com.javax0.djcproxy

Class ProxyFactory<ClassToBeProxied>

java.lang.Object

com.javax0.djcproxy.ProxyFactory<ClassToBeProxied>

Type Parameters:

ClassToBeProxied -

public class ProxyFactory<ClassToBeProxied>
extends Object

Factory to create new proxy object. To create a proxy object you need a factory that is able to create new class that proxies the original object and also can compile the generated Java source and load the compiled class.

Usually there are many object created for the same class and for this reason a factory keeps track of the already generated classes and when a class can be reused it will not be generated again, but the already loaded class will be used.

Author:

Peter Verhas

Constructor Summary

Constructors

Constructor and Description
ProxyFactory()

Method Summary

Methods

Modifier and Type	Method and Description
ClassToBeProxied	create(ClassToBeProxied originalObject, MethodInterceptor interceptor) Create a new proxy object.
Class<?>	createClass(Class<?> originalClass) Create a new proxy class that is capable proxying an object that is an instance of the class.
String	getCompilerErrorOutput()
String	getGeneratedClassName() Get the name of the class that was generated last time.
String	getGeneratedSource() Get the source code that was generated by the factory last time.
ProxySetter	instantiateProxy(Class<?> proxyClass) Instantiate a proxy object from a proxyClass.
void	setCallbackFilter(CallbackFilter callbackFilter) Set a valid callback filter.
void	setClassLoader(ClassLoader classLoader) By the default the classloader used to load the original class is used to load the proxy class.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ProxyFactory

public ProxyFactory()

Method Detail

setCallbackFilter

public void setCallbackFilter(CallbackFilter callbackFilter)

Set a valid callback filter.

Parameters:

callbackFilter - is the callback filter object and can not be null. When null argument is passed IllegalArgumentException is thrown.

setClassLoader

public void setClassLoader(ClassLoader classLoader)

By the default the classloader used to load the original class is used to load the proxy class. In some cases this does not work, when the original class loader can not load the class ProxySetter and/or MethodInterceptor classes. This is typically in the weird case when the you want to proxy some of the system classes. In that case you can set the classloader calling this method. For example you can

 ProxyFactory<Object> factory = new ProxyFactory<>();
 factory.setClassLoader(this.getClass().getClassLoader());
 

Parameters:

classLoader -

getGeneratedSource

public String getGeneratedSource()

Get the source code that was generated by the factory last time. Since a factory can be used to generate more than one source class there is no guarantee that the returned source is the source of the last object returned. This method is to help debugging and learning how the proxy factory works. To ensure that the source is the one the caller is interested in create a new ProxyFactory and use it only once to generate a proxy object.

Returns:

getGeneratedClassName

public String getGeneratedClassName()

Get the name of the class that was generated last time. The same caveats hold as in the method getGeneratedSource().

Returns:

getCompilerErrorOutput

public String getCompilerErrorOutput()

create

public ClassToBeProxied create(ClassToBeProxied originalObject,
                      MethodInterceptor interceptor)
                        throws Exception

Create a new proxy object.

Parameters:

originalObject - the object to be proxied

Returns:

the new proxy object

Throws:

Exception - when the proxy can not be created. This can be for several reasons. Identified reasons:

• The original object is an instance of a final class
• The original object is an inner class that is private and thus can not be extended.

createClass

public Class<?> createClass(Class<?> originalClass)
                     throws Exception

Create a new proxy class that is capable proxying an object that is an instance of the class.

Parameters:

originalObject -

interceptor -

Returns:

Throws:

Exception

instantiateProxy

public ProxySetter instantiateProxy(Class<?> proxyClass)
                             throws Exception

Instantiate a proxy object from a proxyClass. Note that the created object is not initialized properly.

Parameters:

proxyClass -

Returns:

Throws:

Exception