filestubhandler.java

JdbcProxy 可以理解为 JDBC 代理

package nl.griffelservices.proxy.stub;

import java.lang.reflect.Method;

import nl.griffelservices.proxy.Handler;
import nl.griffelservices.proxy.Proxy;

/**
 * This handler is meant to provide stub responses for the calls to the proxied interfaces.
 * The actual stub responses are provided by a {@link Stub} class.
 * This driver uses the {@link ProxyObject} as the proxy data.
 * Note that this proxy data already contains pre-configured stub responses for a set of requests.
 * This means that for these request, the {@link Stub} does not need to be invoked.
 * 
 * @author [e-mail]
 */
public class FileStubHandler implements Handler
{
  /** The object that provides the actual stub responses */
  private FileStub stub;
  
  /**
   * Constructs a StubHandler object.
   * 
   * @param stub the object that provides the actual stub responses
   */
  public FileStubHandler(FileStub stub)
  {
    this.stub = stub;
  }
  
  public void init(Class proxyClass, Object proxyObject)
  {
    // Do nothing;
  }

  public Object invoke(Proxy proxy, Method method, Object[] parameters) throws Exception
  {
    if (method.getParameterTypes().length != parameters.length)
    {
      throw new IllegalArgumentException("Number of parameters " + parameters.length + " does not match method " + method);
    }
    ProxyObject proxyObject = (ProxyObject)proxy.getProxyObject();
    
    // first see whether a response for this call has already been loaded in the proxy object
    for (int i = 0; i < proxyObject.getRequestResponseCount(); i++)
    {
      if (proxyObject.getRequestResponse(i).getRequest().matches(proxyObject.getProxyId(), proxyObject.getProxyStatus(), method, parameters))
      {
        return invoke(proxy, method, proxyObject.getRequestResponse(i).getResponse());
      }
    }
    
    // No response was found in the proxy object, so ask the stub
    Request.EqualityParameter equalityParameters[] = new Request.EqualityParameter[parameters.length];
    for (int i = 0; i < parameters.length; i++)
    {
      equalityParameters[i] = new Request.EqualityParameter(parameters[i].toString());
    }
    Request request = new Request(proxyObject.getProxyId(),
                                  new Request.EqualityParameter(proxyObject.getProxyStatus()),
                                  method,
                                  equalityParameters);
    return invoke(proxy, method, stub.invoke(request));
  }
  
  /**
   * Sets the new proxy status and returns the proxy class for the return value.
   * 
   * @param proxy the proxy class whose method is called
   * @param method the method that is called
   * @param response the response for the method call
   * @return the proxy class for the return value
   */
  private Object invoke(Proxy proxy, Method method, Response response)
  {
    ((ProxyObject)proxy.getProxyObject()).setProxyStatus(response.getNewStatus());
    if (response.getReturnValue() instanceof ProxyObject)
    {
      ProxyObject returnValue = (ProxyObject)((ProxyObject)response.getReturnValue()).clone();
      return proxy.getReturnValueProxy(returnValue.getProxyClass(), this, returnValue);
    }
    else
    {
      return proxy.getReturnValueProxy(method.getReturnType(), this, response.getReturnValue());
    }
  }
}