ch.jalu.injector.handlers.preconstruct.PreConstructPackageValidator Maven / Gradle / Ivy

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package ch.jalu.injector.handlers.preconstruct;

import ch.jalu.injector.context.UnresolvedInstantiationContext;
import ch.jalu.injector.exceptions.InjectorException;

/**
 * Validates the package of a parameter type to ensure that it is part of the allowed packages.
 * This ensures that we don't try to instantiate things that are beyond our reach in case some
 * external dependency has not been registered by accident.
 */
public class PreConstructPackageValidator implements PreConstructHandler {

    private final String rootPackage;

    /**
     * Constructor.
     *
     * @param rootPackage the main package under which classes may be instantiated
     */
    public PreConstructPackageValidator(String rootPackage) {
        this.rootPackage = rootPackage;
    }

    @Override
    public  void accept(UnresolvedInstantiationContext context) {
        final Class clazz = context.getMappedClass();
        if (clazz.getPackage() == null) {
            String detail = clazz.isPrimitive()
                ? "Primitive types must be provided explicitly (or use an annotation)."
                : clazz.isArray()
                    ? "Unknown how to inject array classes (did you forget to add a custom handler?)"
                    : "";
            throw new InjectorException("Cannot instantiate '" + clazz + "'. " + detail);
        }
        String packageName = clazz.getPackage().getName();
        if (!packageName.startsWith(rootPackage)) {
            throw new InjectorException("Class '" + clazz + "' with package '" + packageName + "' is outside of the "
                + "allowed packages. It must be provided explicitly or the package must be passed to the constructor.");
        }
    }
}