一个小巧方便的java反射工具

对lukas eder写的reflect做了一些扩展, 使其更强大, 满足自己的使用场景.

/**
 * Copyright (c) 2011-2012, Lukas Eder, lukas.eder@gmail.com
 * All rights reserved.
 *
 * This software is licensed to you under the Apache License, Version 2.0
 * (the "License"); You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * . Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * . Neither the name "jOOR" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.*;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 *
 * 为了满足自己的需求, 支持对私有属性和方法进行反射, 包括一直向上父类查找方法或属性, 因为完全暴露了方法和属性, 谨慎使用
 *
 * 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
 */
public class Reflect {
	private final static Logger logger = LoggerFactory.getLogger(Reflect.class);

	public static class Param<T>{
		Class<?> type;
		T value;
		public Param(String name, T value) {
			Class<?> type = null;
			try {
				type = Class.forName(name);
			} catch (ClassNotFoundException e) {
				throw new RuntimeException("class name:" + name, e);
			}
			this.type = type;
			this.value = value;
		}

		public Param(Class<?> type, T value) {
			super();
			this.type = type;
			this.value = value;
		}
		public Param<T> type(Class<?> type){
			this.type = type;
			return this;
		}
		public Param<T> value(T value){
			this.value = value;
			return this;
		}
	}


	// ---------------------------------------------------------------------
	// 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.
	 * 
	 * @see #on(Class)
	 */
	public static Reflect on(String name)  {
		return on(forName(name));
	}

	/**根据类名称构造实例*/
	public static Reflect instance(String name)  {
		Object o;
		try {
			o = forName(name).newInstance();
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
		return on(o);
	}

	/**
	 * 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 java.lang.reflect.AccessibleObject} accessible
	 *
	 * @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.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 <T> Reflect(T 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 java.lang.reflect.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.
	 * 
	 */
	public Reflect set(String name, final Object value) {
		return doExecute(name, new Executor() {
			@Override
			public Reflect execute(Field field)throws Exception {
				field.set(object, unwrap(value));
				return on(object);
			}});
	}

	/**
	 * Get a field value.
	 * <p>
	 * This is roughly equivalent to {@link java.lang.reflect.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
	 * 
	 * @see #field(String)
	 */
	public <T> T get(String name) {
		return field(name).<T>get();
	}

	interface Executor{
		Reflect execute(Field field)throws Exception;
	}

	/**
	 * Get a wrapped field.
	 * <p>
	 * This is roughly equivalent to {@link java.lang.reflect.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
	 * 
	 */
	public Reflect field(String name) {
		return doExecute(name, new Executor() {
			@Override
			public Reflect execute(Field field)throws Exception {
				return on(field.get(object));
			}});
	}

	private Reflect doExecute(String name, Executor executor) {
		Class<?> useClazz = type();
		Field field = null;
		do {
			try {
				field = useClazz.getDeclaredField(name);
				field = accessible(field);
				return executor.execute(field);
			} catch (NoSuchFieldException e) {
				//
			} catch (Exception e) {
				throw new RuntimeException("class:" + useClazz + ", name:" + name, e);
			}
			if (field == null) {
				useClazz = useClazz.getSuperclass();
			}
		} while (useClazz != null);

		throw new RuntimeException("don't execute on field[" + name + "]");
	}

	/**
	 * 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>();

		for (Field field : type().getFields()) {
			if (!isClass ^ Modifier.isStatic(field.getModifiers())) {
				String name = field.getName();
				result.put(name, field(name));
			}
		}

		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.
	 * 
	 * @see #call(String, Object...)
	 */
	public Reflect call(String name) {
		return call(name, new Object[0]);
	}

	/**
	 * Call a method by its name.
	 * <p>
	 * This is roughly equivalent to {@link java.lang.reflect.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 java.lang.reflect.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>
	 *
	 * @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.
	 * 
	 */
	public Reflect call(String name, Object... args) {
		//return doCall(name, types(args), args);
		Class<?>[] types;
		Object[] values = null;
		if (args == null) {
			types = new Class[0];
		}else {
			types = new Class[args.length];

			for (int i = 0; i < args.length; i++) {
				Object arg = args[i];
				types[i] = (arg instanceof Param) ? ((Param)arg).type : arg.getClass();
			}

			values = new Object[args.length];
			for (int i = 0; i < args.length; i++) {
				Object arg = args[i];
				values[i] = (arg instanceof Param) ? ((Param)arg).value : arg;
			}
		}

		return doCall(name, types, values);
	}

	public static <T> Param<T> param(Class<?> type, T value) {
		return new Param<T>(type, value);
	}

	private Reflect doCall(String name, Class<?>[] types, Object[] values) {
		Class<?> clazz = type();
		Method method = null;
		do {
			try {
				method = clazz.getDeclaredMethod(name, types);
				return on(method, object, values);
			} catch (NoSuchMethodException e) {
				logger.warn("class:" + clazz.getName() + ", mehtod:" + name + "(" + Arrays.toString(types) + ")", e);
			} catch (Exception e) {
				throw new RuntimeException("class:" + clazz.getName() + ", method:" + name + "(" + Arrays.toString(types) + ")", e);
			}
			if (method == null) {
				clazz = clazz.getSuperclass();
			}
		} while (clazz != null);

		throw new RuntimeException("don't execute the method " + type() + "." + name + "(" + Arrays.toString(values) + ")");
	}

	/**
	 * 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.
	 * 
	 * @see #create(Object...)
	 */
	public Reflect create() {
		return create(new Object[0]);
	}

	/**
	 * Call a constructor.
	 * <p>
	 * This is roughly equivalent to {@link java.lang.reflect.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 java.lang.reflect.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.
	 * 
	 */
	public Reflect create(Object... args) {
		Class<?>[] types = types(args);

		return doCreate(types, args);
	}

	public Reflect create(Param<?>... args) {
		Class<?>[] types = null;
		Object[] values = null;
		if (args == null) {
			types = new Class[0];
		}else {
			types = new Class[args.length];

			for (int i = 0; i < args.length; i++) {
				types[i] = args[i].type;
			}

			values = new Object[args.length];
			for (int i = 0; i < args.length; i++) {
				values[i] = args[i].value;
			}
		}

		return doCreate(types, values);
	}

	private Reflect doCreate(Class<?>[] types, Object... args) {
		// Try invoking the "canonical" constructor, i.e. the one with exact
		// matching argument types
		try {
			Constructor<?> constructor = type().getConstructor(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 RuntimeException(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 InvocationHandler handler = new InvocationHandler() {
			@Override
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
				return on(object).call(method.getName(), args).get();
			}
		};

		return (P) Proxy.newProxyInstance(proxyType.getClassLoader(), new Class[] { proxyType }, handler);
	}

	// ---------------------------------------------------------------------
	// 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 (!wrapper(declaredTypes[i]).isAssignableFrom(wrapper(actualTypes[i]))) {
					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) {
		try {
			constructor = accessible(constructor);
			return on(constructor.newInstance(args));
		}
		catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	/**
	 * Wrap an object returned from a method
	 */
	private static Reflect on(Method method, Object object, Object... args) {
		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 RuntimeException(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++) {
			result[i] = values[i].getClass();
		}

		return result;
	}

	/**
	 * Load a class
	 *
	 * @see Class#forName(String)
	 */
	private static Class<?> forName(String name) {
		try {
			return Class.forName(name);
		}
		catch (Exception e) {
			throw new RuntimeException(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.
	 */
	private static Class<?> wrapper(Class<?> type) {
		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 {
			return type;
		}
	}

}