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Posted to commits@logging.apache.org by ma...@apache.org on 2014/09/14 07:01:23 UTC
[05/15] git commit: Add ReflectionUtil class for reflection
operations.
Add ReflectionUtil class for reflection operations.
- Even though every AccessibleObject is also a Member, this is not reflected in the JDK; thus, generics need to be used.
- Inspired by Spring: https://github.com/spring-projects/spring-framework/blob/master/spring-core/src/main/java/org/springframework/util/ReflectionUtils.java
Project: http://git-wip-us.apache.org/repos/asf/logging-log4j2/repo
Commit: http://git-wip-us.apache.org/repos/asf/logging-log4j2/commit/2f4a72cb
Tree: http://git-wip-us.apache.org/repos/asf/logging-log4j2/tree/2f4a72cb
Diff: http://git-wip-us.apache.org/repos/asf/logging-log4j2/diff/2f4a72cb
Branch: refs/heads/master
Commit: 2f4a72cbd1eb706e63244fe5af8bef69ce60568f
Parents: 5b36078
Author: Matt Sicker <ma...@apache.org>
Authored: Sat Sep 13 18:23:44 2014 -0500
Committer: Matt Sicker <ma...@apache.org>
Committed: Sat Sep 13 18:23:44 2014 -0500
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.../logging/log4j/core/util/ReflectionUtil.java | 141 +++++++++++++++++++
1 file changed, 141 insertions(+)
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http://git-wip-us.apache.org/repos/asf/logging-log4j2/blob/2f4a72cb/log4j-core/src/main/java/org/apache/logging/log4j/core/util/ReflectionUtil.java
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diff --git a/log4j-core/src/main/java/org/apache/logging/log4j/core/util/ReflectionUtil.java b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/ReflectionUtil.java
new file mode 100644
index 0000000..bdd913a
--- /dev/null
+++ b/log4j-core/src/main/java/org/apache/logging/log4j/core/util/ReflectionUtil.java
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache license, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the license for the specific language governing permissions and
+ * limitations under the license.
+ */
+
+package org.apache.logging.log4j.core.util;
+
+import java.lang.reflect.AccessibleObject;
+import java.lang.reflect.Field;
+import java.lang.reflect.Member;
+import java.lang.reflect.Modifier;
+
+/**
+ * Utility class for performing common reflective operations.
+ *
+ * @since 2.1
+ */
+public final class ReflectionUtil {
+ private ReflectionUtil() {
+ }
+
+ /**
+ * Indicates whether or not a {@link Member} is both public and is contained in a public class.
+ *
+ * @param member the Member to check for public accessibility (must not be {@code null}).
+ * @return {@code true} if {@code member} is public and contained in a public class.
+ * @throws NullPointerException if {@code member} is {@code null}.
+ */
+ public static <T extends AccessibleObject & Member> boolean isAccessible(final T member) {
+ Assert.requireNonNull(member, "No member provided");
+ return Modifier.isPublic(member.getModifiers()) && Modifier.isPublic(member.getDeclaringClass().getModifiers());
+ }
+
+ /**
+ * Makes a {@link Member} {@link AccessibleObject#isAccessible() accessible} if the member is not public.
+ *
+ * @param member the Member to make accessible (must not be {@code null}).
+ * @throws NullPointerException if {@code member} is {@code null}.
+ */
+ public static <T extends AccessibleObject & Member> void makeAccessible(final T member) {
+ if (!isAccessible(member) && !member.isAccessible()) {
+ member.setAccessible(true);
+ }
+ }
+
+ /**
+ * Makes a {@link Field} {@link AccessibleObject#isAccessible() accessible} if it is not public or if it is final.
+ *
+ * <p>Note that using this method to make a {@code final} field writable will most likely not work very well due to
+ * compiler optimizations and the like.</p>
+ *
+ * @param field the Field to make accessible (must not be {@code null}).
+ * @throws NullPointerException if {@code field} is {@code null}.
+ */
+ public static void makeAccessible(final Field field) {
+ Assert.requireNonNull(field, "No field provided");
+ if ((!isAccessible(field) || Modifier.isFinal(field.getModifiers())) && !field.isAccessible()) {
+ field.setAccessible(true);
+ }
+ }
+
+ /**
+ * Gets the value of a {@link Field}, making it accessible if required.
+ *
+ * @param field the Field to obtain a value from (must not be {@code null}).
+ * @param instance the instance to obtain the field value from or {@code null} only if the field is static.
+ * @return the value stored by the field.
+ * @throws NullPointerException if {@code field} is {@code null}, or if {@code instance} is {@code null} but
+ * {@code field} is not {@code static}.
+ * @see Field#get(Object)
+ */
+ public static Object getFieldValue(final Field field, final Object instance) {
+ makeAccessible(field);
+ if (!Modifier.isStatic(field.getModifiers())) {
+ Assert.requireNonNull(instance, "No instance given for non-static field");
+ }
+ try {
+ return field.get(instance);
+ } catch (final IllegalAccessException e) {
+ throw new UnsupportedOperationException(e);
+ }
+ }
+
+ /**
+ * Gets the value of a static {@link Field}, making it accessible if required.
+ *
+ * @param field the Field to obtain a value from (must not be {@code null}).
+ * @return the value stored by the static field.
+ * @throws NullPointerException if {@code field} is {@code null}, or if {@code field} is not {@code static}.
+ * @see Field#get(Object)
+ */
+ public static Object getStaticFieldValue(final Field field) {
+ return getFieldValue(field, null);
+ }
+
+ /**
+ * Sets the value of a {@link Field}, making it accessible if required.
+ *
+ * @param field the Field to write a value to (must not be {@code null}).
+ * @param instance the instance to write the value to or {@code null} only if the field is static.
+ * @param value the (possibly wrapped) value to write to the field.
+ * @throws NullPointerException if {@code field} is {@code null}, or if {@code instance} is {@code null} but
+ * {@code field} is not {@code static}.
+ * @see Field#set(Object, Object)
+ */
+ public static void setFieldValue(final Field field, final Object instance, final Object value) {
+ makeAccessible(field);
+ if (!Modifier.isStatic(field.getModifiers())) {
+ Assert.requireNonNull(instance, "No instance given for non-static field");
+ }
+ try {
+ field.set(instance, value);
+ } catch (final IllegalAccessException e) {
+ throw new UnsupportedOperationException(e);
+ }
+ }
+
+ /**
+ * Sets the value of a static {@link Field}, making it accessible if required.
+ *
+ * @param field the Field to write a value to (must not be {@code null}).
+ * @param value the (possibly wrapped) value to write to the field.
+ * @throws NullPointerException if {@code field} is {@code null}, or if {@code field} is not {@code static}.
+ * @see Field#set(Object, Object)
+ */
+ public static void setStaticFieldValue(final Field field, final Object value) {
+ setFieldValue(field, null, value);
+ }
+}