ClassLoaderUtil.java

/**
 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
 */

package net.sourceforge.pmd.dcd;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

/**
 * ClassLoader utilities. Useful for extracting additional details from a class
 * hierarchy beyond the basic standard Java Reflection APIs.
 */
public class ClassLoaderUtil {

    public static final String CLINIT = "<clinit>";

    public static final String INIT = "<init>";

    private ClassLoaderUtil() { }

    public static String fromInternalForm(String internalForm) {
        return internalForm.replace('/', '.');
    }

    public static String toInternalForm(String internalForm) {
        return internalForm.replace('.', '/');
    }

    public static Class<?> getClass(String name) {
        try {
            return ClassLoaderUtil.class.getClassLoader().loadClass(name);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (NoClassDefFoundError e) {
            throw new RuntimeException(e);
        }
    }

    public static Field getField(Class<?> type, String name) {
        try {
            return myGetField(type, name);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException(e);
        }
    }

    private static Field myGetField(Class<?> type, String name) throws NoSuchFieldException {
        // Scan the type hierarchy just like Class.getField(String) using
        // Class.getDeclaredField(String)
        try {
            return type.getDeclaredField(name);
        } catch (NoSuchFieldException e) {
            // Try the super interfaces
            for (Class<?> superInterface : type.getInterfaces()) {
                try {
                    return myGetField(superInterface, name);
                } catch (NoSuchFieldException e2) {
                    // Okay
                }
            }
            // Try the super classes
            if (type.getSuperclass() != null) {
                return myGetField(type.getSuperclass(), name);
            } else {
                throw new NoSuchFieldException(type.getName() + "." + name);
            }
        }
    }

    public static Method getMethod(Class<?> type, String name, Class<?>... parameterTypes) {
        try {
            return myGetMethod(type, name, parameterTypes);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        }
    }

    private static Method myGetMethod(Class<?> type, String name, Class<?>... parameterTypes)
            throws NoSuchMethodException {
        // Scan the type hierarchy just like Class.getMethod(String, Class[])
        // using Class.getDeclaredMethod(String, Class[])
        // System.out.println("type: " + type);
        // System.out.println("name: " + name);
        // System.out
        // .println("parameterTypes: " + Arrays.toString(parameterTypes));
        try {
            // System.out.println("Checking getDeclaredMethod");
            // for (Method m : type.getDeclaredMethods()) {
            // System.out.println("\t" + m);
            // }
            return type.getDeclaredMethod(name, parameterTypes);
        } catch (NoSuchMethodException e) {
            try {
                // Try the super classes
                if (type.getSuperclass() != null) {
                    // System.out.println("Checking super: "
                    // + type.getSuperclass());
                    return myGetMethod(type.getSuperclass(), name, parameterTypes);
                }
            } catch (NoSuchMethodException e2) {
                // Okay
            }
            // Try the super interfaces
            for (Class<?> superInterface : type.getInterfaces()) {
                try {
                    // System.out.println("Checking super interface: "
                    // + superInterface);
                    return myGetMethod(superInterface, name, parameterTypes);
                } catch (NoSuchMethodException e3) {
                    // Okay
                }
            }
            throw new NoSuchMethodException(type.getName() + '.' + getMethodSignature(name, parameterTypes));
        }
    }

    public static Constructor<?> getConstructor(Class<?> type, String name, Class<?>... parameterTypes) {
        try {
            return type.getDeclaredConstructor(parameterTypes);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        }
    }

    public static String getMethodSignature(String name, Class<?>... parameterTypes) {
        StringBuilder builder = new StringBuilder(name);
        if (!(name.equals(CLINIT) || name.equals(INIT))) {
            builder.append('(');
            if (parameterTypes != null && parameterTypes.length > 0) {
                builder.append(parameterTypes[0].getName());
                for (int i = 1; i < parameterTypes.length; i++) {
                    builder.append(", ").append(parameterTypes[i].getName());
                }
            }
            builder.append(')');
        }
        return builder.toString();
    }

    public static Class<?>[] getParameterTypes(String... parameterTypeNames) {
        Class<?>[] parameterTypes = new Class[parameterTypeNames.length];
        for (int i = 0; i < parameterTypeNames.length; i++) {
            parameterTypes[i] = getClass(parameterTypeNames[i]);
        }
        return parameterTypes;
    }

    public static boolean isOverridenMethod(Class<?> clazz, Method method, boolean checkThisClass) {
        try {
            if (checkThisClass) {
                clazz.getDeclaredMethod(method.getName(), method.getParameterTypes());
                return true;
            }
        } catch (NoSuchMethodException e) {
        }
        // Check super class
        if (clazz.getSuperclass() != null) {
            if (isOverridenMethod(clazz.getSuperclass(), method, true)) {
                return true;
            }
        }
        // Check interfaces
        for (Class<?> anInterface : clazz.getInterfaces()) {
            if (isOverridenMethod(anInterface, method, true)) {
                return true;
            }
        }
        return false;
    }
}