Package org.perfectable.introspection.proxy

Interface ProxyService

All Known Implementing Classes:

JavassistProxyService, JdkProxyService

@Immutable
public interface ProxyService

Method of producing proxies.

There are multiple ways of creating proxy in Java, from simple Proxy, through support frameworks like javassist, to class generation libraries like cglib or bytebuddy. This class creates universal facade to potentially all these methods.

Different frameworks supports different proxying features, for example, javassist can create proxy classes that extend specific non-final class, not only that implement specific interfaces. These features are represented by ProxyService.Feature and can be tested for support (using supportsAllFeatures(org.perfectable.introspection.proxy.ProxyService.Feature...) or supportsFeature(org.perfectable.introspection.proxy.ProxyService.Feature)).

Interface implementation can be registered to be used with ServiceLoader, and should be obtained using INSTANCES.

This interface can be implemented externally, and registered with Service Loader to be usable in ProxyBuilder.

See Also:

ProxyBuilder

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	ProxyService.Container	Container that manages service-loaded instances of ProxyService.
static class	ProxyService.Feature	Features that service can support.
static class	ProxyService.UnsupportedFeatureException	Thrown when factory cannot create a builder with requested features.

Field Summary

Fields

Modifier and Type	Field	Description
static ProxyService.Container	INSTANCES	Container managing all instances registered with ServiceLoader.

Method Summary

Modifier and Type	Method	Description
<I> I	instantiate(ClassLoader classLoader, Class<?> baseClass, List<? extends Class<?>> interfaces, InvocationHandler<? super MethodInvocation<I>> handler)	Creates proxy instance.
default boolean	supportsAllFeatures(ProxyService.Feature... features)	If the concrete service supports all of specified features.
boolean	supportsFeature(ProxyService.Feature feature)	If the concrete service supports specified feature.

Field Detail

INSTANCES

static final ProxyService.Container INSTANCES

Container managing all instances registered with ServiceLoader.

Method Detail

supportsFeature

boolean supportsFeature(ProxyService.Feature feature)

If the concrete service supports specified feature.

Parameters:

feature - feature to test

Returns:

if service supports feature

supportsAllFeatures

default boolean supportsAllFeatures(ProxyService.Feature... features)

If the concrete service supports all of specified features.

Parameters:

features - feature set to test

Returns:

if service supports features

instantiate

<I> I instantiate(ClassLoader classLoader,
                  Class<?> baseClass,
                  List<? extends Class<?>> interfaces,
                  InvocationHandler<? super MethodInvocation<I>> handler)
           throws ProxyService.UnsupportedFeatureException

Creates proxy instance.

This method either creates new proxy class, or reuses one that matches. This proxy class extends baseClass and implements interfaces, and is created in classLoader. After creating this class, its object is instantiated. The object will delegate every call that it receives to specified InvocationHandler. The only exception is Object.finalize(), which must be ignored.

This method assumes that the arguments were correctly prepared:

• baseClass is not final
• baseClass is actually a class (not an interface)
• baseClass and each element of interfaces has classloader exactly classLoader
• Each element in interfaces is an interface (not a class)

Type Parameters:

I - type of proxy

Parameters:

classLoader - classloader used to create proxy class

baseClass - proxy superclass, cannot be final, must be a class

interfaces - additional interfaces that proxy class should implement

handler - invocation handler to pass method execution for this proxy instance

Returns:

proxy instance

Throws:

ProxyService.UnsupportedFeatureException - when this service cannot create proxy with requested parameters, because it doesn't support some feature required to do so