ReflectionHelpers.java

import com.google.common.base.Preconditions;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import lombok.AllArgsConstructor;
import lombok.EqualsAndHashCode;

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

public class ReflectionHelpers {
    private static Table<Class<?>, String, Method> cachedNoArgsMethods = HashBasedTable.create();
    private static Table<Class<?>, MethodArgs, Method> cachedArgsMethods = HashBasedTable.create();
    private static Table<Class<?>, String, Field> cachedFields = HashBasedTable.create();

    public static Method getCachedMethod(Class<?> clazz, String name) throws NoSuchMethodException {
        Preconditions.checkNotNull(clazz, "clazz");
        Preconditions.checkNotNull(name, "name");

        if (cachedNoArgsMethods.contains(clazz, name))
            return cachedNoArgsMethods.get(clazz, name);

        Method method = clazz.getMethod(name);
        method.setAccessible(true);

        cachedNoArgsMethods.put(clazz, name, method);

        return method;
    }

    public static Method getCachedMethod(Class<?> clazz, String name, Class<?>... args) throws NoSuchMethodException {
        Preconditions.checkNotNull(clazz, "clazz");
        Preconditions.checkNotNull(name, "name");

        MethodArgs args1 = new MethodArgs(name, args);

        if (cachedArgsMethods.contains(clazz, args1))
            return cachedArgsMethods.get(clazz, args1);

        Method method = clazz.getMethod(name, args);
        method.setAccessible(true);

        cachedArgsMethods.put(clazz, args1, method);

        return method;
    }

    public static Field getCachedField(Class<?> clazz, String name) throws NoSuchFieldException {
        Preconditions.checkNotNull(clazz, "clazz");
        Preconditions.checkNotNull(name, "name");

        if (cachedFields.contains(clazz, name))
            return cachedFields.get(clazz, name);

        Field field = clazz.getField(name);
        field.setAccessible(true);

        cachedFields.put(clazz, name, field);

        return field;
    }

    @AllArgsConstructor
    @EqualsAndHashCode
    private static class MethodArgs {
        private final String name;
        private final Class<?>[] args;
    }
}