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//$Id: Reflections.java 9572 2008-11-15 22:33:10Z shane.bryzak@jboss.com $package org.jboss.seam.util;import java.beans.Introspector;import java.lang.annotation.Annotation;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Member;import java.lang.reflect.Method;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;import java.util.ArrayList;import java.util.List;public class Reflections{ public static Object invoke(Method method, Object target, Object... args) throws Exception { try { return method.invoke( target, args ); } catch (IllegalArgumentException iae) { String message = "Could not invoke method by reflection: " + toString(method); if (args!=null && args.length>0) { message += " with parameters: (" + Strings.toClassNameString(", ", args) + ')'; } message += " on: " + target.getClass().getName(); throw new IllegalArgumentException(message, iae); } catch (InvocationTargetException ite) { if ( ite.getCause() instanceof Exception ) { throw (Exception) ite.getCause(); } else { throw ite; } } } public static Object get(Field field, Object target) throws Exception { boolean accessible = field.isAccessible(); try { field.setAccessible(true); return field.get(target); } catch (IllegalArgumentException iae) { String message = "Could not get field value by reflection: " + toString(field) + " on: " + target.getClass().getName(); throw new IllegalArgumentException(message, iae); } finally { field.setAccessible(accessible); } } public static void set(Field field, Object target, Object value) throws Exception { try { field.set(target, value); } catch (IllegalArgumentException iae) { // target may be null if field is static so use field.getDeclaringClass() instead String message = "Could not set field value by reflection: " + toString(field) + " on: " + field.getDeclaringClass().getName(); if (value==null) { message += " with null value"; } else { message += " with value: " + value.getClass(); } throw new IllegalArgumentException(message, iae); } } public static Object getAndWrap(Field field, Object target) { boolean accessible = field.isAccessible(); try { field.setAccessible(true); return get(field, target); } catch (Exception e) { if (e instanceof RuntimeException) { throw (RuntimeException) e; } else { throw new IllegalArgumentException("exception setting: " + field.getName(), e); } } finally { field.setAccessible(accessible); } } public static void setAndWrap(Field field, Object target, Object value) { boolean accessible = field.isAccessible(); try { field.setAccessible(true); set(field, target, value); } catch (Exception e) { if (e instanceof RuntimeException) { throw (RuntimeException) e; } else { throw new IllegalArgumentException("exception setting: " + field.getName(), e); } } finally { field.setAccessible(accessible); } } public static Object invokeAndWrap(Method method, Object target, Object... args) { try { return invoke(method, target, args); } catch (Exception e) { if (e instanceof RuntimeException) { throw (RuntimeException) e; } else { throw new RuntimeException("exception invoking: " + method.getName(), e); } } } public static String toString(Method method) { return Strings.unqualify( method.getDeclaringClass().getName() ) + '.' + method.getName() + '(' + Strings.toString( ", ", method.getParameterTypes() ) + ')'; } public static String toString(Member member) { return Strings.unqualify( member.getDeclaringClass().getName() ) + '.' + member.getName(); } public static Class classForName(String name) throws ClassNotFoundException { try { return Thread.currentThread().getContextClassLoader().loadClass(name); } catch (Exception e) { return Class.forName(name); } } /** * Return's true if the class can be loaded using Reflections.classForName() */ public static boolean isClassAvailable(String name) { try { classForName(name); } catch (ClassNotFoundException e) { return false; } return true; } public static Class getCollectionElementType(Type collectionType) { if ( !(collectionType instanceof ParameterizedType) ) { throw new IllegalArgumentException("collection type not parameterized"); } Type[] typeArguments = ( (ParameterizedType) collectionType ).getActualTypeArguments(); if (typeArguments.length==0) { throw new IllegalArgumentException("no type arguments for collection type"); } Type typeArgument = typeArguments.length==1 ? typeArguments : typeArguments; //handle Maps if (typeArgument instanceof ParameterizedType) { typeArgument = ((ParameterizedType) typeArgument).getRawType(); } if ( !(typeArgument instanceof Class) ) { throw new IllegalArgumentException("type argument not a class"); } return (Class) typeArgument; } public static Class getMapKeyType(Type collectionType) { if ( !(collectionType instanceof ParameterizedType) ) { throw new IllegalArgumentException("collection type not parameterized"); } Type[] typeArguments = ( (ParameterizedType) collectionType ).getActualTypeArguments(); if (typeArguments.length==0) { throw new IllegalArgumentException("no type arguments for collection type"); } Type typeArgument = typeArguments; if ( !(typeArgument instanceof Class) ) { throw new IllegalArgumentException("type argument not a class"); } return (Class) typeArgument; } public static Method getSetterMethod(Class clazz, String name) { Method[] methods = clazz.getMethods(); for (Method method: methods) { String methodName = method.getName(); if ( methodName.startsWith("set") && method.getParameterTypes().length==1 ) { if ( Introspector.decapitalize( methodName.substring(3) ).equals(name) ) { return method; } } } throw new IllegalArgumentException("no such setter method: " + clazz.getName() + '.' + name); } public static Method getGetterMethod(Class clazz, String name) { Method[] methods = clazz.getMethods(); for (Method method: methods) { String methodName = method.getName(); if ( method.getParameterTypes().length==0 ) { if ( methodName.startsWith("get") ) { if ( Introspector.decapitalize( methodName.substring(3) ).equals(name) ) { return method; } } else if ( methodName.startsWith("is") ) { if ( Introspector.decapitalize( methodName.substring(2) ).equals(name) ) { return method; } } } } throw new IllegalArgumentException("no such getter method: " + clazz.getName() + '.' + name); } /** * Get all the getter methods annotated with the given annotation. Returns an empty list if * none are found */ public static List<Method> getGetterMethods(Class clazz, Class annotation) { List<Method> methods = new ArrayList<Method>(); for (Method method : clazz.getMethods()) { if (method.isAnnotationPresent(annotation)) { methods.add(method); } } return methods; } public static Field getField(Class clazz, String name) { for ( Class superClass = clazz; superClass!=Object.class; superClass=superClass.getSuperclass() ) { try { return superClass.getDeclaredField(name); } catch (NoSuchFieldException nsfe) {} } throw new IllegalArgumentException("no such field: " + clazz.getName() + '.' + name); } /** * Get all the fields which are annotated with the given annotation. Returns an empty list * if none are found */ public static List<Field> getFields(Class clazz, Class annotation) { List<Field> fields = new ArrayList<Field>(); for (Class superClass = clazz; superClass!=Object.class; superClass=superClass.getSuperclass()) { for (Field field : superClass.getDeclaredFields()) { if (field.isAnnotationPresent(annotation)) { fields.add(field); } } } return fields; } public static Method getMethod(Annotation annotation, String name) { try { return annotation.annotationType().getMethod(name); } catch (NoSuchMethodException nsme) { return null; } } public static Method getMethod(Class clazz, String name) { for ( Class superClass = clazz; superClass!=Object.class; superClass=superClass.getSuperclass() ) { try { return superClass.getDeclaredMethod(name); } catch (NoSuchMethodException nsme) {} } throw new IllegalArgumentException("no such method: " + clazz.getName() + '.' + name); } /** * Check to see if clazz is an instance of name */ public static boolean isInstanceOf(Class clazz, String name) { if (name == null) { throw new IllegalArgumentException("name cannot be null"); } for (Class c = clazz; c != Object.class; c = c.getSuperclass()) { if (instanceOf(c, name)) { return true; } } return false; } private static boolean instanceOf(Class clazz, String name) { if (name.equals(clazz.getName())) { return true; } else { boolean found = false; Class[] interfaces = clazz.getInterfaces(); for (int i = 0; i < interfaces.length && !found; i++) { found = instanceOf(interfaces, name); } return found; } }}
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