jdk/src/share/classes/java/lang/reflect/AccessibleObject.java
changeset 2 90ce3da70b43
child 51 6fe31bc95bbc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/lang/reflect/AccessibleObject.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,202 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.lang.reflect;
+
+import java.security.AccessController;
+import sun.reflect.ReflectionFactory;
+import java.lang.annotation.Annotation;
+
+/**
+ * The AccessibleObject class is the base class for Field, Method and
+ * Constructor objects.  It provides the ability to flag a reflected
+ * object as suppressing default Java language access control checks
+ * when it is used.  The access checks--for public, default (package)
+ * access, protected, and private members--are performed when Fields,
+ * Methods or Constructors are used to set or get fields, to invoke
+ * methods, or to create and initialize new instances of classes,
+ * respectively.
+ *
+ * <p>Setting the {@code accessible} flag in a reflected object
+ * permits sophisticated applications with sufficient privilege, such
+ * as Java Object Serialization or other persistence mechanisms, to
+ * manipulate objects in a manner that would normally be prohibited.
+ *
+ * @see Field
+ * @see Method
+ * @see Constructor
+ * @see ReflectPermission
+ *
+ * @since 1.2
+ */
+public class AccessibleObject implements AnnotatedElement {
+
+    /**
+     * The Permission object that is used to check whether a client
+     * has sufficient privilege to defeat Java language access
+     * control checks.
+     */
+    static final private java.security.Permission ACCESS_PERMISSION =
+        new ReflectPermission("suppressAccessChecks");
+
+    /**
+     * Convenience method to set the {@code accessible} flag for an
+     * array of objects with a single security check (for efficiency).
+     *
+     * <p>First, if there is a security manager, its
+     * {@code checkPermission} method is called with a
+     * {@code ReflectPermission("suppressAccessChecks")} permission.
+     *
+     * <p>A {@code SecurityException} is raised if {@code flag} is
+     * {@code true} but accessibility of any of the elements of the input
+     * {@code array} may not be changed (for example, if the element
+     * object is a {@link Constructor} object for the class {@link
+     * java.lang.Class}).  In the event of such a SecurityException, the
+     * accessibility of objects is set to {@code flag} for array elements
+     * upto (and excluding) the element for which the exception occurred; the
+     * accessibility of elements beyond (and including) the element for which
+     * the exception occurred is unchanged.
+     *
+     * @param array the array of AccessibleObjects
+     * @param flag  the new value for the {@code accessible} flag
+     *              in each object
+     * @throws SecurityException if the request is denied.
+     * @see SecurityManager#checkPermission
+     * @see java.lang.RuntimePermission
+     */
+    public static void setAccessible(AccessibleObject[] array, boolean flag)
+        throws SecurityException {
+        SecurityManager sm = System.getSecurityManager();
+        if (sm != null) sm.checkPermission(ACCESS_PERMISSION);
+        for (int i = 0; i < array.length; i++) {
+            setAccessible0(array[i], flag);
+        }
+    }
+
+    /**
+     * Set the {@code accessible} flag for this object to
+     * the indicated boolean value.  A value of {@code true} indicates that
+     * the reflected object should suppress Java language access
+     * checking when it is used.  A value of {@code false} indicates
+     * that the reflected object should enforce Java language access checks.
+     *
+     * <p>First, if there is a security manager, its
+     * {@code checkPermission} method is called with a
+     * {@code ReflectPermission("suppressAccessChecks")} permission.
+     *
+     * <p>A {@code SecurityException} is raised if {@code flag} is
+     * {@code true} but accessibility of this object may not be changed
+     * (for example, if this element object is a {@link Constructor} object for
+     * the class {@link java.lang.Class}).
+     *
+     * <p>A {@code SecurityException} is raised if this object is a {@link
+     * java.lang.reflect.Constructor} object for the class
+     * {@code java.lang.Class}, and {@code flag} is true.
+     *
+     * @param flag the new value for the {@code accessible} flag
+     * @throws SecurityException if the request is denied.
+     * @see SecurityManager#checkPermission
+     * @see java.lang.RuntimePermission
+     */
+    public void setAccessible(boolean flag) throws SecurityException {
+        SecurityManager sm = System.getSecurityManager();
+        if (sm != null) sm.checkPermission(ACCESS_PERMISSION);
+        setAccessible0(this, flag);
+    }
+
+    /* Check that you aren't exposing java.lang.Class.<init>. */
+    private static void setAccessible0(AccessibleObject obj, boolean flag)
+        throws SecurityException
+    {
+        if (obj instanceof Constructor && flag == true) {
+            Constructor c = (Constructor)obj;
+            if (c.getDeclaringClass() == Class.class) {
+                throw new SecurityException("Can not make a java.lang.Class" +
+                                            " constructor accessible");
+            }
+        }
+        obj.override = flag;
+    }
+
+    /**
+     * Get the value of the {@code accessible} flag for this object.
+     *
+     * @return the value of the object's {@code accessible} flag
+     */
+    public boolean isAccessible() {
+        return override;
+    }
+
+    /**
+     * Constructor: only used by the Java Virtual Machine.
+     */
+    protected AccessibleObject() {}
+
+    // Indicates whether language-level access checks are overridden
+    // by this object. Initializes to "false". This field is used by
+    // Field, Method, and Constructor.
+    //
+    // NOTE: for security purposes, this field must not be visible
+    // outside this package.
+    boolean override;
+
+    // Reflection factory used by subclasses for creating field,
+    // method, and constructor accessors. Note that this is called
+    // very early in the bootstrapping process.
+    static final ReflectionFactory reflectionFactory = (ReflectionFactory)
+        AccessController.doPrivileged
+            (new sun.reflect.ReflectionFactory.GetReflectionFactoryAction());
+
+    /**
+     * @throws NullPointerException {@inheritDoc}
+     * @since 1.5
+     */
+    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
+        throw new AssertionError("All subclasses should override this method");
+    }
+
+    /**
+     * @throws NullPointerException {@inheritDoc}
+     * @since 1.5
+     */
+    public boolean isAnnotationPresent(
+        Class<? extends Annotation> annotationClass) {
+        return getAnnotation(annotationClass) != null;
+    }
+
+    /**
+     * @since 1.5
+     */
+    public Annotation[] getAnnotations() {
+        return getDeclaredAnnotations();
+    }
+
+    /**
+     * @since 1.5
+     */
+    public Annotation[] getDeclaredAnnotations()  {
+        throw new AssertionError("All subclasses should override this method");
+    }
+}