com.ttianjun.common.kit.ref.Reflect Maven / Gradle / Ivy
/**
* 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"
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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package com.ttianjun.common.kit.ref;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
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.
*
* An example of using Reflect is
* // 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 {
// ---------------------------------------------------------------------
// Static API used as entrance points to the fluent API
// ---------------------------------------------------------------------
/**
* Wrap a class name.
*
* This is the same as calling on(Class.forName(name))
*
* @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.
*
* 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.
*
* 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
*
* @param accessible
* The object to render accessible
* @return The argument object rendered accessible
*/
public static 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 Reflect(Object object) {
this.object = object;
this.isClass = false;
}
// ---------------------------------------------------------------------
// Fluent Reflection API
// ---------------------------------------------------------------------
/**
* Get the wrapped object
*
* @param
* A convenience generic parameter for automatic unsafe casting
*/
@SuppressWarnings("unchecked")
public T get() {
return (T) object;
}
/**
* Set a field value.
*
* 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 {
// Try setting a public field
Field field = type().getField(name);
field.set(object, unwrap(value));
return this;
} catch (Exception e1) {
// Try again, setting a non-public field
try {
accessible(type().getDeclaredField(name)).set(object, unwrap(value));
return this;
} catch (Exception e2) {
throw new ReflectException(e2);
}
}
}
/**
* Get a field value.
*
* 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.
*
* 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 get(String name) throws ReflectException {
return field(name). get();
}
/**
*
* TODO:(简单描述方法作用).
*
* @author kid create 2013-8-29
* @param clazz
* @param name
* @return
* @throws NoSuchFieldException
*/
public Field getDeclaredField(Class clazz, String name) throws NoSuchFieldException {
Field field = null;
while (clazz != Object.class) {
try {
field = clazz.getDeclaredField(name);
if (field != null)
break;
} catch (Exception e) {
clazz = clazz.getSuperclass();
}
}
if (field == null) {
throw new NoSuchFieldException("name is not found");
}
return field;
}
/**
* Get a wrapped field.
*
* 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 {
// Try getting a public field
Field field = type().getField(name);
return on(field.get(object));
} catch (Exception e1) {
// Try again, getting a non-public field
try {
return on(accessible(getDeclaredField(type(), name)).get(object));
} catch (Exception e2) {
throw new ReflectException(e2);
}
}
}
/**
* Get a Map containing field names and wrapped values for the fields' values.
*
* 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.
*
* These two calls are equivalent
* on(object).field("myField");
* on(object).fields().get("myField");
* fields() {
Map result = new LinkedHashMap();
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.
*
* This is a convenience method for calling call(name, new Object[0])
*
* @param name
* The method name
* @return The wrapped method result or the same wrapped object if the method returns void, 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.
*
* 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.
*
* 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
* on(...).call("method", 1, 1);
*
* 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);
*
* The best matching method is searched for with the following strategy:
*
* - public method with exact signature match in class hierarchy
* - non-public method with exact signature match on declaring class
* - public method with similar signature in class hierarchy
* - non-public method with similar signature on declaring class
*
*
* @param name
* The method name
* @param args
* The method arguments
* @return The wrapped method result or the same wrapped object if the method returns void, 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.
*
* 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 {
final 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) {
return type.getDeclaredMethod(name, types);
}
}
/**
* Searches a method with a similar signature as desired using
* {@link #isSimilarSignature(java.lang.reflect.Method, String, Class[])}.
*
* 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 {
final 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
for (Method method : type.getDeclaredMethods()) {
if (isSimilarSignature(method, name, types)) {
return method;
}
}
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.
*
* This is a convenience method for calling create(new Object[0])
*
* @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.
*
* 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.
*
* 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
* on(C.class).create(1, 1);
*
* 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);
*
P as(Class
proxyType) {
final boolean isMap = (object instanceof Map);
final InvocationHandler handler = new InvocationHandler() {
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] Simulate POJO behaviour on wrapped map objects
catch (ReflectException e) {
if (isMap) {
Map map = (Map) 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 (!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) 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 ? Object.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;
}
}