com.google.inject.internal.DefaultConstructionProxyFactory Maven / Gradle / Ivy

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package com.google.inject.internal;

import com.google.inject.spi.InjectionPoint;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;

/**
 * Produces construction proxies that invoke the class constructor.
 */
final class DefaultConstructionProxyFactory implements ConstructionProxyFactory {

    private final InjectionPoint injectionPoint;

    /**
     * @param injectionPoint an injection point whose member is a constructor of {@code T}.
     */
    DefaultConstructionProxyFactory(InjectionPoint injectionPoint) {
        this.injectionPoint = injectionPoint;
    }

    public ConstructionProxy create() {
        @SuppressWarnings("unchecked") // the injection point is for a constructor of T
        final Constructor constructor = (Constructor) injectionPoint.getMember();

        if (!Modifier.isPublic(constructor.getDeclaringClass().getModifiers()) ||
                !Modifier.isPublic(constructor.getModifiers())) {
            constructor.setAccessible(true);
        }

        return new ConstructionProxy() {
            public T newInstance(Object... arguments) throws InvocationTargetException {
                try {
                    return constructor.newInstance(arguments);
                } catch (InstantiationException | IllegalAccessException e) {
                    throw new AssertionError(e); // shouldn't happen, we know this is a concrete type
                }
            }

            @Override
            public InjectionPoint getInjectionPoint() {
                return injectionPoint;
            }

            @Override
            public Constructor getConstructor() {
                return constructor;
            }
        };
    }
}