com.jpeterson.littles3.bo.Resource.java Source code

Introduction

Here is the source code for com.jpeterson.littles3.bo.Resource.java

Source

/*
 * Copyright 2007 Jesse Peterson
 * 
 * Licensed 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 com.jpeterson.littles3.bo;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.security.AccessControlException;
import java.security.Permission;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * General base functionality for S3 bucket and object items.
 * 
 * @author Jesse Peterson
 */
public abstract class Resource implements Serializable {
    /**
     * If incompatible serialization changes are made, mostly deleting methods,
     * this must be changed.
     */
    private static final long serialVersionUID = 1L;

    private Acp acp;

    transient protected Log logger;

    /**
     * Basic constructor.
     */
    public Resource() {
        init();
    }

    /**
     * Initialization routines. Allows the <code>transient</code> to be
     * initialized when deserialized.
     */
    private void init() {
        logger = LogFactory.getLog(this.getClass());
    }

    /**
     * Get the Access Control Policy (ACP) for this resource.
     * 
     * @return The Access Control Policy (ACP) for this resource.
     */
    public Acp getAcp() {
        return acp;
    }

    /**
     * Set the Access Control Policy (ACP) for this resource.
     * 
     * @param acp
     *            The Access Control Policy for this resource.
     */
    public void setAcp(Acp acp) {
        this.acp = acp;
    }

    /**
     * Determines if the <code>principal</code> can "read" the resource. The
     * meaning of "read" depends on the particular implementation of the
     * resource.
     * 
     * @param grantee
     *            The entity to check and see if they can "read" the resource.
     *            This is typically the authenticated principal requesting to
     *            read the resource.
     * @throws AccessControlException
     *             Thrown if the <code>principal</code> can not "read" the
     *             resource.
     */
    public void canRead(Grantee grantee) throws AccessControlException {
        if (acp == null) {
            throw new AccessControlException("Access Control Policy is null, therefore, no grants");
        }

        Permission permission = new ResourcePermission(grantee, ResourcePermission.ACTION_READ);
        acp.checkPermission(permission);
    }

    /**
     * Determines if the <code>principal</code> can "write" the resource. The
     * meaning of "write" depends on the particular implementation of the
     * resource.
     * 
     * @param grantee
     *            The entity to check and see if they can "write" the resource.
     *            This is typically the authenticated principal requesting to
     *            write the resource.
     * @throws AccessControlException
     *             Thrown if the <code>principal</code> can not "write" the
     *             resource.
     */
    public void canWrite(Grantee grantee) throws AccessControlException {
        if (acp == null) {
            throw new AccessControlException("Access Control Policy is null, therefore, no grants");
        }

        Permission permission = new ResourcePermission(grantee, ResourcePermission.ACTION_WRITE);
        acp.checkPermission(permission);
    }

    private void writeObject(ObjectOutputStream out) throws IOException {
        out.defaultWriteObject();
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();

        // initialize transient variable(s)
        init();
    }
}