injectorimpl.java

Guice是轻量级的依赖注入框架。简而言之

/**
 * Copyright (C) 2006 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;

import com.google.inject.spi.SourceProviders;
import com.google.inject.util.GuiceFastClass;
import com.google.inject.util.Objects;
import com.google.inject.util.ReferenceCache;
import com.google.inject.util.StackTraceElements;
import com.google.inject.util.Strings;
import com.google.inject.util.ToStringBuilder;
import java.lang.annotation.Annotation;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import net.sf.cglib.reflect.FastClass;
import net.sf.cglib.reflect.FastMethod;

/**
 * Default {@link Injector} implementation.
 *
 * @author [e-mail] (Bob Lee)
 * @see BinderImpl
 */
class InjectorImpl implements Injector {

  /**
   * Maps between primitive types and their wrappers and vice versa.
   */
  private static final Map<Class<?>, Class<?>> PRIMITIVE_COUNTERPARTS;
  static {
    Map<Class<?>, Class<?>> primitiveToWrapper =
        new HashMap<Class<?>, Class<?>>() {{
          put(int.class, Integer.class);
          put(long.class, Long.class);
          put(boolean.class, Boolean.class);
          put(byte.class, Byte.class);
          put(short.class, Short.class);
          put(float.class, Float.class);
          put(double.class, Double.class);
          put(char.class, Character.class);
        }};

    Map<Class<?>, Class<?>> counterparts = new HashMap<Class<?>, Class<?>>();
    for (Map.Entry<Class<?>, Class<?>> entry : primitiveToWrapper.entrySet()) {
      Class<?> key = entry.getKey();
      Class<?> value = entry.getValue();
      counterparts.put(key, value);
      counterparts.put(value, key);
    }

    PRIMITIVE_COUNTERPARTS = Collections.unmodifiableMap(counterparts);
  }

  private static final Map<Class<?>, Converter<?>> PRIMITIVE_CONVERTERS
      = new PrimitiveConverters();

  final ConstructionProxyFactory constructionProxyFactory;
  final Map<Key<?>, BindingImpl<?>> bindings;
  final BindingsMultimap bindingsMultimap = new BindingsMultimap();
  final Map<Class<? extends Annotation>, Scope> scopes;

  ErrorHandler errorHandler = new InvalidErrorHandler();
  Object defaultSource = SourceProviders.UNKNOWN_SOURCE;

  InjectorImpl(ConstructionProxyFactory constructionProxyFactory,
      Map<Key<?>, BindingImpl<?>> bindings,
      Map<Class<? extends Annotation>, Scope> scopes) {
    this.constructionProxyFactory = constructionProxyFactory;
    this.bindings = bindings;
    this.scopes = scopes;
  }

  /**
   * Indexes bindings by type.
   */
  void index() {
    for (BindingImpl<?> binding : bindings.values()) {
      index(binding);
    }
  }

  <T> void index(BindingImpl<T> binding) {
    bindingsMultimap.put(binding.getKey().getTypeLiteral(), binding);
  }

  // not test-covered
  public <T> List<Binding<T>> findBindingsByType(TypeLiteral<T> type) {
    return Collections.<Binding<T>>unmodifiableList(
        bindingsMultimap.getAll(type));
  }

  // not test-covered
  <T> List<String> getNamesOfBindingAnnotations(TypeLiteral<T> type) {
    List<String> names = new ArrayList<String>();
    for (Binding<T> binding : findBindingsByType(type)) {
      Key<T> key = binding.getKey();
      if (!key.hasAnnotationType()) {
        names.add("[no annotation]");
      } else {
        names.add(key.getAnnotationName());
      }
    }
    return names;
  }

  /**
   * This is only used during Injector building.
   */
  void withDefaultSource(Object defaultSource, Runnable runnable) {
    Object previous = this.defaultSource;
    this.defaultSource = defaultSource;
    try {
      runnable.run();
    }
    finally {
      this.defaultSource = previous;
    }
  }

  void setErrorHandler(ErrorHandler errorHandler) {
    this.errorHandler = errorHandler;
  }

  <T> InternalFactory<? extends T> getInternalFactory(
      final Member member, Key<T> key) {
    // TODO: Clean up unchecked type warnings.

    // Do we have a factory for the specified type and name?
    BindingImpl<T> binding = getBinding(key);
    if (binding != null) {
      return binding.getInternalFactory();
    }

    Class<? super T> rawType = key.getTypeLiteral().getRawType();

    // Handle cases where T is a Provider<?>.
    if (rawType.equals(Provider.class)) {
      Type providerType = key.getTypeLiteral().getType();
      if (!(providerType instanceof ParameterizedType)) {
        // Raw Provider.
        return null;
      }
      Type entryType
          = ((ParameterizedType) providerType).getActualTypeArguments()[0];

      try {
        final Provider<?> provider = getProvider(key.ofType(entryType));
        return new InternalFactory<T>() {
          @SuppressWarnings("unchecked")
          public T get(InternalContext context) {
            return (T) provider;
          }
        };
      }
      catch (ConfigurationException e) {
        // Look for a factory bound to a key without annotation attributes if
        // necessary.
        if (key.hasAttributes()) {
          return getInternalFactory(member, key.withoutAttributes());
        }

        // End of the road.
        ErrorMessages.handleMissingBinding(errorHandler, member, key,
            getNamesOfBindingAnnotations(key.getTypeLiteral()));
        return invalidFactory();
      }
    }

    // Auto[un]box primitives.
    Class<?> primitiveCounterpart
        = PRIMITIVE_COUNTERPARTS.get(rawType);
    if (primitiveCounterpart != null) {
      BindingImpl<?> counterpartBinding
          = getBinding(key.ofType(primitiveCounterpart));
      if (counterpartBinding != null) {
        return (InternalFactory<? extends T>)
            counterpartBinding.getInternalFactory();
      }
    }

    // TODO: Should we try to convert from a String first, or should we look
    // for a binding to the annotation type sans attributes? Right now, we
    // convert from a String.

    // Can we convert from a String constant?
    Key<String> stringKey = key.ofType(String.class);
    BindingImpl<String> stringBinding = getBinding(stringKey);
    if (stringBinding != null && stringBinding.isConstant()) {
      // We don't need do pass in an InternalContext because we know this is
      // a ConstantFactory which will not use it.
      String value = stringBinding.getInternalFactory().get(null);

      // TODO: Generalize everything below here and enable users to plug in
      // their own converters.

      // Do we need a primitive?
      Converter<T> converter = (Converter<T>) PRIMITIVE_CONVERTERS.get(rawType);
      if (converter != null) {
        try {
          T t = converter.convert(member, key, value);
          return new ConstantFactory<T>(t);
        }
        catch (ConstantConversionException e) {
          return handleConstantConversionError(
              member, stringBinding, rawType, e);
        }
      }

      // Do we need an enum?
      if (Enum.class.isAssignableFrom(rawType)) {
        T t;
        try {
          t = (T) Enum.valueOf((Class) rawType, value);
        }
        catch (IllegalArgumentException e) {
          return handleConstantConversionError(
              member, stringBinding, rawType, e);
        }
        return new ConstantFactory<T>(t);
      }

      // Do we need a class?
      if (rawType == Class.class) {
        try {
          // TODO: Make sure we use the right classloader.
          return new ConstantFactory<T>((T) Class.forName(value));
        }
        catch (ClassNotFoundException e) {
          return handleConstantConversionError(
              member, stringBinding, rawType, e);
        }
      }
    }

    // Don't try to inject primitives, arrays, or enums.
    int modifiers = rawType.getModifiers();
    if (rawType.isArray() || rawType.isEnum() || rawType.isPrimitive()) {
      // Look for a factory bound to a key without annotation attributes if
      // necessary.
      if (key.hasAttributes()) {
        return getInternalFactory(member, key.withoutAttributes());
      }

      return null;
    }

    // We don't want to implicitly inject a member if we have a binding
    // annotation.
    if (key.hasAnnotationType()) {
      // Look for a factory bound to a key without annotation attributes if
      // necessary.
      if (key.hasAttributes()) {
        return getInternalFactory(member, key.withoutAttributes());
      }

      return null;
    }

    // Last resort: inject the type itself.
    if (member != null) {
      // If we're injecting into a member, include it in the error messages.
      final ErrorHandler previous = this.errorHandler;
      this.errorHandler = new AbstractErrorHandler() {
        public void handle(Object source, String message) {
          previous.handle(source, "Error while injecting at "
              + StackTraceElements.forMember(member) + ": " + message);
        }
      };
      try {
        // note: intelliJ thinks this cast is superfluous, but is it?
        return (InternalFactory<? extends T>) getImplicitBinding(member,
            rawType, null);
      }
      finally {
        this.errorHandler = previous;
      }
    }
    // note: intelliJ thinks this cast is superfluous, but is it?
    return (InternalFactory<? extends T>) getImplicitBinding(member, rawType,
        null);
  }

  private <T> InternalFactory<T> handleConstantConversionError(
      Member member, Binding<String> stringBinding, Class<?> rawType,
      Exception e) {
    errorHandler.handle(
        StackTraceElements.forMember(member),
        ErrorMessages.CONSTANT_CONVERSION_ERROR,
        stringBinding.getSource(),
        rawType,
        e.getMessage());
    return invalidFactory();
  }

  /**
   * Field and method injectors.
   */
  final Map<Class<?>, List<SingleMemberInjector>> injectors
      = new ReferenceCache<Class<?>, List<SingleMemberInjector>>() {
    protected List<SingleMemberInjector> create(Class<?> key) {
      List<SingleMemberInjector> injectors
          = new ArrayList<SingleMemberInjector>();
      addInjectors(key, injectors);
      return injectors;
    }
  };

  /**
   * Recursively adds injectors for fields and methods from the given class to
   * the given list. Injects parent classes before sub classes.
   */
  void addInjectors(Class clazz, List<SingleMemberInjector> injectors) {
    if (clazz == Object.class) {
      return;