Package net.bytebuddy.utility.dispatcher

Class JavaDispatcher<T>

java.lang.Object

net.bytebuddy.utility.dispatcher.JavaDispatcher<T>

Type Parameters:

T - The resolved type.

All Implemented Interfaces:

PrivilegedAction<T>

@Enhance
public class JavaDispatcher<T>
extends Object
implements PrivilegedAction<T>

A dispatcher for creating a proxy that invokes methods of a type that is possibly unknown on the current VM. Dispatchers do not use any of Byte Buddy's regular infrastructure, to avoid bootstrapping issues as these dispatchers are used by Byte Buddy itself.

By default, this dispatcher uses the Java Proxy for creating dispatchers. By setting net.bytebuddy.generate to true, Byte Buddy can generate proxies manually as byte code to mostly avoid reflection and boxing of arguments as arrays.

If a security manager is active, the net.bytebuddy.createJavaDispatcher runtime permission is required. Any dispatching will be executed from a separate class loader and an unnamed module but with the ProtectionDomain of the JavaDispatcher class. It is not permitted to invoke methods of the java.security.AccessController class or to resolve a java.lang.invoke.MethodHandle$Lookup.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static @interface	JavaDispatcher.Container	Indicates that the method is supposed to return an array of the proxied type.
static @interface	JavaDispatcher.Defaults	Indicates that a method is supposed to return a default value if a method or type could not be resolved.
private static class	JavaDispatcher.DirectInvoker	An Invoker that uses Byte Buddy's invocation context to use if dynamic class loading is not supported, for example on Android, and that do not use secured contexts, where this security measure is obsolete to begin with.
protected static interface	JavaDispatcher.Dispatcher	A dispatcher for handling a proxied method.
protected static class	JavaDispatcher.DynamicClassLoader	A class loader for loading synthetic classes for implementing a JavaDispatcher.
static @interface	JavaDispatcher.Instance	Indicates that a method is supposed to perform an instance check.
private static class	JavaDispatcher.InvokerCreationAction	A privileged action for creating an Invoker.
static @interface	JavaDispatcher.IsConstructor	Indicates that a proxied method is a constructor.
static @interface	JavaDispatcher.IsStatic	Indicates that a proxied method is static.
static @interface	JavaDispatcher.Proxied	Indicates a proxied type's name.
protected static class	JavaDispatcher.ProxiedInvocationHandler	An invocation handler that invokes given dispatchers.

Field Summary

Fields

Modifier and Type	Field	Description
private final ClassLoader	classLoader	The class loader to resolve the proxied type from or null if the bootstrap loader should be used.
private final boolean	generate	true if a proxy class should be manually generated.
private static final boolean	GENERATE	If true, dispatcher classes will be generated natively and not by using a Proxy.
static final String	GENERATE_PROPERTY	A property to determine, that if true, dispatcher classes will be generated natively and not by using a Proxy.
private static final Invoker	INVOKER	Contains an invoker that makes sure that reflective dispatchers make invocations from an isolated ClassLoader and not from within Byte Buddy's context.
private final Class<T>	proxy	The proxy type.
private static final JavaDispatcher.DynamicClassLoader.Resolver	RESOLVER	A resolver to assure that a type's package and module are exported to the created class loader.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	JavaDispatcher(Class<T> proxy, ClassLoader classLoader, boolean generate)	Creates a new dispatcher.

Method Summary

Modifier and Type	Method	Description
private static <T> T	doPrivileged(PrivilegedAction<T> action)	A proxy for java.security.AccessController#doPrivileged that is activated if available.
static <T> PrivilegedAction<T>	of(Class<T> type)	Resolves an action for creating a dispatcher for the provided type where the proxied type is resolved from the bootstrap loader.
protected static <T> PrivilegedAction<T>	of(Class<T> type, ClassLoader classLoader)	Resolves an action for creating a dispatcher for the provided type.
protected static <T> PrivilegedAction<T>	of(Class<T> type, ClassLoader classLoader, boolean generate)	Resolves an action for creating a dispatcher for the provided type.
T	run()

Methods inherited from class java.lang.Object

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

Field Details

GENERATE_PROPERTY

public static final String GENERATE_PROPERTY

A property to determine, that if true, dispatcher classes will be generated natively and not by using a Proxy.

See Also:

• Constant Field Values

GENERATE

private static final boolean GENERATE

If true, dispatcher classes will be generated natively and not by using a Proxy.

RESOLVER

private static final JavaDispatcher.DynamicClassLoader.Resolver RESOLVER

A resolver to assure that a type's package and module are exported to the created class loader. This should normally always be the case, but if another library is shading Byte Buddy or otherwise manipulates the module graph, this might become necessary.

INVOKER

private static final Invoker INVOKER

Contains an invoker that makes sure that reflective dispatchers make invocations from an isolated ClassLoader and not from within Byte Buddy's context. This way, no privilege context can be leaked by accident.

proxy

private final Class<T> proxy

The proxy type.

classLoader

@MaybeNull
@ValueHandling(REVERSE_NULLABILITY)
private final ClassLoader classLoader

The class loader to resolve the proxied type from or null if the bootstrap loader should be used.

generate

private final boolean generate

true if a proxy class should be manually generated.

Constructor Details

JavaDispatcher

protected JavaDispatcher(Class<T> proxy,
 @MaybeNull
 ClassLoader classLoader,
 boolean generate)

Creates a new dispatcher.

Parameters:

proxy - The proxy type.

classLoader - The class loader to resolve the proxied type from or null if the bootstrap loader should be used.

generate - true if a proxy class should be manually generated.

Method Details

doPrivileged

@Enhance
private static <T> T doPrivileged(PrivilegedAction<T> action)

A proxy for java.security.AccessController#doPrivileged that is activated if available.

Type Parameters:

T - The type of the action's resolved value.

Parameters:

action - The action to execute from a privileged context.

Returns:

The action's resolved value.

of

public static <T> PrivilegedAction<T> of(Class<T> type)

Resolves an action for creating a dispatcher for the provided type where the proxied type is resolved from the bootstrap loader.

Type Parameters:

T - The resolved type.

Parameters:

type - The type for which a dispatcher should be resolved.

Returns:

An action for creating an appropriate dispatcher.

of

protected static <T> PrivilegedAction<T> of(Class<T> type,
 @MaybeNull
 ClassLoader classLoader)

Resolves an action for creating a dispatcher for the provided type.

Type Parameters:

T - The resolved type.

Parameters:

type - The type for which a dispatcher should be resolved.

classLoader - The class loader to resolve the proxied type from.

Returns:

An action for creating an appropriate dispatcher.

of

protected static <T> PrivilegedAction<T> of(Class<T> type,
 @MaybeNull
 ClassLoader classLoader,
 boolean generate)

Resolves an action for creating a dispatcher for the provided type.

Type Parameters:

T - The resolved type.

Parameters:

type - The type for which a dispatcher should be resolved.

classLoader - The class loader to resolve the proxied type from.

generate - true if a proxy class should be manually generated.

Returns:

An action for creating an appropriate dispatcher.

run

public T run()

Specified by:

run in interface PrivilegedAction<T>