get Matching Accessible Method

Description

Demo Code

/*//w w w.j av a2  s. c o  m
 **        DroidPlugin Project
 **
 ** Copyright(c) 2015 Andy Zhang <zhangyong232@gmail.com>
 **
 ** This file is part of DroidPlugin.
 **
 ** DroidPlugin is free software: you can redistribute it and/or
 ** modify it under the terms of the GNU Lesser General Public
 ** License as published by the Free Software Foundation, either
 ** version 3 of the License, or (at your option) any later version.
 **
 ** DroidPlugin is distributed in the hope that it will be useful,
 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 ** Lesser General Public License for more details.
 **
 ** You should have received a copy of the GNU Lesser General Public
 ** License along with DroidPlugin.  If not, see <http://www.gnu.org/licenses/lgpl.txt>
 **
 **/
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;

public class Main{
    private static Map<String, Method> sMethodCache = new HashMap<String, Method>();
    private static Method getMatchingAccessibleMethod(final Class<?> cls,
            final String methodName, final Class<?>... parameterTypes) {

        String key = getKey(cls, methodName, parameterTypes);
        Method cachedMethod;
        synchronized (sMethodCache) {
            cachedMethod = sMethodCache.get(key);
        }
        if (cachedMethod != null) {
            if (!cachedMethod.isAccessible()) {
                cachedMethod.setAccessible(true);
            }
            return cachedMethod;
        }

        try {
            final Method method = cls.getMethod(methodName, parameterTypes);
            MemberUtils.setAccessibleWorkaround(method);
            synchronized (sMethodCache) {
                sMethodCache.put(key, method);
            }
            return method;
        } catch (final NoSuchMethodException e) { // NOPMD - Swallow the exception
        }
        // search through all methods
        Method bestMatch = null;
        final Method[] methods = cls.getMethods();
        for (final Method method : methods) {
            // compare name and parameters
            if (method.getName().equals(methodName)
                    && MemberUtils.isAssignable(parameterTypes,
                            method.getParameterTypes(), true)) {
                // get accessible version of method
                final Method accessibleMethod = getAccessibleMethod(method);
                if (accessibleMethod != null
                        && (bestMatch == null || MemberUtils
                                .compareParameterTypes(accessibleMethod
                                        .getParameterTypes(), bestMatch
                                        .getParameterTypes(),
                                        parameterTypes) < 0)) {
                    bestMatch = accessibleMethod;
                }
            }
        }
        if (bestMatch != null) {
            MemberUtils.setAccessibleWorkaround(bestMatch);
        }
        synchronized (sMethodCache) {
            sMethodCache.put(key, bestMatch);
        }
        return bestMatch;
    }
    private static String getKey(final Class<?> cls,
            final String methodName, final Class<?>... parameterTypes) {
        StringBuilder sb = new StringBuilder();
        sb.append(cls.toString()).append("#").append(methodName);
        if (parameterTypes != null && parameterTypes.length > 0) {
            for (Class<?> parameterType : parameterTypes) {
                sb.append(parameterType.toString()).append("#");
            }
        } else {
            sb.append(Void.class.toString());
        }
        return sb.toString();
    }
    private static boolean isAccessible(final Class<?> type) {
        Class<?> cls = type;
        while (cls != null) {
            if (!Modifier.isPublic(cls.getModifiers())) {
                return false;
            }
            cls = cls.getEnclosingClass();
        }
        return true;
    }
    private static Method getAccessibleMethod(Method method) {
        if (!MemberUtils.isAccessible(method)) {
            return null;
        }
        // If the declaring class is public, we are done
        final Class<?> cls = method.getDeclaringClass();
        if (Modifier.isPublic(cls.getModifiers())) {
            return method;
        }
        final String methodName = method.getName();
        final Class<?>[] parameterTypes = method.getParameterTypes();

        // Check the implemented interfaces and subinterfaces
        method = getAccessibleMethodFromInterfaceNest(cls, methodName,
                parameterTypes);

        // Check the superclass chain
        if (method == null) {
            method = getAccessibleMethodFromSuperclass(cls, methodName,
                    parameterTypes);
        }
        return method;
    }
    public static Method getAccessibleMethod(final Class<?> cls,
            final String methodName, final Class<?>... parameterTypes)
            throws NoSuchMethodException {
        String key = getKey(cls, methodName, parameterTypes);
        Method method;
        synchronized (sMethodCache) {
            method = sMethodCache.get(key);
        }
        if (method != null) {
            if (!method.isAccessible()) {
                method.setAccessible(true);
            }
            return method;
        }

        Method accessibleMethod = getAccessibleMethod(cls.getMethod(
                methodName, parameterTypes));
        synchronized (sMethodCache) {
            sMethodCache.put(key, accessibleMethod);
        }
        return accessibleMethod;

    }
    private static Method getAccessibleMethodFromInterfaceNest(
            Class<?> cls, final String methodName,
            final Class<?>... parameterTypes) {
        // Search up the superclass chain
        for (; cls != null; cls = cls.getSuperclass()) {

            // Check the implemented interfaces of the parent class
            final Class<?>[] interfaces = cls.getInterfaces();
            for (int i = 0; i < interfaces.length; i++) {
                // Is this interface public?
                if (!Modifier.isPublic(interfaces[i].getModifiers())) {
                    continue;
                }
                // Does the method exist on this interface?
                try {
                    return interfaces[i].getDeclaredMethod(methodName,
                            parameterTypes);
                } catch (final NoSuchMethodException e) { // NOPMD
                    /*
                     * Swallow, if no method is found after the loop then this
                     * method returns null.
                     */
                }
                // Recursively check our parent interfaces
                Method method = getAccessibleMethodFromInterfaceNest(
                        interfaces[i], methodName, parameterTypes);
                if (method != null) {
                    return method;
                }
            }
        }
        return null;
    }
    private static Method getAccessibleMethodFromSuperclass(
            final Class<?> cls, final String methodName,
            final Class<?>... parameterTypes) {
        Class<?> parentClass = cls.getSuperclass();
        while (parentClass != null) {
            if (Modifier.isPublic(parentClass.getModifiers())) {
                try {
                    return parentClass
                            .getMethod(methodName, parameterTypes);
                } catch (final NoSuchMethodException e) {
                    return null;
                }
            }
            parentClass = parentClass.getSuperclass();
        }
        return null;
    }
}
get Matching Accessible Method - Java Reflection

Description

Demo Code

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