org.apache.jena.security.impl.CachedSecurityEvaluator.java Source code

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Here is the source code for org.apache.jena.security.impl.CachedSecurityEvaluator.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jena.security.impl;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.security.Principal;
import java.util.LinkedHashSet;
import java.util.Set;

import org.apache.commons.lang.ClassUtils;
import org.apache.jena.security.SecurityEvaluator;

/**
 * A SecurityEvaluator that can be cached for later use.
 */
public class CachedSecurityEvaluator implements InvocationHandler {
    private final SecurityEvaluator wrapped;
    private final Principal origPrincipal;

    // The getPrincipal() method.
    private static Method GET_PRINCIPAL;

    static {
        try {
            CachedSecurityEvaluator.GET_PRINCIPAL = SecurityEvaluator.class.getMethod("getPrincipal");
        } catch (final SecurityException e) {
            throw new RuntimeException(e);
        } catch (final NoSuchMethodException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Create an instance.
     * @param evaluator The security evaluator we are caching.
     * @param runAs The principal that we want to use when checking the permissions.
     * @return The proxied SecurityEvaluator.
     */
    public static SecurityEvaluator getInstance(final SecurityEvaluator evaluator, final Principal runAs) {
        final Set<Class<?>> ifac = new LinkedHashSet<Class<?>>();
        if (evaluator.getClass().isInterface()) {
            ifac.add(evaluator.getClass());
        }
        ifac.addAll(ClassUtils.getAllInterfaces(evaluator.getClass()));

        return (SecurityEvaluator) Proxy.newProxyInstance(SecuredItemImpl.class.getClassLoader(),
                ifac.toArray(new Class<?>[ifac.size()]), new CachedSecurityEvaluator(evaluator, runAs));
    }

    /**
     * 
     * @param wrapped
     * @param runAs
     */
    private CachedSecurityEvaluator(final SecurityEvaluator wrapped, final Principal runAs) {
        origPrincipal = runAs;
        this.wrapped = wrapped;
    }

    @Override
    public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
        // check for the special case methods
        if (CachedSecurityEvaluator.GET_PRINCIPAL.equals(method)) {
            return origPrincipal;
        }

        // if we get here then the method is not being proxied so call the
        // original method
        // on the base item.
        return method.invoke(wrapped, args);

    }
}