IllegalStateException with the given exception as root cause.* @param ex the unexpected exception*/private static void handleUnexpectedException(Throwable ex) {// Needs to avoid the chained constructor for JDK 1.4 compatibility.IllegalStateException isex = new IllegalStateException("Unexpected exception thrown");isex.initCause(ex);throw isex;}/*** 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 true if the exception can be thrown as-is;* 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 (int i = 0; i < declaredExceptions.length; i++) {Class declaredException = declaredExceptions[i];if (declaredException.isAssignableFrom(exceptionType)) {return true;}}return false;}/**************************************************************** 判断方法，属性字段等的修饰符的方法*************************************************************//*** 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*/public static boolean isEqualsMethod(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(Method method) {return (method != null && method.getName().equals("hashCode") &&method.getParameterTypes().length == 0);}/*** Determine whether the given method is a "toString" method.* @see java.lang.Object#toString()*/public static boolean isToStringMethod(Method method) {return (method != null && method.getName().equals("toString") &&method.getParameterTypes().length == 0);}/** 判断一个属性是否可以访问的方法 * Make the given field accessible, explicitly setting it accessible if necessary.* The 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*/public static void makeAccessible(Field field) {if (!Modifier.isPublic(field.getModifiers()) ||!Modifier.isPublic(field.getDeclaringClass().getModifiers())) {field.setAccessible(true);}}/** 判断一个方法是否可以访问的方法 * Make the given method accessible, explicitly setting it accessible if necessary.* The 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*/public static void makeAccessible(Method method) {if (!Modifier.isPublic(method.getModifiers()) ||!Modifier.isPublic(method.getDeclaringClass().getModifiers())) {method.setAccessible(true);}}/** 判断一个构造函数是否可以访问的方法 * Make the given constructor accessible, explicitly setting it accessible if necessary.* The 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*/public static void makeAccessible(Constructor ctor) {if (!Modifier.isPublic(ctor.getModifiers()) ||!Modifier.isPublic(ctor.getDeclaringClass().getModifiers())) {ctor.setAccessible(true);}}/*** Perform the given callback operation on all matching methods of the* given class and superclasses.*

The same named method occurring on subclass and superclass will* appear twice, unless excluded by a {@link MethodFilter}.* @param targetClass class to start looking at* @param mc the callback to invoke for each method* @see #doWithMethods(Class, MethodCallback, MethodFilter)*/public static void doWithMethods(Class targetClass, MethodCallback mc) throws IllegalArgumentException {doWithMethods(targetClass, mc, null);}/*** Perform the given callback operation on all matching methods of the* given class and superclasses.*

The same named method occurring on subclass and superclass will* appear twice, unless excluded by the specified {@link MethodFilter}.* @param targetClass class to start looking at* @param mc the callback to invoke for each method* @param mf the filter that determines the methods to apply the callback to*/public static void doWithMethods(Class targetClass, MethodCallback mc, MethodFilter mf)throws IllegalArgumentException {// Keep backing up the inheritance hierarchy.do {Method[] methods = targetClass.getDeclaredMethods();for (int i = 0; i < methods.length; i++) {if (mf != null && !mf.matches(methods[i])) {continue;}try {mc.doWith(methods[i]);}catch (IllegalAccessException ex) {throw new IllegalStateException("Shouldn't be illegal to access method '" + methods[i].getName() + "': " + ex);}}targetClass = targetClass.getSuperclass();}while (targetClass != null);}/**获取类的所有的方法的* Get all declared methods on the leaf class and all superclasses.* Leaf class methods are included first.*/public static Method[] getAllDeclaredMethods(Class leafClass) throws IllegalArgumentException {final List list = new ArrayList(32);doWithMethods(leafClass, new MethodCallback() {public void doWith(Method method) {list.add(method);}});return (Method[]) list.toArray(new Method[list.size()]);}/**调用字段时执行的回调的方法* Invoke the given callback on all fields in the target class,* going up the class hierarchy to get all declared fields.* @param targetClass the target class to analyze* @param fc the callback to invoke for each field*/public static void doWithFields(Class targetClass, FieldCallback fc) throws IllegalArgumentException {doWithFields(targetClass, fc, null);}/**调用字段时执行的回调的并过滤的方法* Invoke the given callback on all fields in the target class,* going up the class hierarchy to get all declared fields.* @param targetClass 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*/public static void doWithFields(Class targetClass, FieldCallback fc, FieldFilter ff)throws IllegalArgumentException {// Keep backing up the inheritance hierarchy.do {// Copy each field declared on this class unless it's static or file.Field[] fields = targetClass.getDeclaredFields();for (int i = 0; i < fields.length; i++) {// Skip static and final fields.if (ff != null && !ff.matches(fields[i])) {continue;}try {fc.doWith(fields[i]);}catch (IllegalAccessException ex) {throw new IllegalStateException("Shouldn't be illegal to access field '" + fields[i].getName() + "': " + ex);}}targetClass = targetClass.getSuperclass();}while (targetClass != null && targetClass != Object.class);}/**用于对象的拷贝的方法（类必须是同一类或子类）* 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 IllegalArgumentException if the arguments are incompatible*/public static void shallowCopyFieldState(final Object src, final Object dest) throws IllegalArgumentException {if (src == null) {throw new IllegalArgumentException("Source for field copy cannot be null");}if (dest == null) {throw new IllegalArgumentException("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(), new FieldCallback() {public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {makeAccessible(field);Object srcValue = field.get(src);field.set(dest, srcValue);}}, COPYABLE_FIELDS);}/*** Action to take on each method.*/public static 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 method fields to be operated on by a method callback.*/public static 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.*/public static 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.*/public static interface FieldFilter {/*** Determine whether the given field matches.* @param field the field to check*/boolean matches(Field field);}/*** Pre-built FieldFilter that matches all non-static, non-final fields.*/public static FieldFilter COPYABLE_FIELDS = new FieldFilter() {public boolean matches(Field field) {return !(Modifier.isStatic(field.getModifiers()) ||Modifier.isFinal(field.getModifiers()));}};}

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