public class Proxy extends Object implements Serializable
Modifier and Type | Field and Description |
---|---|
protected InvocationHandler |
h
the invocation handler for this proxy instance.
|
Modifier | Constructor and Description |
---|---|
protected |
Proxy(InvocationHandler h)
Constructs a new
Proxy instance from a subclass
(typically, a dynamic proxy class) with the specified value
for its invocation handler. |
Modifier and Type | Method and Description |
---|---|
static Class<?> |
defineProxyClass(Object module,
String name,
byte[] b,
int off,
int len,
ClassLoader loader) |
static InvocationHandler |
getInvocationHandler(Object proxy)
Returns the invocation handler for the specified proxy instance.
|
static Class<?> |
getProxyClass(ClassLoader loader,
Class<?>... interfaces)
Returns the
java.lang.Class object for a proxy class
given a class loader and an array of interfaces. |
static boolean |
isProxyClass(Class<?> cl)
Returns true if and only if the specified class was dynamically
generated to be a proxy class using the
getProxyClass
method or the newProxyInstance method. |
static Object |
newProxyInstance(ClassLoader loader,
Class<?>[] interfaces,
InvocationHandler h)
Returns an instance of a proxy class for the specified interfaces
that dispatches method invocations to the specified invocation
handler.
|
protected InvocationHandler h
protected Proxy(InvocationHandler h)
Proxy
instance from a subclass
(typically, a dynamic proxy class) with the specified value
for its invocation handler.h
- the invocation handler for this proxy instanceNullPointerException
- if the given invocation handler, h
,
is null
.public static Class<?> getProxyClass(ClassLoader loader, Class<?>... interfaces) throws IllegalArgumentException
java.lang.Class
object for a proxy class
given a class loader and an array of interfaces. The proxy class
will be defined by the specified class loader and will implement
all of the supplied interfaces. If any of the given interfaces
is non-public, the proxy class will be non-public. If a proxy class
for the same permutation of interfaces has already been defined by the
class loader, then the existing proxy class will be returned; otherwise,
a proxy class for those interfaces will be generated dynamically
and defined by the class loader.
There are several restrictions on the parameters that may be
passed to Proxy.getProxyClass
:
Class
objects in the
interfaces
array must represent interfaces, not
classes or primitive types.
interfaces
array may
refer to identical Class
objects.
cl
and every interface i
, the following
expression must be true:
Class.forName(i.getName(), false, cl) == i
interfaces
array must not
exceed 65535.
If any of these restrictions are violated,
Proxy.getProxyClass
will throw an
IllegalArgumentException
. If the interfaces
array argument or any of its elements are null
, a
NullPointerException
will be thrown.
Note that the order of the specified proxy interfaces is significant: two requests for a proxy class with the same combination of interfaces but in a different order will result in two distinct proxy classes.
loader
- the class loader to define the proxy classinterfaces
- the list of interfaces for the proxy class
to implementIllegalArgumentException
- if any of the restrictions on the
parameters that may be passed to getProxyClass
are violatedSecurityException
- if a security manager, s, is present
and any of the following conditions is met:
loader
is null
and
the caller's class loader is not null
and the
invocation of s.checkPermission
with
RuntimePermission("getClassLoader")
permission
denies access.intf
,
the caller's class loader is not the same as or an
ancestor of the class loader for intf
and
invocation of s.checkPackageAccess()
denies access to intf
.NullPointerException
- if the interfaces
array
argument or any of its elements are null
public static Object newProxyInstance(ClassLoader loader, Class<?>[] interfaces, InvocationHandler h) throws IllegalArgumentException
Proxy.newProxyInstance
throws
IllegalArgumentException
for the same reasons that
Proxy.getProxyClass
does.
loader
- the class loader to define the proxy classinterfaces
- the list of interfaces for the proxy class
to implementh
- the invocation handler to dispatch method invocations toIllegalArgumentException
- if any of the restrictions on the
parameters that may be passed to getProxyClass
are violatedSecurityException
- if a security manager, s, is present
and any of the following conditions is met:
loader
is null
and
the caller's class loader is not null
and the
invocation of s.checkPermission
with
RuntimePermission("getClassLoader")
permission
denies access;intf
,
the caller's class loader is not the same as or an
ancestor of the class loader for intf
and
invocation of s.checkPackageAccess()
denies access to intf
;s.checkPermission
with
ReflectPermission("newProxyInPackage.{package name}")
permission denies access.NullPointerException
- if the interfaces
array
argument or any of its elements are null
, or
if the invocation handler, h
, is
null
public static boolean isProxyClass(Class<?> cl)
getProxyClass
method or the newProxyInstance
method.
The reliability of this method is important for the ability
to use it to make security decisions, so its implementation should
not just test if the class in question extends Proxy
.
cl
- the class to testtrue
if the class is a proxy class and
false
otherwiseNullPointerException
- if cl
is null
public static InvocationHandler getInvocationHandler(Object proxy) throws IllegalArgumentException
proxy
- the proxy instance to return the invocation handler forIllegalArgumentException
- if the argument is not a
proxy instanceSecurityException
- if a security manager, s, is present
and the caller's class loader is not the same as or an
ancestor of the class loader for the invocation handler
and invocation of s.checkPackageAccess()
denies access to the invocation
handler's class.public static Class<?> defineProxyClass(Object module, String name, byte[] b, int off, int len, ClassLoader loader)
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