ReflectHelper 反射(Method,Class的应用一)

package com.songbx;import java.lang.reflect.Constructor;import java.lang.reflect.Member;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import org.hibernate.AssertionFailure;import org.hibernate.PropertyNotFoundException;import org.hibernate.type.PrimitiveType;import org.hibernate.type.Type;public class ReflectHelper {private static final Class[] NO_CLASSES = new Class[0];private static final Class[] OBJECT = new Class[] { Object.class };private static final Method OBJECT_EQUALS;private static final Class[] NO_PARAM = new Class[] { };private static final Method OBJECT_HASHCODE;static {Method eq;Method hash;try {eq = Object.class.getMethod("equals", OBJECT);hash = Object.class.getMethod("hashCode", NO_PARAM);}catch (Exception e) {throw new AssertionFailure("Could not find Object.equals() or Object.hashCode()", e);}OBJECT_EQUALS = eq;OBJECT_HASHCODE = hash;}//是否覆盖了equals方法public static boolean overridesEquals(Class clazz) {Method equals;try {equals = clazz.getMethod("equals", OBJECT);}catch (NoSuchMethodException nsme) {return false; //its an interface so we can't really tell anything...}return !OBJECT_EQUALS.equals(equals);}public static boolean overridesHashCode(Class clazz) {Method hashCode;try {hashCode = clazz.getMethod("hashCode", NO_PARAM);}catch (NoSuchMethodException nsme) {return false; //its an interface so we can't really tell anything...}return !OBJECT_HASHCODE.equals(hashCode);}public static Class classForName(String name) throws ClassNotFoundException {try {ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();if ( contextClassLoader != null ) {return contextClassLoader.loadClass(name);}}catch ( Throwable t ) {}return Class.forName( name );}public static Class classForName(String name, Class caller) throws ClassNotFoundException {try {ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();if ( contextClassLoader != null ) {return contextClassLoader.loadClass( name );}}catch ( Throwable e ) {}//使用给定的类加载器，返回与带有给定字符串名的类或接口相关联的 Class 对象。return Class.forName( name, true, caller.getClassLoader() );}//getModifiers()作为整数返回由此 Member 所表示的成员或构造方法的 Java 语言修饰符。//isPublic() 如果整数参数包括 public 修饰符，则返回 true，否则返回 false。public static boolean isPublic(Class clazz, Member member) {return Modifier.isPublic( member.getModifiers() ) && Modifier.isPublic( clazz.getModifiers() );}public static Constructor getDefaultConstructor(Class clazz) throws PropertyNotFoundException {if ( isAbstractClass(clazz) ) return null;try {Constructor constructor = clazz.getDeclaredConstructor(NO_CLASSES);if ( !isPublic(clazz, constructor) ) {constructor.setAccessible(true);}return constructor;}catch (NoSuchMethodException nme) {throw new PropertyNotFoundException("Object class " + clazz.getName() +" must declare a default (no-argument) constructor");}}public static boolean isAbstractClass(Class clazz) {int modifier = clazz.getModifiers();return Modifier.isAbstract(modifier) || Modifier.isInterface(modifier);}public static boolean isFinalClass(Class clazz) {return Modifier.isFinal( clazz.getModifiers() );}public static Constructor getConstructor(Class clazz, Type[] types) throws PropertyNotFoundException {final Constructor[] candidates = clazz.getConstructors();for ( int i=0; i<candidates.length; i++ ) {final Constructor constructor = candidates[i];final Class[] params = constructor.getParameterTypes();if ( params.length==types.length ) {boolean found = true;for ( int j=0; j<params.length; j++ ) {//isAssignableFrom(Class<?> cls) //判定此 Class 对象所表示的类或接口与指定的 Class 参数所表示的类或接口是否相同，或是否是其超类或超接口。final boolean ok = params[j].isAssignableFrom( types[j].getReturnedClass() ) || (//TODO 没看懂types[j] instanceof PrimitiveType &&params[j] == ( (PrimitiveType) types[j] ).getPrimitiveClass());if (!ok) {found = false;break;}}if (found) {if ( !isPublic(clazz, constructor) ) constructor.setAccessible(true);return constructor;}}}throw new PropertyNotFoundException( "no appropriate constructor in class: " + clazz.getName() );}public static Method getMethod(Class clazz, Method method) {try {return clazz.getMethod( method.getName(), method.getParameterTypes() );}catch (Exception e) {return null;}}}