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Google Cloud Dataflow Java SDK provides a simple, Java-based
interface for processing virtually any size data using Google cloud
resources. This artifact includes entire Dataflow Java SDK.
/*
* Copyright (C) 2015 Google Inc.
*
* Licensed 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 com.google.cloud.dataflow.sdk.util.common;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static java.util.Arrays.asList;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Queues;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Queue;
import javax.annotation.Nullable;
/**
* Utilities for working with with {@link Class Classes} and {@link Method Methods}.
*/
public class ReflectHelpers {
private static final Joiner COMMA_SEPARATOR = Joiner.on(", ");
/** A {@link Function} that turns a method into a simple method signature. */
public static final Function METHOD_FORMATTER = new Function() {
@Override
public String apply(Method input) {
String parameterTypes = FluentIterable.from(asList(input.getParameterTypes()))
.transform(CLASS_SIMPLE_NAME)
.join(COMMA_SEPARATOR);
return String.format("%s(%s)",
input.getName(),
parameterTypes);
}
};
/** A {@link Function} that turns a method into the declaring class + method signature. */
public static final Function CLASS_AND_METHOD_FORMATTER =
new Function() {
@Override
public String apply(Method input) {
return String.format("%s#%s",
CLASS_NAME.apply(input.getDeclaringClass()),
METHOD_FORMATTER.apply(input));
}
};
/** A {@link Function} with returns the classes name. */
public static final Function, String> CLASS_NAME =
new Function, String>() {
@Override
public String apply(Class input) {
return input.getName();
}
};
/** A {@link Function} with returns the classes name. */
public static final Function, String> CLASS_SIMPLE_NAME =
new Function, String>() {
@Override
public String apply(Class input) {
return input.getSimpleName();
}
};
/** A {@link Function} that formats types. */
public static final Function TYPE_SIMPLE_DESCRIPTION =
new Function() {
@Override
@Nullable
public String apply(@Nullable Type input) {
StringBuilder builder = new StringBuilder();
format(builder, input);
return builder.toString();
}
private void format(StringBuilder builder, Type t) {
if (t instanceof Class) {
formatClass(builder, (Class) t);
} else if (t instanceof TypeVariable) {
formatTypeVariable(builder, (TypeVariable) t);
} else if (t instanceof WildcardType) {
formatWildcardType(builder, (WildcardType) t);
} else if (t instanceof ParameterizedType) {
formatParameterizedType(builder, (ParameterizedType) t);
} else if (t instanceof GenericArrayType) {
formatGenericArrayType(builder, (GenericArrayType) t);
} else {
builder.append(t.toString());
}
}
private void formatClass(StringBuilder builder, Class clazz) {
builder.append(clazz.getSimpleName());
}
private void formatTypeVariable(StringBuilder builder, TypeVariable t) {
builder.append(t.getName());
}
private void formatWildcardType(StringBuilder builder, WildcardType t) {
builder.append("?");
for (Type lowerBound : t.getLowerBounds()) {
builder.append(" super ");
format(builder, lowerBound);
}
for (Type upperBound : t.getUpperBounds()) {
if (!Object.class.equals(upperBound)) {
builder.append(" extends ");
format(builder, upperBound);
}
}
}
private void formatParameterizedType(StringBuilder builder, ParameterizedType t) {
format(builder, t.getRawType());
builder.append('<');
COMMA_SEPARATOR.appendTo(builder,
FluentIterable.from(asList(t.getActualTypeArguments()))
.transform(TYPE_SIMPLE_DESCRIPTION));
builder.append('>');
}
private void formatGenericArrayType(StringBuilder builder, GenericArrayType t) {
format(builder, t.getGenericComponentType());
builder.append("[]");
}
};
/**
* Returns all interfaces of the given clazz.
* @param clazz
* @return
*/
public static FluentIterable> getClosureOfInterfaces(Class clazz) {
checkNotNull(clazz);
Queue> interfacesToProcess = Queues.newArrayDeque();
Collections.addAll(interfacesToProcess, clazz.getInterfaces());
LinkedHashSet> interfaces = new LinkedHashSet<>();
while (!interfacesToProcess.isEmpty()) {
Class current = interfacesToProcess.remove();
if (interfaces.add(current)) {
Collections.addAll(interfacesToProcess, current.getInterfaces());
}
}
return FluentIterable.from(interfaces);
}
/**
* Returns all the methods visible from the provided interfaces.
*
* @param interfaces The interfaces to use when searching for all their methods.
* @return An iterable of {@link Method}s which interfaces expose.
*/
public static Iterable getClosureOfMethodsOnInterfaces(
Iterable> interfaces) {
return FluentIterable.from(interfaces).transformAndConcat(
new Function, Iterable>() {
@Override
public Iterable apply(Class input) {
return getClosureOfMethodsOnInterface(input);
}
});
}
/**
* Returns all the methods visible from {@code iface}.
*
* @param iface The interface to use when searching for all its methods.
* @return An iterable of {@link Method}s which {@code iface} exposes.
*/
public static Iterable getClosureOfMethodsOnInterface(Class iface) {
checkNotNull(iface);
checkArgument(iface.isInterface());
ImmutableSet.Builder builder = ImmutableSet.builder();
Queue> interfacesToProcess = Queues.newArrayDeque();
interfacesToProcess.add(iface);
while (!interfacesToProcess.isEmpty()) {
Class current = interfacesToProcess.remove();
builder.add(current.getMethods());
interfacesToProcess.addAll(Arrays.asList(current.getInterfaces()));
}
return builder.build();
}
}