一、前言

基于spring-beans(4.1.4)的工具類org.springframework.beans.BeanUtils對注入spring對象按照Class實例化instantiateClass、class對象方法名稱methodName查找findMethod、屬性查找對于class類信息findPropertyType、對象屬性復制copyProperties等常用操作，具體如下源碼所示。

二、源碼說明package?org.springframework.beans;@b@@b@import?java.beans.PropertyDescriptor;@b@import?java.beans.PropertyEditor;@b@import?java.lang.reflect.Constructor;@b@import?java.lang.reflect.InvocationTargetException;@b@import?java.lang.reflect.Method;@b@import?java.lang.reflect.Modifier;@b@import?java.net.URI;@b@import?java.net.URL;@b@import?java.util.Arrays;@b@import?java.util.Collections;@b@import?java.util.Date;@b@import?java.util.List;@b@import?java.util.Locale;@b@import?java.util.Set;@b@import?org.apache.commons.logging.Log;@b@import?org.apache.commons.logging.LogFactory;@b@import?org.springframework.core.MethodParameter;@b@import?org.springframework.util.Assert;@b@import?org.springframework.util.ClassUtils;@b@import?org.springframework.util.ConcurrentReferenceHashMap;@b@import?org.springframework.util.ReflectionUtils;@b@import?org.springframework.util.StringUtils;@b@@b@public?abstract?class?BeanUtils@b@{@b@??private?static?final?Log?logger?=?LogFactory.getLog(BeanUtils.class);@b@??private?static?final?Set>?unknownEditorTypes?=?Collections.newSetFromMap(new?ConcurrentReferenceHashMap(64));@b@@b@??public?static??T?instantiate(Class?clazz)@b@????throws?BeanInstantiationException@b@??{@b@????Assert.notNull(clazz,?"Class?must?not?be?null");@b@????if?(clazz.isInterface())@b@??????throw?new?BeanInstantiationException(clazz,?"Specified?class?is?an?interface");@b@????try@b@????{@b@??????return?clazz.newInstance();@b@????}@b@????catch?(InstantiationException?ex)?{@b@??????throw?new?BeanInstantiationException(clazz,?"Is?it?an?abstract?class?",?ex);@b@????}@b@????catch?(IllegalAccessException?ex)?{@b@??????throw?new?BeanInstantiationException(clazz,?"Is?the?constructor?accessible?",?ex);@b@????}@b@??}@b@@b@??public?static??T?instantiateClass(Class?clazz)@b@????throws?BeanInstantiationException@b@??{@b@????Assert.notNull(clazz,?"Class?must?not?be?null");@b@????if?(clazz.isInterface())@b@??????throw?new?BeanInstantiationException(clazz,?"Specified?class?is?an?interface");@b@????try@b@????{@b@??????return?instantiateClass(clazz.getDeclaredConstructor(new?Class[0]),?new?Object[0]);@b@????}@b@????catch?(NoSuchMethodException?ex)?{@b@??????throw?new?BeanInstantiationException(clazz,?"No?default?constructor?found",?ex);@b@????}@b@??}@b@@b@??public?static??T?instantiateClass(Class>?clazz,?Class?assignableTo)@b@????throws?BeanInstantiationException@b@??{@b@????Assert.isAssignable(assignableTo,?clazz);@b@????return?instantiateClass(clazz);@b@??}@b@@b@??public?static??T?instantiateClass(Constructor?ctor,?Object[]?args)@b@????throws?BeanInstantiationException@b@??{@b@????Assert.notNull(ctor,?"Constructor?must?not?be?null");@b@????try?{@b@??????ReflectionUtils.makeAccessible(ctor);@b@??????return?ctor.newInstance(args);@b@????}@b@????catch?(InstantiationException?ex)?{@b@??????throw?new?BeanInstantiationException(ctor.getDeclaringClass(),?"Is?it?an?abstract?class?",?ex);@b@????}@b@????catch?(IllegalAccessException?ex)@b@????{@b@??????throw?new?BeanInstantiationException(ctor.getDeclaringClass(),?"Is?the?constructor?accessible?",?ex);@b@????}@b@????catch?(IllegalArgumentException?ex)@b@????{@b@??????throw?new?BeanInstantiationException(ctor.getDeclaringClass(),?"Illegal?arguments?for?constructor",?ex);@b@????}@b@????catch?(InvocationTargetException?ex)@b@????{@b@??????throw?new?BeanInstantiationException(ctor.getDeclaringClass(),?"Constructor?threw?exception",?ex@b@????????.getTargetException());@b@????}@b@??}@b@@b@??public?static?Method?findMethod(Class>?clazz,?String?methodName,?Class>[]?paramTypes)@b@??{@b@????try@b@????{@b@??????return?clazz.getMethod(methodName,?paramTypes);@b@????}?catch?(NoSuchMethodException?ex)?{@b@????}@b@????return?findDeclaredMethod(clazz,?methodName,?paramTypes);@b@??}@b@@b@??public?static?Method?findDeclaredMethod(Class>?clazz,?String?methodName,?Class>[]?paramTypes)@b@??{@b@????try@b@????{@b@??????return?clazz.getDeclaredMethod(methodName,?paramTypes);@b@????}@b@????catch?(NoSuchMethodException?ex)?{@b@??????if?(clazz.getSuperclass()?!=?null)@b@????????return?findDeclaredMethod(clazz.getSuperclass(),?methodName,?paramTypes);@b@????}@b@????return?null;@b@??}@b@@b@??public?static?Method?findMethodWithMinimalParameters(Class>?clazz,?String?methodName)@b@????throws?IllegalArgumentException@b@??{@b@????Method?targetMethod?=?findMethodWithMinimalParameters(clazz.getMethods(),?methodName);@b@????if?(targetMethod?==?null)@b@??????targetMethod?=?findDeclaredMethodWithMinimalParameters(clazz,?methodName);@b@@b@????return?targetMethod;@b@??}@b@@b@??public?static?Method?findDeclaredMethodWithMinimalParameters(Class>?clazz,?String?methodName)@b@????throws?IllegalArgumentException@b@??{@b@????Method?targetMethod?=?findMethodWithMinimalParameters(clazz.getDeclaredMethods(),?methodName);@b@????if?((targetMethod?==?null)?&&?(clazz.getSuperclass()?!=?null))@b@??????targetMethod?=?findDeclaredMethodWithMinimalParameters(clazz.getSuperclass(),?methodName);@b@@b@????return?targetMethod;@b@??}@b@@b@??public?static?Method?findMethodWithMinimalParameters(Method[]?methods,?String?methodName)@b@????throws?IllegalArgumentException@b@??{@b@????Method?targetMethod?=?null;@b@????int?numMethodsFoundWithCurrentMinimumArgs?=?0;@b@????Method[]?arrayOfMethod?=?methods;?int?i?=?arrayOfMethod.length;?for?(int?j?=?0;?j??1)?{@b@??????throw?new?IllegalArgumentException("Cannot?resolve?method?'"?+?methodName?+?"'?to?a?unique?method.?Attempted?to?resolve?to?overloaded?method?with?"?+?"the?least?number?of?parameters,?but?there?were?"?+?numMethodsFoundWithCurrentMinimumArgs?+?"?candidates.");@b@????}@b@@b@????return?targetMethod;@b@??}@b@@b@??public?static?Method?resolveSignature(String?signature,?Class>?clazz)@b@??{@b@????Assert.hasText(signature,?"'signature'?must?not?be?empty");@b@????Assert.notNull(clazz,?"Class?must?not?be?null");@b@????int?firstParen?=?signature.indexOf("(");@b@????int?lastParen?=?signature.indexOf(")");@b@????if?((firstParen?>?-1)?&&?(lastParen?==?-1))?{@b@??????throw?new?IllegalArgumentException("Invalid?method?signature?'"?+?signature?+?"':?expected?closing?')'?for?args?list");@b@????}@b@@b@????if?((lastParen?>?-1)?&&?(firstParen?==?-1))?{@b@??????throw?new?IllegalArgumentException("Invalid?method?signature?'"?+?signature?+?"':?expected?opening?'('?for?args?list");@b@????}@b@@b@????if?((firstParen?==?-1)?&&?(lastParen?==?-1))?{@b@??????return?findMethodWithMinimalParameters(clazz,?signature);@b@????}@b@@b@????String?methodName?=?signature.substring(0,?firstParen);@b@@b@????String[]?parameterTypeNames?=?StringUtils.commaDelimitedListToStringArray(signature@b@??????.substring(firstParen?+?1,?lastParen));@b@@b@????Class[]?parameterTypes?=?new?Class[parameterTypeNames.length];@b@????for?(int?i?=?0;?i??clazz)@b@????throws?BeansException@b@??{@b@????CachedIntrospectionResults?cr?=?CachedIntrospectionResults.forClass(clazz);@b@????return?cr.getPropertyDescriptors();@b@??}@b@@b@??public?static?PropertyDescriptor?getPropertyDescriptor(Class>?clazz,?String?propertyName)@b@????throws?BeansException@b@??{@b@????CachedIntrospectionResults?cr?=?CachedIntrospectionResults.forClass(clazz);@b@????return?cr.getPropertyDescriptor(propertyName);@b@??}@b@@b@??public?static?PropertyDescriptor?findPropertyForMethod(Method?method)@b@????throws?BeansException@b@??{@b@????return?findPropertyForMethod(method,?method.getDeclaringClass());@b@??}@b@@b@??public?static?PropertyDescriptor?findPropertyForMethod(Method?method,?Class>?clazz)@b@????throws?BeansException@b@??{@b@????Assert.notNull(method,?"Method?must?not?be?null");@b@????PropertyDescriptor[]?pds?=?getPropertyDescriptors(clazz);@b@????PropertyDescriptor[]?arrayOfPropertyDescriptor1?=?pds;?int?i?=?arrayOfPropertyDescriptor1.length;?for?(int?j?=?0;?j??targetType)@b@??{@b@????if?((targetType?==?null)?||?(targetType.isArray())?||?(unknownEditorTypes.contains(targetType)))@b@??????return?null;@b@@b@????ClassLoader?cl?=?targetType.getClassLoader();@b@????if?(cl?==?null)@b@??????try?{@b@????????cl?=?ClassLoader.getSystemClassLoader();@b@????????if?(cl?==?null)@b@??????????return?null;@b@@b@??????}@b@??????catch?(Throwable?ex)@b@??????{@b@????????if?(logger.isDebugEnabled())@b@??????????logger.debug("Could?not?access?system?ClassLoader:?"?+?ex);@b@@b@????????return?null;@b@??????}@b@@b@????String?editorName?=?targetType.getName()?+?"Editor";@b@????try?{@b@??????Class?editorClass?=?cl.loadClass(editorName);@b@??????if?(!(PropertyEditor.class.isAssignableFrom(editorClass)))?{@b@????????if?(logger.isWarnEnabled())?{@b@??????????logger.warn("Editor?class?["?+?editorName?+?"]?does?not?implement?[java.beans.PropertyEditor]?interface");@b@????????}@b@@b@????????unknownEditorTypes.add(targetType);@b@????????return?null;@b@??????}@b@??????return?((PropertyEditor)instantiateClass(editorClass));@b@????}@b@????catch?(ClassNotFoundException?ex)?{@b@??????if?(logger.isDebugEnabled())@b@????????logger.debug("No?property?editor?["?+?editorName?+?"]?found?for?type?"?+?targetType@b@??????????.getName()?+?"?according?to?'Editor'?suffix?convention");@b@@b@??????unknownEditorTypes.add(targetType);?}@b@????return?null;@b@??}@b@@b@??public?static?Class>?findPropertyType(String?propertyName,?Class>[]?beanClasses)@b@??{@b@????Class[]?arrayOfClass;@b@????int?j;@b@????if?(beanClasses?!=?null)?{@b@??????arrayOfClass?=?beanClasses;?int?i?=?arrayOfClass.length;?for?(j?=?0;?j??clazz)@b@??{@b@????Assert.notNull(clazz,?"Class?must?not?be?null");@b@????return?((isSimpleValueType(clazz))?||?((clazz.isArray())?&&?(isSimpleValueType(clazz.getComponentType()))));@b@??}@b@@b@??public?static?boolean?isSimpleValueType(Class>?clazz)@b@??{@b@????return?((ClassUtils.isPrimitiveOrWrapper(clazz))?||?(clazz.isEnum())?||?@b@??????(CharSequence.class@b@??????.isAssignableFrom(clazz))?||?@b@??????(Number.class@b@??????.isAssignableFrom(clazz))?||?@b@??????(Date.class@b@??????.isAssignableFrom(clazz))?||?@b@??????(clazz@b@??????.equals(URI.class))?||?@b@??????(clazz.equals(URL.class))?||?@b@??????(clazz@b@??????.equals(Locale.class))?||?@b@??????(clazz.equals(Class.class)));@b@??}@b@@b@??public?static?void?copyProperties(Object?source,?Object?target)@b@????throws?BeansException@b@??{@b@????copyProperties(source,?target,?null,?(String[])null);@b@??}@b@@b@??public?static?void?copyProperties(Object?source,?Object?target,?Class>?editable)@b@????throws?BeansException@b@??{@b@????copyProperties(source,?target,?editable,?(String[])null);@b@??}@b@@b@??public?static?void?copyProperties(Object?source,?Object?target,?String[]?ignoreProperties)@b@????throws?BeansException@b@??{@b@????copyProperties(source,?target,?null,?ignoreProperties);@b@??}@b@@b@??private?static?void?copyProperties(Object?source,?Object?target,?Class>?editable,?String[]?ignoreProperties)@b@????throws?BeansException@b@??{@b@????Assert.notNull(source,?"Source?must?not?be?null");@b@????Assert.notNull(target,?"Target?must?not?be?null");@b@@b@????Class?actualEditable?=?target.getClass();@b@????if?(editable?!=?null)?{@b@??????if?(!(editable.isInstance(target)))@b@??????{@b@????????throw?new?IllegalArgumentException("Target?class?["?+?target.getClass().getName()?+?"]?not?assignable?to?Editable?class?["?+?editable@b@??????????.getName()?+?"]");@b@??????}@b@??????actualEditable?=?editable;@b@????}@b@????PropertyDescriptor[]?targetPds?=?getPropertyDescriptors(actualEditable);@b@????List?ignoreList?=?(ignoreProperties?!=?null)???Arrays.asList(ignoreProperties)?:?null;@b@@b@????PropertyDescriptor[]?arrayOfPropertyDescriptor1?=?targetPds;?int?i?=?arrayOfPropertyDescriptor1.length;?for?(int?j?=?0;?j?

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