containerimpl.java

在Struts2中的jar包xwork的源代码.版本为2.0.7

/**
 * 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.opensymphony.xwork2.inject;

import com.opensymphony.xwork2.inject.util.ReferenceCache;

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.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;
import java.io.Serializable;

/**
 * Default {@link Container} implementation.
 *
 * @see ContainerBuilder
 * @author [e-mail] (Bob Lee)
 */
class ContainerImpl implements Container {

  final Map<Key<?>, InternalFactory<?>> factories;
  final Map<Class<?>,Set<String>> factoryNamesByType;

  ContainerImpl(Map<Key<?>, InternalFactory<?>> factories) {
    this.factories = factories;
    Map<Class<?>,Set<String>> map = new HashMap<Class<?>,Set<String>>();
    for (Key<?> key : factories.keySet()) {
      Set<String> names = map.get(key.getType());
      if (names == null) {
        names = new HashSet<String>();
        map.put(key.getType(), names);
      }
      names.add(key.getName());
    }
    
    for (Entry<Class<?>,Set<String>> entry : map.entrySet()) {
      entry.setValue(Collections.unmodifiableSet(entry.getValue()));
    }
    
    this.factoryNamesByType = Collections.unmodifiableMap(map);
  }

  @SuppressWarnings("unchecked")
  <T> InternalFactory<? extends T> getFactory(Key<T> key) {
    return (InternalFactory<T>) factories.get(key);
  }

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

    // Add injectors for superclass first.
    addInjectors(clazz.getSuperclass(), injectors);

    // TODO (crazybob): Filter out overridden members.
    addInjectorsForFields(clazz.getDeclaredFields(), false, injectors);
    addInjectorsForMethods(clazz.getDeclaredMethods(), false, injectors);
  }

  void injectStatics(List<Class<?>> staticInjections) {
    final List<Injector> injectors = new ArrayList<Injector>();

    for (Class<?> clazz : staticInjections) {
      addInjectorsForFields(clazz.getDeclaredFields(), true, injectors);
      addInjectorsForMethods(clazz.getDeclaredMethods(), true, injectors);
    }

    callInContext(new ContextualCallable<Void>() {
      public Void call(InternalContext context) {
        for (Injector injector : injectors) {
          injector.inject(context, null);
        }
        return null;
      }
    });
  }

  void addInjectorsForMethods(Method[] methods, boolean statics,
      List<Injector> injectors) {
    addInjectorsForMembers(Arrays.asList(methods), statics, injectors,
        new InjectorFactory<Method>() {
          public Injector create(ContainerImpl container, Method method,
              String name) throws MissingDependencyException {
            return new MethodInjector(container, method, name);
          }
        });
  }

  void addInjectorsForFields(Field[] fields, boolean statics,
      List<Injector> injectors) {
    addInjectorsForMembers(Arrays.asList(fields), statics, injectors,
        new InjectorFactory<Field>() {
          public Injector create(ContainerImpl container, Field field,
              String name) throws MissingDependencyException {
            return new FieldInjector(container, field, name);
          }
        });
  }

  <M extends Member & AnnotatedElement> void addInjectorsForMembers(
      List<M> members, boolean statics, List<Injector> injectors,
      InjectorFactory<M> injectorFactory) {
    for (M member : members) {
      if (isStatic(member) == statics) {
        Inject inject = member.getAnnotation(Inject.class);
        if (inject != null) {
          try {
            injectors.add(injectorFactory.create(this, member, inject.value()));
          } catch (MissingDependencyException e) {
            if (inject.required()) {
              throw new DependencyException(e);
            }
          }
        }
      }
    }
  }

  interface InjectorFactory<M extends Member & AnnotatedElement> {
    Injector create(ContainerImpl container, M member, String name)
        throws MissingDependencyException;
  }

  private boolean isStatic(Member member) {
    return Modifier.isStatic(member.getModifiers());
  }

  static class FieldInjector implements Injector {

    final Field field;
    final InternalFactory<?> factory;
    final ExternalContext<?> externalContext;

    public FieldInjector(ContainerImpl container, Field field, String name)
        throws MissingDependencyException {
      this.field = field;
      field.setAccessible(true);

      Key<?> key = Key.newInstance(field.getType(), name);
      factory = container.getFactory(key);
      if (factory == null) {
        throw new MissingDependencyException(
            "No mapping found for dependency " + key + " in " + field + ".");
      }

      this.externalContext = ExternalContext.newInstance(field, key, container);
    }

    public void inject(InternalContext context, Object o) {
      ExternalContext<?> previous = context.getExternalContext();
      context.setExternalContext(externalContext);
      try {
        field.set(o, factory.create(context));
      } catch (IllegalAccessException e) {
        throw new AssertionError(e);
      } finally {
        context.setExternalContext(previous);
      }
    }
  }

  /**
   * Gets parameter injectors.
   *
   * @param member to which the parameters belong
   * @param annotations on the parameters
   * @param parameterTypes parameter types
   * @return injections
   */
  <M extends AccessibleObject & Member> ParameterInjector<?>[]
      getParametersInjectors(M member,
      Annotation[][] annotations, Class[] parameterTypes, String defaultName)
      throws MissingDependencyException {
    List<ParameterInjector<?>> parameterInjectors =
        new ArrayList<ParameterInjector<?>>();

    Iterator<Annotation[]> annotationsIterator =
        Arrays.asList(annotations).iterator();
    for (Class<?> parameterType : parameterTypes) {
      Inject annotation = findInject(annotationsIterator.next());
      String name = annotation == null ? defaultName : annotation.value();
      Key<?> key = Key.newInstance(parameterType, name);
      parameterInjectors.add(createParameterInjector(key, member));
    }

    return toArray(parameterInjectors);
  }

  <T> ParameterInjector<T> createParameterInjector(
      Key<T> key, Member member) throws MissingDependencyException {
    InternalFactory<? extends T> factory = getFactory(key);
    if (factory == null) {
      throw new MissingDependencyException(
          "No mapping found for dependency " + key + " in " + member + ".");
    }

    ExternalContext<T> externalContext =
        ExternalContext.newInstance(member, key, this);
    return new ParameterInjector<T>(externalContext, factory);
  }

  @SuppressWarnings("unchecked")
  private ParameterInjector<?>[] toArray(
      List<ParameterInjector<?>> parameterInjections) {
    return parameterInjections.toArray(
        new ParameterInjector[parameterInjections.size()]);
  }

  /**
   * Finds the {@link Inject} annotation in an array of annotations.
   */
  Inject findInject(Annotation[] annotations) {
    for (Annotation annotation : annotations) {
      if (annotation.annotationType() == Inject.class) {
        return Inject.class.cast(annotation);
      }
    }
    return null;
  }

  static class MethodInjector implements Injector {

    final Method method;
    final ParameterInjector<?>[] parameterInjectors;

    public MethodInjector(ContainerImpl container, Method method, String name)
        throws MissingDependencyException {
      this.method = method;
      method.setAccessible(true);

      Class<?>[] parameterTypes = method.getParameterTypes();
      if (parameterTypes.length == 0) {
        throw new DependencyException(
            method + " has no parameters to inject.");
      }
      parameterInjectors = container.getParametersInjectors(
          method, method.getParameterAnnotations(), parameterTypes, name);
    }

    public void inject(InternalContext context, Object o) {
      try {
        method.invoke(o, getParameters(method, context, parameterInjectors));
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
  }

  Map<Class<?>, ConstructorInjector> constructors =