Spring 中一个常用的反射类库ReflectionUtils
在项目中部分方法采用反射，通过类访问类的属性，通过类反问方法，通过属性访问方法。以及常用异常的处理在等可以使用反射出处理。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 <code>name</code>. 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</code> 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 <code>name</code> 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</code> if type is specified)* @param type the type of the field (may be <code>null</code> if name is specified)* @return the corresponding Field object, or <code>null</code> 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; 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* <code>value</code>. 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</code>*/ 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，获取的对象中字段的值* 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.* <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*/ 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 <code>Object</code>.* <p>Returns <code>null</code> 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</code> if none found*/ public static Method findMethod(Class clazz, String name) {return findMethod(clazz, name, new Class); }/**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 <code>Object</code>.* <p>Returns <code>null</code> 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</code> to indicate any signature)* @return the Method object, or <code>null</code> 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; 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 <code>null</code> 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[])*/ 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 <code>null</code>* 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</code>)* @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 <code>null</code>)* @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.* <p>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.* <p>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* <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 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* <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 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 <code>true</code> if the exception can be thrown as-is;* <code>false</code> 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; 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 == 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 <code>setAccessible(true)</code> 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 <code>setAccessible(true)</code> 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 <code>setAccessible(true)</code> 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.* <p>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.* <p>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)) { continue; } try { mc.doWith(methods); } catch (IllegalAccessException ex) { throw new IllegalStateException( "Shouldn't be illegal to access method '" + methods.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); }/**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)) { continue; } try { fc.doWith(fields); } catch (IllegalAccessException ex) { throw new IllegalStateException( "Shouldn't be illegal to access field '" + fields.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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