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Java example source code file (BindingProcessor.java)

This example Java source code file (BindingProcessor.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

bindingprocessor, boolean, cannot, factoryproxy, illegalargumentexception, initializable, internalfactory, key, override, providerinstancebinding, providermethod, set, suppresswarnings, util

The BindingProcessor.java Java example source code

/**
 * Copyright (C) 2008 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject.internal;

import com.google.inject.Binder;
import com.google.inject.Binding;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.spi.ConstructorBinding;
import com.google.inject.spi.ConvertedConstantBinding;
import com.google.inject.spi.ExposedBinding;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.InstanceBinding;
import com.google.inject.spi.LinkedKeyBinding;
import com.google.inject.spi.PrivateElements;
import com.google.inject.spi.ProviderBinding;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderKeyBinding;
import com.google.inject.spi.UntargettedBinding;

import java.util.Set;

/**
 * Handles {@link Binder#bind} and {@link Binder#bindConstant} elements.
 *
 * @author crazybob@google.com (Bob Lee)
 * @author jessewilson@google.com (Jesse Wilson)
 */
final class BindingProcessor extends AbstractBindingProcessor {

  private final Initializer initializer;

  BindingProcessor(Errors errors, Initializer initializer, ProcessedBindingData bindingData) {
    super(errors, bindingData);
    this.initializer = initializer;
  }

  @Override public <T> Boolean visit(Binding command) {
    Class<?> rawType = command.getKey().getTypeLiteral().getRawType();
    if (Void.class.equals(rawType)) {
      if (command instanceof ProviderInstanceBinding
          && ((ProviderInstanceBinding) command).getUserSuppliedProvider()
              instanceof ProviderMethod) {
        errors.voidProviderMethod();
      } else {
        errors.missingConstantValues();
      }
      return true;
    }
    
    if (rawType == Provider.class) {
      errors.bindingToProvider();
      return true;
    }
    
    return command.acceptTargetVisitor(new Processor<T, Boolean>((BindingImpl)command) {
      @Override
      public Boolean visit(ConstructorBinding<? extends T> binding) {
        prepareBinding();
        try {
          ConstructorBindingImpl<T> onInjector = ConstructorBindingImpl.create(injector, key, 
              binding.getConstructor(), source, scoping, errors, false, false);
          scheduleInitialization(onInjector);
          putBinding(onInjector);
        } catch (ErrorsException e) {
          errors.merge(e.getErrors());
          putBinding(invalidBinding(injector, key, source));
        }
        return true;
      }

      @Override
      public Boolean visit(InstanceBinding<? extends T> binding) {
        prepareBinding();
        Set<InjectionPoint> injectionPoints = binding.getInjectionPoints();
        T instance = binding.getInstance();
        @SuppressWarnings("unchecked") // safe to cast to binding<T> because
                                       // the processor was constructed w/ it
        Initializable<T> ref = initializer.requestInjection(
            injector, instance, (Binding<T>) binding, source, injectionPoints);
        ConstantFactory<? extends T> factory = new ConstantFactory(ref);
        InternalFactory<? extends T> scopedFactory
            = Scoping.scope(key, injector, factory, source, scoping);
        putBinding(new InstanceBindingImpl<T>(injector, key, source, scopedFactory, injectionPoints,
            instance));
        return true;
      }

      @Override
      public Boolean visit(ProviderInstanceBinding<? extends T> binding) {
        prepareBinding();
        javax.inject.Provider<? extends T> provider = binding.getUserSuppliedProvider();
        // TODO(lukes): add support for multibinder/mapbinder/optionalbinder here as well
        // this may require extracting some generic interface instead of testing for specific
        // implementations.
        if (provider instanceof ProviderMethod) {
          @SuppressWarnings("unchecked")
          ProviderMethod<T> asProviderMethod = (ProviderMethod) provider;
          return visitProviderMethod(asProviderMethod);
        }
        Set<InjectionPoint> injectionPoints = binding.getInjectionPoints();
        Initializable<? extends javax.inject.Provider initializable =
            initializer.<javax.inject.ProviderrequestInjection(
                injector, provider, null, source, injectionPoints);
        // always visited with Binding<T>
        @SuppressWarnings("unchecked") 
        InternalFactory<T> factory = new InternalFactoryToInitializableAdapter(
            initializable, source,
            injector.provisionListenerStore.get((ProviderInstanceBinding<T>)binding));
        InternalFactory<? extends T> scopedFactory
            = Scoping.scope(key, injector, factory, source, scoping);
        putBinding(new ProviderInstanceBindingImpl<T>(injector, key, source, scopedFactory, scoping,
            provider, injectionPoints));
        return true;
      }

      @Override
      public Boolean visit(ProviderKeyBinding<? extends T> binding) {
        prepareBinding();
        Key<? extends javax.inject.Provider providerKey = binding.getProviderKey();
        // always visited with Binding<T>
        @SuppressWarnings("unchecked") 
        BoundProviderFactory<T> boundProviderFactory = new BoundProviderFactory(
            injector, providerKey, source,
            injector.provisionListenerStore.get((ProviderKeyBinding<T>) binding));
        bindingData.addCreationListener(boundProviderFactory);
        InternalFactory<? extends T> scopedFactory = Scoping.scope(
            key, injector, (InternalFactory<? extends T>) boundProviderFactory, source, scoping);
        putBinding(new LinkedProviderBindingImpl<T>(
            injector, key, source, scopedFactory, scoping, providerKey));
        return true;
      }

      @Override
      public Boolean visit(LinkedKeyBinding<? extends T> binding) {
        prepareBinding();
        Key<? extends T> linkedKey = binding.getLinkedKey();
        if (key.equals(linkedKey)) {
          errors.recursiveBinding();
        }

        FactoryProxy<T> factory = new FactoryProxy(injector, key, linkedKey, source);
        bindingData.addCreationListener(factory);
        InternalFactory<? extends T> scopedFactory
            = Scoping.scope(key, injector, factory, source, scoping);
        putBinding(
            new LinkedBindingImpl<T>(injector, key, source, scopedFactory, scoping, linkedKey));
        return true;
      }
      
      /** Handle ProviderMethods specially. */
      private Boolean visitProviderMethod(ProviderMethod<T> provider) {
        BindingImpl<T> binding = 
            ProviderMethod.createBinding(injector, key, provider, source, scoping);
        scheduleInitialization(binding);
        putBinding(binding);
        return true;
      }

      @Override
      public Boolean visit(UntargettedBinding<? extends T> untargetted) {
        return false;
      }

      @Override
      public Boolean visit(ExposedBinding<? extends T> binding) {
        throw new IllegalArgumentException("Cannot apply a non-module element");
      }
      
      @Override
      public Boolean visit(ConvertedConstantBinding<? extends T> binding) {
        throw new IllegalArgumentException("Cannot apply a non-module element");
      }
      
      @Override
      public Boolean visit(ProviderBinding<? extends T> binding) {
        throw new IllegalArgumentException("Cannot apply a non-module element");
      }
      
      @Override
      protected Boolean visitOther(Binding<? extends T> binding) {
        throw new IllegalStateException("BindingProcessor should override all visitations");
      }
    });
  }

  @Override public Boolean visit(PrivateElements privateElements) {
    for (Key<?> key : privateElements.getExposedKeys()) {
      bindExposed(privateElements, key);
    }
    return false; // leave the private elements for the PrivateElementsProcessor to handle
  }

  private <T> void bindExposed(PrivateElements privateElements, Key key) {
    ExposedKeyFactory<T> exposedKeyFactory = new ExposedKeyFactory(key, privateElements);
    bindingData.addCreationListener(exposedKeyFactory);
    putBinding(new ExposedBindingImpl<T>(
        injector, privateElements.getExposedSource(key), key, exposedKeyFactory, privateElements));
  }
}

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