/*
*
* This software is granted under the terms of the Common Public License,
* CPL, which may be found at the following URL:
* http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
*
* Copyright(c) 2003-2005 by the authors indicated in the @author tags.
* All Rights are Reserved by the various authors.
*
########## DO NOT EDIT ABOVE THIS LINE ########## */
/**
* Demonstrates the use of interface based proxies.
*
* @author <a href=mailto:[email protected]>Robert Simmons jr. (kraythe)</a>
* @version $Revision: 1.2 $
*/ public class DemoInterfaceProxy {
/**
* Use a proxy and check the count.
*/ public static final void checkCount() {
SomeClass proxy = SomeClassFactory.getSomeClassProxy();
proxy.someMethod();
proxy.someOtherMethod("Our Proxy works!"); if (proxy instanceof SomeClassCountingProxy) {
System.out.println(((SomeClassCountingProxy)proxy).getInvocationCount());
}
}
/**
* Run the demonstration.
*
* @param args Command Line Arguments (ignored).
*/ public static final void main(final String[] args) {
SomeClass proxy = SomeClassFactory.getSomeClassProxy();
proxy.someMethod();
proxy.someOtherMethod("Our Proxy works!");
}
} class SomeClassFactory {
/**
* Gets a counting proxy to an object that is constructed with the user name.
*
* @return The proxy to the implementation.
*/ public static final SomeClassCountingProxy getCountingProxy() {
SomeClassImpl impl = new SomeClassImpl(System.getProperty("user.name")); return new SomeClassCountingProxy(impl);
}
/**
* Gets proxy to depending upon debug status in Log4J.
*
* @return The proxy to the implementation.
*/ public static final SomeClass getDynamicSomeClassProxy() {
SomeClassImpl impl = new SomeClassImpl(System.getProperty("user.name"));
InvocationHandler handler = new MethodCountingHandler(impl); Class[] interfaces = new Class[] { SomeClass.class };
ClassLoader loader = SomeClassFactory.class.getClassLoader();
SomeClass proxy = (SomeClass) Proxy.newProxyInstance(loader, interfaces, handler); return proxy;
}
/**
* Gets a proxy to an object that is constructed with the user name.
*
* @return The proxy to the implementation.
*/ public static final SomeClassProxy getProxy() {
SomeClassImpl impl = new SomeClassImpl(System.getProperty("user.name")); return new SomeClassProxy(impl);
}
/**
* Gets proxy to depending upon debug status in Log4J.
*
* @return The proxy to the implementation.
*/ public static final SomeClass getSomeClassProxy() {
SomeClassImpl impl = new SomeClassImpl(System.getProperty("user.name")); if (true) { return new SomeClassCountingProxy(impl);
} else { return new SomeClassProxy(impl);
}
}
} class SomeClassCountingProxy implements SomeClass {
/** The implementation object for this proxy. */ private final SomeClassImpl impl;
/** Holds the invocation count. */ private int invocationCount = 0;
/**
* Creates a new SomeClassProxy object.
*
* @param impl The implementation object for this proxy.
*/ public SomeClassCountingProxy(final SomeClassImpl impl) { this.impl = impl;
}
/**
* Gets the value of the property invocationCount.
*
* @return The current value of invocationCount
*/ public int getInvocationCount() { return invocationCount;
}
/**
* @see java2s.hcj.proxies.SomeClass#someOtherMethod(java.lang.String)
*/ public void someOtherMethod(String text) { this.invocationCount++; this.impl.someOtherMethod(text);
}
} class SomeClassImpl implements SomeClass {
/** Holds the user name. */ private String userName;
/**
* Creates a new SomeClass object.
*
* @param userName
* The user name to use.
*/ public SomeClassImpl(final String userName) { this.userName = userName;
}
class SomeClassProxy implements SomeClass {
/** The impl object for this proxy. */ private final SomeClassImpl impl;
/**
* Creates a new SomeClassProxy object.
*
* @param impl
* The implementation object for this proxy.
*/ public SomeClassProxy(final SomeClassImpl impl) { this.impl = impl;
}
interface SomeClass {
/**
* Print out the user name.
*/ public abstract void someMethod();
/**
* Print out the string given to us.
*
* @param text
* The string to print.
*/ public abstract void someOtherMethod(final String text);
}
/**
* An invocation handler that counts the number of calls for all methods in the
* target class.
*
* @author <a href=mailto:[email protected]>Robert Simmons jr. (kraythe)</a>
* @version $Revision: 1.2 $
*
* @see java.lang.reflect.InvocationHandler
*/ class MethodCountingHandler implements InvocationHandler {
/** The implementation object for this proxy. */ private final Object impl;
/** Holds the invocation count. */ private int invocationCount = 0;
/**
* Creates a new MethodCOuntingHandler object.
*
* @param impl
*/ public MethodCountingHandler(final Object impl) { this.impl = impl;
}
/**
* Gets the value of the property invocationCount.
*
* @return The current value of invocationCount
*/ public int getInvocationCount() { return invocationCount;
}