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spring ide_2.3.0 » org » springframework » aop » framework » ReflectiveMethodInvocation.java
/*
 * Copyright 2002-2007 the original author or authors.
 *
 * 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 org.springframework.aop.framework;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.aop.ProxyMethodInvocation;
import org.springframework.aop.support.AopUtils;

/**
 * Spring's implementation of the AOP Alliance
 * {@link org.aopalliance.intercept.MethodInvocation} interface,
 * implementing the extended
 * {@link org.springframework.aop.ProxyMethodInvocation} interface.
 *
 * <p>Invokes the target object using reflection. Subclasses can override the
 * {@link #invokeJoinpoint()} method to change this behavior, so this is also
 * a useful base class for more specialized MethodInvocation implementations.
 *
 * <p>It is possible to clone an invocation, to invoke {@link #proceed()}
 * repeatedly (once per clone), using the {@link #invocableClone()} method.
 * It is also possible to attach custom attributes to the invocation,
 * using the {@link #setUserAttribute} / {@link #getUserAttribute} methods.
 *
 * <p><b>NOTE:</b> This class is considered internal and should not be
 * directly accessed. The sole reason for it being public is compatibility
 * with existing framework integrations (e.g. Pitchfork). For any other
 * purposes, use the {@link ProxyMethodInvocation} interface instead.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Adrian Colyer
 * @see #invokeJoinpoint
 * @see #proceed
 * @see #invocableClone
 * @see #setUserAttribute
 * @see #getUserAttribute
 */
public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable {

  protected final Object proxy;

  protected final Object target;

  protected final Method method;

  protected Object[] arguments;

  private final Class targetClass;

  /**
   * Lazily initialized map of user-specific attributes for this invocation.
   */
  private Map userAttributes;

  /**
   * List of MethodInterceptor and InterceptorAndDynamicMethodMatcher
   * that need dynamic checks.
   */
  protected final List interceptorsAndDynamicMethodMatchers;

  /**
   * Index from 0 of the current interceptor we're invoking.
   * -1 until we invoke: then the current interceptor.
   */
  private int currentInterceptorIndex = -1;


  /**
   * Construct a new ReflectiveMethodInvocation with the given arguments.
   * @param proxy the proxy object that the invocation was made on
   * @param target the target object to invoke
   * @param method the method to invoke
   * @param arguments the arguments to invoke the method with
   * @param targetClass the target class, for MethodMatcher invocations
   * @param interceptorsAndDynamicMethodMatchers interceptors that should be applied,
   * along with any InterceptorAndDynamicMethodMatchers that need evaluation at runtime.
   * MethodMatchers included in this struct must already have been found to have matched
   * as far as was possibly statically. Passing an array might be about 10% faster,
   * but would complicate the code. And it would work only for static pointcuts.
   */
  protected ReflectiveMethodInvocation(
      Object proxy, Object target, Method method, Object[] arguments,
      Class targetClass, List interceptorsAndDynamicMethodMatchers) {

    this.proxy = proxy;
    this.target = target;
    this.targetClass = targetClass;
    this.method = method;
    this.arguments = arguments;
    this.interceptorsAndDynamicMethodMatchers = interceptorsAndDynamicMethodMatchers;
  }


  public final Object getProxy() {
    return this.proxy;
  }

  public final Object getThis() {
    return this.target;
  }

  public final AccessibleObject getStaticPart() {
    return this.method;
  }

  /**
   * Return the method invoked on the proxied interface.
   * May or may not correspond with a method invoked on an underlying
   * implementation of that interface.
   */
  public final Method getMethod() {
    return this.method;
  }

  public final Object[] getArguments() {
    return (this.arguments != null ? this.arguments : new Object[0]);
  }

  public void setArguments(Object[] arguments) {
    this.arguments = arguments;
  }


  public Object proceed() throws Throwable {
    //  We start with an index of -1 and increment early.
    if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
      return invokeJoinpoint();
    }

    Object interceptorOrInterceptionAdvice =
        this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
    if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
      // Evaluate dynamic method matcher here: static part will already have
      // been evaluated and found to match.
      InterceptorAndDynamicMethodMatcher dm =
          (InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
      if (dm.methodMatcher.matches(this.method, this.targetClass, this.arguments)) {
        return dm.interceptor.invoke(this);
      }
      else {
        // Dynamic matching failed.
        // Skip this interceptor and invoke the next in the chain.
        return proceed();
      }
    }
    else {
      // It's an interceptor, so we just invoke it: The pointcut will have
      // been evaluated statically before this object was constructed.
      return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
    }
  }

  /**
   * Invoke the joinpoint using reflection.
   * Subclasses can override this to use custom invocation.
   * @return the return value of the joinpoint
   * @throws Throwable if invoking the joinpoint resulted in an exception
   */
  protected Object invokeJoinpoint() throws Throwable {
    return AopUtils.invokeJoinpointUsingReflection(this.target, this.method, this.arguments);
  }


  /**
   * This implementation returns a shallow copy of this invocation object,
   * including an independent copy of the original arguments array.
   * <p>We want a shallow copy in this case: We want to use the same interceptor
   * chain and other object references, but we want an independent value for the
   * current interceptor index.
   * @see java.lang.Object#clone()
   */
  public MethodInvocation invocableClone() {
    Object[] cloneArguments = null;
    if (this.arguments != null) {
      // Build an independent copy of the arguments array.
      cloneArguments = new Object[this.arguments.length];
      System.arraycopy(this.arguments, 0, cloneArguments, 0, this.arguments.length);
    }
    return invocableClone(cloneArguments);
  }

  /**
   * This implementation returns a shallow copy of this invocation object,
   * using the given arguments array for the clone.
   * <p>We want a shallow copy in this case: We want to use the same interceptor
   * chain and other object references, but we want an independent value for the
   * current interceptor index.
   * @see java.lang.Object#clone()
   */
  public MethodInvocation invocableClone(Object[] arguments) {
    // Force initialization of the user attributes Map,
    // for having a shared Map reference in the clone.
    if (this.userAttributes == null) {
      this.userAttributes = new HashMap();
    }

    // Create the MethodInvocation clone.
    try {
      ReflectiveMethodInvocation clone = (ReflectiveMethodInvocation) clone();
      clone.arguments = arguments;
      return clone;
    }
    catch (CloneNotSupportedException ex) {
      throw new IllegalStateException(
          "Should be able to clone object of type [" + getClass() + "]: " + ex);
    }
  }


  public void setUserAttribute(String key, Object value) {
    if (value != null) {
      if (this.userAttributes == null) {
        this.userAttributes = new HashMap();
      }
      this.userAttributes.put(key, value);
    }
    else {
      if (this.userAttributes != null) {
        this.userAttributes.remove(key);
      }
    }
  }

  public Object getUserAttribute(String key) {
    return (this.userAttributes != null ? this.userAttributes.get(key) : null);
  }

  /**
   * Return user attributes associated with this invocation.
   * This method provides an invocation-bound alternative to a ThreadLocal.
   * <p>This map is initialized lazily and is not used in the AOP framework itself.
   * @return any user attributes associated with this invocation
   * (never <code>null</code>)
   */
  public Map getUserAttributes() {
    if (this.userAttributes == null) {
      this.userAttributes = new HashMap();
    }
    return this.userAttributes;
  }


  public String toString() {
    // Don't do toString on target, it may be proxied.
    StringBuffer sb = new StringBuffer("ReflectiveMethodInvocation: ");
    sb.append(this.method).append("; ");
    if (this.target == null) {
      sb.append("target is null");
    }
    else {
      sb.append("target is of class [").append(this.target.getClass().getName()).append(']');
    }
    return sb.toString();
  }

}
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