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96 lines
2.4 KiB
96 lines
2.4 KiB
package mightypork.utils;
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import java.lang.annotation.Annotation;
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import java.lang.reflect.Field;
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import java.lang.reflect.Modifier;
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import java.lang.reflect.ParameterizedType;
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import java.lang.reflect.Type;
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/**
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* Miscelanous reflection-related utilities
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*
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* @author Ondřej Hruška (MightyPork)
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*/
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public class Reflect {
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/**
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* Get annotation of given type from an object
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*
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* @param tested the examined object
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* @param annotation annotation we want
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* @return the anotation on that object, or null
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*/
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public static <T extends Annotation> T getAnnotation(Object tested, Class<T> annotation)
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{
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return tested.getClass().getAnnotation(annotation);
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}
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/**
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* Check if an object has an annotation of given trype
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*
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* @param tested the examined object
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* @param annotation annotation we want
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* @return true if the annotation is present on the object
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*/
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public static boolean hasAnnotation(Object tested, Class<? extends Annotation> annotation)
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{
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return tested.getClass().isAnnotationPresent(annotation);
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}
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/**
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* Get generic parameters of a class
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*
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* @param clazz the examined class
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* @return parameter types
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*/
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public static Class<?>[] getGenericParameters(Class<?> clazz)
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{
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// BEHOLD, MAGIC!
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final Type evtc = clazz.getGenericSuperclass();
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if (evtc instanceof ParameterizedType) {
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final Type[] types = ((ParameterizedType) evtc).getActualTypeArguments();
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final Class<?>[] classes = new Class<?>[types.length];
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for (int i = 0; i < types.length; i++) {
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classes[i] = (Class<?>) types[i];
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}
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return classes;
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}
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throw new RuntimeException(Str.val(clazz) + " is not generic.");
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}
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/**
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* Get value of a public static final field. If the modifiers don't match,
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* an exception is thrown.
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*
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* @param objClass the class
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* @param fieldName field to retrieve
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* @return the field value
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* @throws ReflectiveOperationException if the field is not constant, or if
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* the value could not be retrieved.
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*/
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public static Object getConstantFieldValue(Class<?> objClass, String fieldName) throws ReflectiveOperationException
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{
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final Field fld = objClass.getDeclaredField(fieldName);
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final int modif = fld.getModifiers();
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if (!Modifier.isFinal(modif) || !Modifier.isStatic(modif)) {
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throw new ReflectiveOperationException("The " + fieldName + " field of " + Str.val(objClass) + " must be static and final!");
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}
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fld.setAccessible(true);
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return fld.get(null);
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}
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}
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