org.eclipse.gyrex.jobs.internal.util.ContextHashUtil.java Source code

Introduction

Here is the source code for org.eclipse.gyrex.jobs.internal.util.ContextHashUtil.java

Source

/*******************************************************************************
 * Copyright (c) 2013 AGETO Service GmbH and others.
 * All rights reserved.
 *  
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html.
 * 
 * Contributors:
 *     Gunnar Wagenknecht - initial API and implementation
 *******************************************************************************/
package org.eclipse.gyrex.jobs.internal.util;

import java.io.UnsupportedEncodingException;

import org.eclipse.gyrex.context.IRuntimeContext;

import org.eclipse.core.runtime.IPath;

import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.lang.CharEncoding;
import org.apache.commons.lang.StringUtils;

/**
 * A utility for generating consistent context hashes for a context.
 */
public class ContextHashUtil {

    private static final String SEPARATOR = "_";

    public static String getExternalId(final String internalId) {
        final int i = internalId.indexOf(SEPARATOR);
        if (i < 0)
            return internalId;
        return internalId.substring(i + 1);
    }

    private static String getInternalIdPrefix(final IPath contextPath) {
        try {
            return DigestUtils.shaHex(contextPath.toString().getBytes(CharEncoding.UTF_8)) + SEPARATOR;
        } catch (final UnsupportedEncodingException e) {
            throw new IllegalStateException("Please use a JVM that supports UTF-8.");
        }
    }

    private final String internalIdPrefix;

    /**
     * Creates a new instance.
     */
    public ContextHashUtil(final IPath contextPath) {
        internalIdPrefix = getInternalIdPrefix(contextPath);
    }

    /**
     * Creates a new instance.
     */
    public ContextHashUtil(final IRuntimeContext context) {
        internalIdPrefix = getInternalIdPrefix(context.getContextPath());
    }

    /**
     * @return <code>true</code> if the specified internal id starts with the
     *         same hash used by this util
     */
    public boolean isInternalId(final String internalId) {
        return (internalId != null) && internalId.startsWith(internalIdPrefix);
    }

    public String toExternalId(final String internalId) {
        return StringUtils.removeStart(internalId, internalIdPrefix);
    }

    public String toInternalId(final String id) {
        return internalIdPrefix.concat(id);
    }

    @Override
    public String toString() {
        return internalIdPrefix;
    }
}