--- a/jdk/src/share/classes/java/lang/invoke/MethodHandles.java Tue Sep 03 23:47:27 2013 -0400
+++ b/jdk/src/share/classes/java/lang/invoke/MethodHandles.java Tue Sep 03 21:42:56 2013 -0700
@@ -26,8 +26,6 @@
package java.lang.invoke;
import java.lang.reflect.*;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;
@@ -54,6 +52,7 @@
* </ul>
* <p>
* @author John Rose, JSR 292 EG
+ * @since 1.7
*/
public class MethodHandles {
@@ -97,6 +96,38 @@
}
/**
+ * Performs an unchecked "crack" of a direct method handle.
+ * The result is as if the user had obtained a lookup object capable enough
+ * to crack the target method handle, called
+ * {@link java.lang.invoke.MethodHandles.Lookup#revealDirect Lookup.revealDirect}
+ * on the target to obtain its symbolic reference, and then called
+ * {@link java.lang.invoke.MethodHandleInfo#reflectAs MethodHandleInfo.reflectAs}
+ * to resolve the symbolic reference to a member.
+ * <p>
+ * If there is a security manager, its {@code checkPermission} method
+ * is called with a {@code ReflectPermission("suppressAccessChecks")} permission.
+ * @param <T> the desired type of the result, either {@link Member} or a subtype
+ * @param target a direct method handle to crack into symbolic reference components
+ * @param expected a class object representing the desired result type {@code T}
+ * @return a reference to the method, constructor, or field object
+ * @exception SecurityException if the caller is not privileged to call {@code setAccessible}
+ * @exception NullPointerException if either argument is {@code null}
+ * @exception IllegalArgumentException if the target is not a direct method handle
+ * @exception ClassCastException if the member is not of the expected type
+ * @since 1.8
+ */
+ public static <T extends Member> T
+ reflectAs(Class<T> expected, MethodHandle target) {
+ SecurityManager smgr = System.getSecurityManager();
+ if (smgr != null) smgr.checkPermission(ACCESS_PERMISSION);
+ Lookup lookup = Lookup.IMPL_LOOKUP; // use maximally privileged lookup
+ return lookup.revealDirect(target).reflectAs(expected, lookup);
+ }
+ // Copied from AccessibleObject, as used by Method.setAccessible, etc.:
+ static final private java.security.Permission ACCESS_PERMISSION =
+ new ReflectPermission("suppressAccessChecks");
+
+ /**
* A <em>lookup object</em> is a factory for creating method handles,
* when the creation requires access checking.
* Method handles do not perform
@@ -647,6 +678,7 @@
return invoker(type);
if ("invokeExact".equals(name))
return exactInvoker(type);
+ assert(!MemberName.isMethodHandleInvokeName(name));
return null;
}
@@ -892,6 +924,10 @@
* @throws NullPointerException if the argument is null
*/
public MethodHandle unreflect(Method m) throws IllegalAccessException {
+ if (m.getDeclaringClass() == MethodHandle.class) {
+ MethodHandle mh = unreflectForMH(m);
+ if (mh != null) return mh;
+ }
MemberName method = new MemberName(m);
byte refKind = method.getReferenceKind();
if (refKind == REF_invokeSpecial)
@@ -900,6 +936,12 @@
Lookup lookup = m.isAccessible() ? IMPL_LOOKUP : this;
return lookup.getDirectMethod(refKind, method.getDeclaringClass(), method, findBoundCallerClass(method));
}
+ private MethodHandle unreflectForMH(Method m) {
+ // these names require special lookups because they throw UnsupportedOperationException
+ if (MemberName.isMethodHandleInvokeName(m.getName()))
+ return MethodHandleImpl.fakeMethodHandleInvoke(new MemberName(m));
+ return null;
+ }
/**
* Produces a method handle for a reflected method.
@@ -1004,6 +1046,46 @@
return unreflectField(f, true);
}
+ /**
+ * Cracks a direct method handle created by this lookup object or a similar one.
+ * Security and access checks are performed to ensure that this lookup object
+ * is capable of reproducing the target method handle.
+ * This means that the cracking may fail if target is a direct method handle
+ * but was created by an unrelated lookup object.
+ * @param target a direct method handle to crack into symbolic reference components
+ * @return a symbolic reference which can be used to reconstruct this method handle from this lookup object
+ * @exception SecurityException if a security manager is present and it
+ * <a href="MethodHandles.Lookup.html#secmgr">refuses access</a>
+ * @throws IllegalArgumentException if the target is not a direct method handle or if access checking fails
+ * @exception NullPointerException if the target is {@code null}
+ * @since 1.8
+ */
+ public MethodHandleInfo revealDirect(MethodHandle target) {
+ MemberName member = target.internalMemberName();
+ if (member == null || (!member.isResolved() && !member.isMethodHandleInvoke()))
+ throw newIllegalArgumentException("not a direct method handle");
+ Class<?> defc = member.getDeclaringClass();
+ byte refKind = member.getReferenceKind();
+ assert(MethodHandleNatives.refKindIsValid(refKind));
+ if (refKind == REF_invokeSpecial && !target.isInvokeSpecial())
+ // Devirtualized method invocation is usually formally virtual.
+ // To avoid creating extra MemberName objects for this common case,
+ // we encode this extra degree of freedom using MH.isInvokeSpecial.
+ refKind = REF_invokeVirtual;
+ if (refKind == REF_invokeVirtual && defc.isInterface())
+ // Symbolic reference is through interface but resolves to Object method (toString, etc.)
+ refKind = REF_invokeInterface;
+ // Check SM permissions and member access before cracking.
+ try {
+ checkSecurityManager(defc, member);
+ checkAccess(refKind, defc, member);
+ } catch (IllegalAccessException ex) {
+ throw new IllegalArgumentException(ex);
+ }
+ // Produce the handle to the results.
+ return new InfoFromMemberName(this, member, refKind);
+ }
+
/// Helper methods, all package-private.
MemberName resolveOrFail(byte refKind, Class<?> refc, String name, Class<?> type) throws NoSuchFieldException, IllegalAccessException {
@@ -1201,12 +1283,12 @@
private MethodHandle getDirectMethodCommon(byte refKind, Class<?> refc, MemberName method,
boolean doRestrict, Class<?> callerClass) throws IllegalAccessException {
checkMethod(refKind, refc, method);
- if (method.isMethodHandleInvoke())
- return fakeMethodHandleInvoke(method);
+ assert(!method.isMethodHandleInvoke());
Class<?> refcAsSuper;
if (refKind == REF_invokeSpecial &&
refc != lookupClass() &&
+ !refc.isInterface() &&
refc != (refcAsSuper = lookupClass().getSuperclass()) &&
refc.isAssignableFrom(lookupClass())) {
assert(!method.getName().equals("<init>")); // not this code path
@@ -1234,9 +1316,6 @@
mh = restrictReceiver(method, mh, lookupClass());
return mh;
}
- private MethodHandle fakeMethodHandleInvoke(MemberName method) {
- return throwException(method.getReturnType(), UnsupportedOperationException.class);
- }
private MethodHandle maybeBindCaller(MemberName method, MethodHandle mh,
Class<?> callerClass)
throws IllegalAccessException {