src/java/org/apache/sqoop/util/Jars.java

/**
 * 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.sqoop.util;

import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.Enumeration;

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

import org.apache.sqoop.manager.ConnManager;

/**
 * Utility class; returns the locations of various jars.
 */
public final class Jars {

  public static final Log LOG = LogFactory.getLog(
      Jars.class.getName());

  private Jars() {
  }

  /**
   * @return the path to the main Sqoop jar.
   */
  public static String getSqoopJarPath() {
    return getJarPathForClass(Jars.class);
  }

  /**
   * Return the jar file path that contains a particular class.
   * Method mostly cloned from o.a.h.mapred.JobConf.findContainingJar().
   */
  public static String getJarPathForClass(Class<? extends Object> classObj) {
    ClassLoader loader = classObj.getClassLoader();
    String classFile = classObj.getName().replaceAll("\\.", "/") + ".class";
    try {
      for (Enumeration<URL> itr = loader.getResources(classFile);
          itr.hasMoreElements();) {
        URL url = (URL) itr.nextElement();
        if ("jar".equals(url.getProtocol())) {
          String toReturn = url.getPath();
          if (toReturn.startsWith("file:")) {
            toReturn = toReturn.substring("file:".length());
          }
          // URLDecoder is a misnamed class, since it actually decodes
          // x-www-form-urlencoded MIME type rather than actual
          // URL encoding (which the file path has). Therefore it would
          // decode +s to ' 's which is incorrect (spaces are actually
          // either unencoded or encoded as "%20"). Replace +s first, so
          // that they are kept sacred during the decoding process.
          toReturn = toReturn.replaceAll("\\+", "%2B");
          toReturn = URLDecoder.decode(toReturn, "UTF-8");
          return toReturn.replaceAll("!.*$", "");
        }
      }
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    return null;
  }

  /**
   * Return the path to the jar containing the JDBC driver
   * for a ConnManager.
   */
  public static String getDriverClassJar(ConnManager mgr) {
    if (null == mgr) {
      return null;
    }

    String driverClassName = mgr.getDriverClass();
    if (null == driverClassName) {
      return null;
    }

    try {
      Class<? extends Object> driverClass = Class.forName(driverClassName);
      return getJarPathForClass(driverClass);
    } catch (ClassNotFoundException cnfe) {
      LOG.warn("No such class " + driverClassName + " available.");
      return null;
    }
  }

}