/*
* Copyright (c) 2011-2017, Data Geekery GmbH (http://www.datageekery.com)
*
* 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 org.jooq.tools.reflect;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;
/**
* A wrapper for an {@link Object} or {@link Class} upon which reflective calls
* can be made.
* <p>
* An example of using <code>Reflect</code> is <code><pre>
* // Static import all reflection methods to decrease verbosity
* import static org.joor.Reflect.*;
*
* // Wrap an Object / Class / class name with the on() method:
* on("java.lang.String")
* // Invoke constructors using the create() method:
* .create("Hello World")
* // Invoke methods using the call() method:
* .call("toString")
* // Retrieve the wrapped object
*
* @author Lukas Eder
* @author Irek Matysiewicz
*/
public class Reflect {
// ---------------------------------------------------------------------
// Static API used as entrance points to the fluent API
// ---------------------------------------------------------------------
/**
* Wrap a class name.
* <p>
* This is the same as calling <code>on(Class.forName(name))</code>
*
* @param name A fully qualified class name
* @return A wrapped class object, to be used for further reflection.
* @throws ReflectException If any reflection exception occurred.
* @see #on(Class)
*/
public static Reflect on(String name) throws ReflectException {
return on(forName(name));
}
/**
* Wrap a class.
* <p>
* Use this when you want to access static fields and methods on a
* {@link Class} object, or as a basis for constructing objects of that
* class using {@link #create(Object...)}
*
* @param clazz The class to be wrapped
* @return A wrapped class object, to be used for further reflection.
*/
public static Reflect on(Class<?> clazz) {
return new Reflect(clazz);
}
/**
* Wrap an object.
* <p>
* Use this when you want to access instance fields and methods on any
* {@link Object}
*
* @param object The object to be wrapped
* @return A wrapped object, to be used for further reflection.
*/
public static Reflect on(Object object) {
return new Reflect(object);
}
/**
* Conveniently render an {@link AccessibleObject} accessible.
* <p>
* To prevent {@link SecurityException}, this is only done if the argument
* object and its declaring class are non-public.
*
* @param accessible The object to render accessible
* @return The argument object rendered accessible
*/
public static <T extends AccessibleObject> T accessible(T accessible) {
if (accessible == null) {
return null;
}
if (accessible instanceof Member) {
Member member = (Member) accessible;
if (Modifier.isPublic(member.getModifiers()) &&
Modifier.isPublic(member.getDeclaringClass().getModifiers())) {
return accessible;
}
}
// [jOOQ #3392] The accessible flag is set to false by default, also for public members.
if (!accessible.isAccessible()) {
accessible.setAccessible(true);
}
return accessible;
}
// ---------------------------------------------------------------------
// Members
// ---------------------------------------------------------------------
/**
* The wrapped object
*/
private final Object object;
/**
* A flag indicating whether the wrapped object is a {@link Class} (for
* accessing static fields and methods), or any other type of {@link Object}
* (for accessing instance fields and methods).
*/
private final boolean isClass;
// ---------------------------------------------------------------------
// Constructors
// ---------------------------------------------------------------------
private Reflect(Class<?> type) {
this.object = type;
this.isClass = true;
}
private Reflect(Object object) {
this.object = object;
this.isClass = false;
}
// ---------------------------------------------------------------------
// Fluent Reflection API
// ---------------------------------------------------------------------
/**
* Get the wrapped object
*
* @param <T> A convenience generic parameter for automatic unsafe casting
*/
@SuppressWarnings("unchecked")
public <T> T get() {
return (T) object;
}
/**
* Set a field value.
* <p>
* This is roughly equivalent to {@link Field#set(Object, Object)}. If the
* wrapped object is a {@link Class}, then this will set a value to a static
* member field. If the wrapped object is any other {@link Object}, then
* this will set a value to an instance member field.
*
* @param name The field name
* @param value The new field value
* @return The same wrapped object, to be used for further reflection.
* @throws ReflectException If any reflection exception occurred.
*/
public Reflect set(String name, Object value) throws ReflectException {
try {
Field field = field0(name);
field.set(object, unwrap(value));
return this;
}
catch (Exception e) {
throw new ReflectException(e);
}
}
/**
* Get a field value.
* <p>
* This is roughly equivalent to {@link Field#get(Object)}. If the wrapped
* object is a {@link Class}, then this will get a value from a static
* member field. If the wrapped object is any other {@link Object}, then
* this will get a value from an instance member field.
* <p>
* If you want to "navigate" to a wrapped version of the field, use
* {@link #field(String)} instead.
*
* @param name The field name
* @return The field value
* @throws ReflectException If any reflection exception occurred.
* @see #field(String)
*/
public <T> T get(String name) throws ReflectException {
return field(name).<T>get();
}
/**
* Get a wrapped field.
* <p>
* This is roughly equivalent to {@link Field#get(Object)}. If the wrapped
* object is a {@link Class}, then this will wrap a static member field. If
* the wrapped object is any other {@link Object}, then this wrap an
* instance member field.
*
* @param name The field name
* @return The wrapped field
* @throws ReflectException If any reflection exception occurred.
*/
public Reflect field(String name) throws ReflectException {
try {
Field field = field0(name);
return on(field.get(object));
}
catch (Exception e) {
throw new ReflectException(e);
}
}
private Field field0(String name) throws ReflectException {
Class<?> type = type();
// Try getting a public field
try {
return type.getField(name);
}
// Try again, getting a non-public field
catch (NoSuchFieldException e) {
do {
try {
return accessible(type.getDeclaredField(name));
}
catch (NoSuchFieldException ignore) {}
type = type.getSuperclass();
}
while (type != null);
throw new ReflectException(e);
}
}
/**
* Get a Map containing field names and wrapped values for the fields'
* values.
* <p>
* If the wrapped object is a {@link Class}, then this will return static
* fields. If the wrapped object is any other {@link Object}, then this will
* return instance fields.
* <p>
* These two calls are equivalent <code><pre>
* on(object).field("myField");
* on(object).fields().get("myField");
* </pre></code>
*
* @return A map containing field names and wrapped values.
*/
public Map<String, Reflect> fields() {
Map<String, Reflect> result = new LinkedHashMap<String, Reflect>();
Class<?> type = type();
do {
for (Field field : type.getDeclaredFields()) {
if (!isClass ^ Modifier.isStatic(field.getModifiers())) {
String name = field.getName();
if (!result.containsKey(name))
result.put(name, field(name));
}
}
type = type.getSuperclass();
}
while (type != null);
return result;
}
/**
* Call a method by its name.
* <p>
* This is a convenience method for calling
* <code>call(name, new Object[0])</code>
*
* @param name The method name
* @return The wrapped method result or the same wrapped object if the
* method returns <code>void</code>, to be used for further
* reflection.
* @throws ReflectException If any reflection exception occurred.
* @see #call(String, Object...)
*/
public Reflect call(String name) throws ReflectException {
return call(name, new Object[0]);
}
/**
* Call a method by its name.
* <p>
* This is roughly equivalent to {@link Method#invoke(Object, Object...)}.
* If the wrapped object is a {@link Class}, then this will invoke a static
* method. If the wrapped object is any other {@link Object}, then this will
* invoke an instance method.
* <p>
* Just like {@link Method#invoke(Object, Object...)}, this will try to wrap
* primitive types or unwrap primitive type wrappers if applicable. If
* several methods are applicable, by that rule, the first one encountered
* is called. i.e. when calling <code><pre>
* on(...).call("method", 1, 1);
* </pre></code> The first of the following methods will be called:
* <code><pre>
* public void method(int param1, Integer param2);
* public void method(Integer param1, int param2);
* public void method(Number param1, Number param2);
* public void method(Number param1, Object param2);
* public void method(int param1, Object param2);
* </pre></code>
* <p>
* The best matching method is searched for with the following strategy:
* <ol>
* <li>public method with exact signature match in class hierarchy</li>
* <li>non-public method with exact signature match on declaring class</li>
* <li>public method with similar signature in class hierarchy</li>
* <li>non-public method with similar signature on declaring class</li>
* </ol>
*
* @param name The method name
* @param args The method arguments
* @return The wrapped method result or the same wrapped object if the
* method returns <code>void</code>, to be used for further
* reflection.
* @throws ReflectException If any reflection exception occurred.
*/
public Reflect call(String name, Object... args) throws ReflectException {
Class<?>[] types = types(args);
// Try invoking the "canonical" method, i.e. the one with exact
// matching argument types
try {
Method method = exactMethod(name, types);
return on(method, object, args);
}
// If there is no exact match, try to find a method that has a "similar"
// signature if primitive argument types are converted to their wrappers
catch (NoSuchMethodException e) {
try {
Method method = similarMethod(name, types);
return on(method, object, args);
} catch (NoSuchMethodException e1) {
throw new ReflectException(e1);
}
}
}
/**
* Searches a method with the exact same signature as desired.
* <p>
* If a public method is found in the class hierarchy, this method is returned.
* Otherwise a private method with the exact same signature is returned.
* If no exact match could be found, we let the {@code NoSuchMethodException} pass through.
*/
private Method exactMethod(String name, Class<?>[] types) throws NoSuchMethodException {
Class<?> type = type();
// first priority: find a public method with exact signature match in class hierarchy
try {
return type.getMethod(name, types);
}
// second priority: find a private method with exact signature match on declaring class
catch (NoSuchMethodException e) {
do {
try {
return type.getDeclaredMethod(name, types);
}
catch (NoSuchMethodException ignore) {}
type = type.getSuperclass();
}
while (type != null);
throw new NoSuchMethodException();
}
}
/**
* Searches a method with a similar signature as desired using
* {@link #isSimilarSignature(java.lang.reflect.Method, String, Class[])}.
* <p>
* First public methods are searched in the class hierarchy, then private
* methods on the declaring class. If a method could be found, it is
* returned, otherwise a {@code NoSuchMethodException} is thrown.
*/
private Method similarMethod(String name, Class<?>[] types) throws NoSuchMethodException {
Class<?> type = type();
// first priority: find a public method with a "similar" signature in class hierarchy
// similar interpreted in when primitive argument types are converted to their wrappers
for (Method method : type.getMethods()) {
if (isSimilarSignature(method, name, types)) {
return method;
}
}
// second priority: find a non-public method with a "similar" signature on declaring class
do {
for (Method method : type.getDeclaredMethods()) {
if (isSimilarSignature(method, name, types)) {
return method;
}
}
type = type.getSuperclass();
}
while (type != null);
throw new NoSuchMethodException("No similar method " + name + " with params " + Arrays.toString(types) + " could be found on type " + type() + ".");
}
/**
* Determines if a method has a "similar" signature, especially if wrapping
* primitive argument types would result in an exactly matching signature.
*/
private boolean isSimilarSignature(Method possiblyMatchingMethod, String desiredMethodName, Class<?>[] desiredParamTypes) {
return possiblyMatchingMethod.getName().equals(desiredMethodName) && match(possiblyMatchingMethod.getParameterTypes(), desiredParamTypes);
}
/**
* Call a constructor.
* <p>
* This is a convenience method for calling
* <code>create(new Object[0])</code>
*
* @return The wrapped new object, to be used for further reflection.
* @throws ReflectException If any reflection exception occurred.
* @see #create(Object...)
*/
public Reflect create() throws ReflectException {
return create(new Object[0]);
}
/**
* Call a constructor.
* <p>
* This is roughly equivalent to {@link Constructor#newInstance(Object...)}.
* If the wrapped object is a {@link Class}, then this will create a new
* object of that class. If the wrapped object is any other {@link Object},
* then this will create a new object of the same type.
* <p>
* Just like {@link Constructor#newInstance(Object...)}, this will try to
* wrap primitive types or unwrap primitive type wrappers if applicable. If
* several constructors are applicable, by that rule, the first one
* encountered is called. i.e. when calling <code><pre>
* on(C.class).create(1, 1);
* </pre></code> The first of the following constructors will be applied:
* <code><pre>
* public C(int param1, Integer param2);
* public C(Integer param1, int param2);
* public C(Number param1, Number param2);
* public C(Number param1, Object param2);
* public C(int param1, Object param2);
* </pre></code>
*
* @param args The constructor arguments
* @return The wrapped new object, to be used for further reflection.
* @throws ReflectException If any reflection exception occurred.
*/
public Reflect create(Object... args) throws ReflectException {
Class<?>[] types = types(args);
// Try invoking the "canonical" constructor, i.e. the one with exact
// matching argument types
try {
Constructor<?> constructor = type().getDeclaredConstructor(types);
return on(constructor, args);
}
// If there is no exact match, try to find one that has a "similar"
// signature if primitive argument types are converted to their wrappers
catch (NoSuchMethodException e) {
for (Constructor<?> constructor : type().getDeclaredConstructors()) {
if (match(constructor.getParameterTypes(), types)) {
return on(constructor, args);
}
}
throw new ReflectException(e);
}
}
/**
* Create a proxy for the wrapped object allowing to typesafely invoke
* methods on it using a custom interface
*
* @param proxyType The interface type that is implemented by the proxy
* @return A proxy for the wrapped object
*/
@SuppressWarnings("unchecked")
public <P> P as(Class<P> proxyType) {
final boolean isMap = (object instanceof Map);
final InvocationHandler handler = new InvocationHandler() {
@SuppressWarnings("null")
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String name = method.getName();
// Actual method name matches always come first
try {
return on(object).call(name, args).get();
}
// [#14] Emulate POJO behaviour on wrapped map objects
catch (ReflectException e) {
if (isMap) {
Map<String, Object> map = (Map<String, Object>) object;
int length = (args == null ? 0 : args.length);
if (length == 0 && name.startsWith("get")) {
return map.get(property(name.substring(3)));
}
else if (length == 0 && name.startsWith("is")) {
return map.get(property(name.substring(2)));
}
else if (length == 1 && name.startsWith("set")) {
map.put(property(name.substring(3)), args[0]);
return null;
}
}
throw e;
}
}
};
return (P) Proxy.newProxyInstance(proxyType.getClassLoader(), new Class[] { proxyType }, handler);
}
/**
* Get the POJO property name of an getter/setter
*/
private static String property(String string) {
int length = string.length();
if (length == 0) {
return "";
}
else if (length == 1) {
return string.toLowerCase();
}
else {
return string.substring(0, 1).toLowerCase() + string.substring(1);
}
}
// ---------------------------------------------------------------------
// Object API
// ---------------------------------------------------------------------
/**
* Check whether two arrays of types match, converting primitive types to
* their corresponding wrappers.
*/
private boolean match(Class<?>[] declaredTypes, Class<?>[] actualTypes) {
if (declaredTypes.length == actualTypes.length) {
for (int i = 0; i < actualTypes.length; i++) {
if (actualTypes[i] == NULL.class)
continue;
if (wrapper(declaredTypes[i]).isAssignableFrom(wrapper(actualTypes[i])))
continue;
return false;
}
return true;
}
else {
return false;
}
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
return object.hashCode();
}
/**
* {@inheritDoc}
*/
@Override
public boolean equals(Object obj) {
if (obj instanceof Reflect) {
return object.equals(((Reflect) obj).get());
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return object.toString();
}
// ---------------------------------------------------------------------
// Utility methods
// ---------------------------------------------------------------------
/**
* Wrap an object created from a constructor
*/
private static Reflect on(Constructor<?> constructor, Object... args) throws ReflectException {
try {
return on(accessible(constructor).newInstance(args));
}
catch (Exception e) {
throw new ReflectException(e);
}
}
/**
* Wrap an object returned from a method
*/
private static Reflect on(Method method, Object object, Object... args) throws ReflectException {
try {
accessible(method);
if (method.getReturnType() == void.class) {
method.invoke(object, args);
return on(object);
}
else {
return on(method.invoke(object, args));
}
}
catch (Exception e) {
throw new ReflectException(e);
}
}
/**
* Unwrap an object
*/
private static Object unwrap(Object object) {
if (object instanceof Reflect) {
return ((Reflect) object).get();
}
return object;
}
/**
* Get an array of types for an array of objects
*
* @see Object#getClass()
*/
private static Class<?>[] types(Object... values) {
if (values == null) {
return new Class[0];
}
Class<?>[] result = new Class[values.length];
for (int i = 0; i < values.length; i++) {
Object value = values[i];
result[i] = value == null ? NULL.class : value.getClass();
}
return result;
}
/**
* Load a class
*
* @see Class#forName(String)
*/
private static Class<?> forName(String name) throws ReflectException {
try {
return Class.forName(name);
}
catch (Exception e) {
throw new ReflectException(e);
}
}
/**
* Get the type of the wrapped object.
*
* @see Object#getClass()
*/
public Class<?> type() {
if (isClass) {
return (Class<?>) object;
}
else {
return object.getClass();
}
}
/**
* Get a wrapper type for a primitive type, or the argument type itself, if
* it is not a primitive type.
*/
public static Class<?> wrapper(Class<?> type) {
if (type == null) {
return null;
}
else if (type.isPrimitive()) {
if (boolean.class == type) {
return Boolean.class;
}
else if (int.class == type) {
return Integer.class;
}
else if (long.class == type) {
return Long.class;
}
else if (short.class == type) {
return Short.class;
}
else if (byte.class == type) {
return Byte.class;
}
else if (double.class == type) {
return Double.class;
}
else if (float.class == type) {
return Float.class;
}
else if (char.class == type) {
return Character.class;
}
else if (void.class == type) {
return Void.class;
}
}
return type;
}
private static class NULL {}
}