edu.vt.middleware.ldap.ssl.AbstractCredentialReader.java Source code

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Here is the source code for edu.vt.middleware.ldap.ssl.AbstractCredentialReader.java

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/*
  $Id$
    
  Copyright (C) 2003-2010 Virginia Tech.
  All rights reserved.
    
  SEE LICENSE FOR MORE INFORMATION
    
  Author:  Middleware Services
  Email:   middleware@vt.edu
  Version: $Revision$
  Updated: $Date$
*/
package edu.vt.middleware.ldap.ssl;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Base class for all credential readers. It provides support for loading files
 * from resources on the classpath or a filepath. If a path is prefixed with the
 * string "classpath:" it is interpreted as a classpath specification. If a path
 * is prefixed with the string "file:" it is interpreted as a file path. Any
 * other input throws IllegalArgumentException.
 *
 * @param  <T>  Type of credential read by this instance.
 *
 * @author  Middleware Services
 * @version  $Revision$
 */
public abstract class AbstractCredentialReader<T> implements CredentialReader<T> {

    /** Prefix used to indicate a classpath resource. */
    public static final String CLASSPATH_PREFIX = "classpath:";

    /** Prefix used to indicate a file resource. */
    public static final String FILE_PREFIX = "file:";

    /** Start index of path specification when given a classpath resource. */
    private static final int CLASSPATH_START_INDEX = CLASSPATH_PREFIX.length();

    /** Start index of path specification when given a file resource. */
    private static final int FILE_START_INDEX = FILE_PREFIX.length();

    /** Log for this class. */
    protected final Log logger = LogFactory.getLog(this.getClass());

    /** {@inheritDoc} */
    public T read(final String path, final String... params) throws IOException, GeneralSecurityException {
        InputStream is = null;
        if (path.startsWith(CLASSPATH_PREFIX)) {
            is = getClass().getResourceAsStream(path.substring(CLASSPATH_START_INDEX));
        } else if (path.startsWith(FILE_PREFIX)) {
            is = new FileInputStream(new File(path.substring(FILE_START_INDEX)));
        } else {
            throw new IllegalArgumentException(
                    "path must start with either " + CLASSPATH_PREFIX + " or " + FILE_PREFIX);
        }
        if (is != null) {
            try {
                return read(is, params);
            } finally {
                if (this.logger.isDebugEnabled()) {
                    this.logger.debug("Successfully loaded " + path);
                }
                is.close();
            }
        } else {
            if (this.logger.isDebugEnabled()) {
                this.logger.debug("Failed to load " + path);
            }
            return null;
        }
    }

    /** {@inheritDoc} */
    public abstract T read(InputStream is, String... params) throws IOException, GeneralSecurityException;

    /**
     * Gets a buffered input stream from the given input stream. If the given
     * instance is already buffered, it is simply returned.
     *
     * @param  is  Input stream from which to create buffered instance.
     *
     * @return  Buffered input stream. If the given instance is already buffered,
     * it is simply returned.
     */
    protected InputStream getBufferedInputStream(final InputStream is) {
        if (is.markSupported()) {
            return is;
        } else {
            return new BufferedInputStream(is);
        }
    }
}