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Java example source code file (ConstructorBindingImpl.java)

This example Java source code file (ConstructorBindingImpl.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, class, constructorbindingimpl, constructorinjector, errorsexception, factory, injectionpoint, internalfactory, key, object, override, reflection, scoping, set, suppresswarnings, util

The ConstructorBindingImpl.java Java example source code

 * Copyright (C) 2007 Google Inc.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package com.google.inject.internal;

import static com.google.common.base.Preconditions.checkState;
import static com.google.inject.internal.Annotations.findScopeAnnotation;

import com.google.common.base.MoreObjects;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.ConfigurationException;
import com.google.inject.Inject;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.internal.util.Classes;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.ConstructorBinding;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.InjectionPoint;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.List;
import java.util.Map;
import java.util.Set;

final class ConstructorBindingImpl<T> extends BindingImpl
    implements ConstructorBinding<T>, DelayedInitialize {

  private final Factory<T> factory;
  private final InjectionPoint constructorInjectionPoint;

  private ConstructorBindingImpl(InjectorImpl injector, Key<T> key, Object source,
      InternalFactory<? extends T> scopedFactory, Scoping scoping, Factory factory,
      InjectionPoint constructorInjectionPoint) {
    super(injector, key, source, scopedFactory, scoping);
    this.factory = factory;
    this.constructorInjectionPoint = constructorInjectionPoint;

  public ConstructorBindingImpl(Key<T> key, Object source, Scoping scoping,
      InjectionPoint constructorInjectionPoint, Set<InjectionPoint> injectionPoints) {
    super(source, key, scoping);
    this.factory = new Factory<T>(false, key);
    ConstructionProxy<T> constructionProxy
        = new DefaultConstructionProxyFactory<T>(constructorInjectionPoint).create();
    this.constructorInjectionPoint = constructorInjectionPoint;
    factory.constructorInjector = new ConstructorInjector<T>(
        injectionPoints, constructionProxy, null, null);

   * @param constructorInjector the constructor to use, or {@code null} to use the default.
   * @param failIfNotLinked true if this ConstructorBindingImpl's InternalFactory should
   *                             only succeed if retrieved from a linked binding
  static <T> ConstructorBindingImpl create(InjectorImpl injector, Key key,
      InjectionPoint constructorInjector, Object source, Scoping scoping, Errors errors,
      boolean failIfNotLinked, boolean failIfNotExplicit)
      throws ErrorsException {
    int numErrors = errors.size();

    @SuppressWarnings("unchecked") // constructorBinding guarantees type is consistent
    Class<? super T> rawType = constructorInjector == null
        ? key.getTypeLiteral().getRawType()
        : (Class) constructorInjector.getDeclaringType().getRawType();

    // We can't inject abstract classes.
    if (Modifier.isAbstract(rawType.getModifiers())) {

    // Error: Inner class.
    if (Classes.isInnerClass(rawType)) {


    // Find a constructor annotated @Inject
    if (constructorInjector == null) {
      try {
        constructorInjector = InjectionPoint.forConstructorOf(key.getTypeLiteral());
        if (failIfNotExplicit && !hasAtInject((Constructor) constructorInjector.getMember())) {
      } catch (ConfigurationException e) {
        throw errors.merge(e.getErrorMessages()).toException();

    // if no scope is specified, look for a scoping annotation on the concrete class
    if (!scoping.isExplicitlyScoped()) {
      Class<?> annotatedType = constructorInjector.getMember().getDeclaringClass();
      Class<? extends Annotation> scopeAnnotation = findScopeAnnotation(errors, annotatedType);
      if (scopeAnnotation != null) {
        scoping = Scoping.makeInjectable(Scoping.forAnnotation(scopeAnnotation),
            injector, errors.withSource(rawType));


    Factory<T> factoryFactory = new Factory(failIfNotLinked, key);
    InternalFactory<? extends T> scopedFactory
        = Scoping.scope(key, injector, factoryFactory, source, scoping);

    return new ConstructorBindingImpl<T>(
        injector, key, source, scopedFactory, scoping, factoryFactory, constructorInjector);

  /** Returns true if the inject annotation is on the constructor. */
  private static boolean hasAtInject(Constructor cxtor) {
    return cxtor.isAnnotationPresent(Inject.class)
        || cxtor.isAnnotationPresent(javax.inject.Inject.class);

  @SuppressWarnings("unchecked") // the result type always agrees with the ConstructorInjector type
  public void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
    factory.constructorInjector =
        (ConstructorInjector<T>) injector.constructors.get(constructorInjectionPoint, errors);
    factory.provisionCallback =

  /** True if this binding has been initialized and is ready for use. */
  boolean isInitialized() {
    return factory.constructorInjector != null;

  /** Returns an injection point that can be used to clean up the constructor store. */
  InjectionPoint getInternalConstructor() {
    if(factory.constructorInjector != null) {
      return factory.constructorInjector.getConstructionProxy().getInjectionPoint();
    } else {
      return constructorInjectionPoint;

  /** Returns a set of dependencies that can be iterated over to clean up stray JIT bindings. */
  Set<Dependency getInternalDependencies() {
    ImmutableSet.Builder<InjectionPoint> builder = ImmutableSet.builder();
    if(factory.constructorInjector == null) {
      // If the below throws, it's OK -- we just ignore those dependencies, because no one
      // could have used them anyway.
      try {
      } catch(ConfigurationException ignored) {}
    } else {

    return Dependency.forInjectionPoints(builder.build());

  public <V> V acceptTargetVisitor(BindingTargetVisitor visitor) {
    checkState(factory.constructorInjector != null, "not initialized");
    return visitor.visit(this);

  public InjectionPoint getConstructor() {
    checkState(factory.constructorInjector != null, "Binding is not ready");
    return factory.constructorInjector.getConstructionProxy().getInjectionPoint();

  public Set<InjectionPoint> getInjectableMembers() {
    checkState(factory.constructorInjector != null, "Binding is not ready");
    return factory.constructorInjector.getInjectableMembers();

  public Map<Method, List getMethodInterceptors() {
    checkState(factory.constructorInjector != null, "Binding is not ready");
    return factory.constructorInjector.getConstructionProxy().getMethodInterceptors();

  public Set<Dependency getDependencies() {
    return Dependency.forInjectionPoints(new ImmutableSet.Builder<InjectionPoint>()

  @Override protected BindingImpl<T> withScoping(Scoping scoping) {
    return new ConstructorBindingImpl<T>(
        null, getKey(), getSource(), factory, scoping, factory, constructorInjectionPoint);

  @Override protected BindingImpl<T> withKey(Key key) {
    return new ConstructorBindingImpl<T>(
        null, key, getSource(), factory, getScoping(), factory, constructorInjectionPoint);

  @SuppressWarnings("unchecked") // the raw constructor member and declaring type always agree
  public void applyTo(Binder binder) {
    InjectionPoint constructor = getConstructor();
        (Constructor) getConstructor().getMember(), (TypeLiteral) constructor.getDeclaringType()));

  @Override public String toString() {
    return MoreObjects.toStringHelper(ConstructorBinding.class)
        .add("key", getKey())
        .add("source", getSource())
        .add("scope", getScoping())

  public boolean equals(Object obj) {
    if(obj instanceof ConstructorBindingImpl) {
      ConstructorBindingImpl<?> o = (ConstructorBindingImpl)obj;
      return getKey().equals(o.getKey())
        && getScoping().equals(o.getScoping())
        && Objects.equal(constructorInjectionPoint, o.constructorInjectionPoint);
    } else {
      return false;

  public int hashCode() {
    return Objects.hashCode(getKey(), getScoping(), constructorInjectionPoint);

  private static class Factory<T> implements InternalFactory {
    private final boolean failIfNotLinked;
    private final Key<?> key;
    private ConstructorInjector<T> constructorInjector;
    private ProvisionListenerStackCallback<T> provisionCallback;

    Factory(boolean failIfNotLinked, Key<?> key) {
      this.failIfNotLinked = failIfNotLinked;
      this.key = key;

    public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
        throws ErrorsException {
      checkState(constructorInjector != null, "Constructor not ready");

      if(failIfNotLinked && !linked) {
        throw errors.jitDisabled(key).toException();

      // This may not actually be safe because it could return a super type of T (if that's all the
      // client needs), but it should be OK in practice thanks to the wonders of erasure.
      return (T) constructorInjector.construct(errors, context,
          dependency.getKey().getTypeLiteral().getRawType(), provisionCallback);

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