org.apache.hawq.pxf.service.utilities.Utilities.java Source code

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Here is the source code for org.apache.hawq.pxf.service.utilities.Utilities.java

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package org.apache.hawq.pxf.service.utilities;

/*
 * 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.
 */

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hawq.pxf.api.utilities.InputData;

/**
 * Utilities class exposes helper method for PXF classes
 */
public class Utilities {
    private static final Log LOG = LogFactory.getLog(Utilities.class);

    /**
     * Creates an object using the class name. The class name has to be a class
     * located in the webapp's CLASSPATH.
     *
     * @param confClass the class of the metaData used to initialize the
     *            instance
     * @param className a class name to be initialized.
     * @param metaData input data used to initialize the class
     * @return Initialized instance of given className
     * @throws Exception throws exception if classname was not found in
     *             classpath, didn't have expected constructor or failed to be
     *             instantiated
     */
    public static Object createAnyInstance(Class<?> confClass, String className, InputData metaData)
            throws Exception {

        Class<?> cls = null;
        try {
            cls = Class.forName(className);
        } catch (ClassNotFoundException e) {
            // in case the class name uses the old "com.pivotal.pxf" package
            // name, recommend using the new package "org.apache.hawq.pxf".
            if (className.startsWith("com.pivotal.pxf")) {
                throw new Exception("Class " + className + " does not appear in classpath. "
                        + "Plugins provided by PXF must start with \"org.apache.hawq.pxf\"", e.getCause());
            } else {
                throw e;
            }
        }

        Constructor<?> con = cls.getConstructor(confClass);

        return instantiate(con, metaData);
    }

    /**
     * Creates an object using the class name with its default constructor. The
     * class name has to be a class located in the webapp's CLASSPATH.
     *
     * @param className a class name to be initialized
     * @return initialized instance of given className
     * @throws Exception throws exception if classname was not found in
     *             classpath, didn't have expected constructor or failed to be
     *             instantiated
     */
    public static Object createAnyInstance(String className) throws Exception {
        Class<?> cls = Class.forName(className);
        Constructor<?> con = cls.getConstructor();
        return instantiate(con);
    }

    private static Object instantiate(Constructor<?> con, Object... args) throws Exception {
        try {
            return con.newInstance(args);
        } catch (InvocationTargetException e) {
            /*
             * We are creating resolvers, accessors, fragmenters, etc. using the
             * reflection framework. If for example, a resolver, during its
             * instantiation - in the c'tor, will throw an exception, the
             * Resolver's exception will reach the Reflection layer and there it
             * will be wrapped inside an InvocationTargetException. Here we are
             * above the Reflection layer and we need to unwrap the Resolver's
             * initial exception and throw it instead of the wrapper
             * InvocationTargetException so that our initial Exception text will
             * be displayed in psql instead of the message:
             * "Internal Server Error"
             */
            throw (e.getCause() != null) ? new Exception(e.getCause()) : e;
        }
    }

    /**
     * Transforms a byte array into a string of octal codes in the form
     * \\xyz\\xyz
     *
     * We double escape each char because it is required in postgres bytea for
     * some bytes. In the minimum all non-printables, backslash, null and single
     * quote. Easier to just escape everything see
     * http://www.postgresql.org/docs/9.0/static/datatype-binary.html
     *
     * Octal codes must be padded to 3 characters (001, 012)
     *
     * @param bytes bytes to escape
     * @param sb octal codes of given bytes
     */
    public static void byteArrayToOctalString(byte[] bytes, StringBuilder sb) {
        if ((bytes == null) || (sb == null)) {
            return;
        }

        sb.ensureCapacity(sb.length() + (bytes.length * 5 /* characters per byte */));
        for (int b : bytes) {
            sb.append(String.format("\\\\%03o", b & 0xff));
        }
    }

    /**
     * Replaces any non-alpha-numeric character with a '.'. This measure is used
     * to prevent cross-site scripting (XSS) when an input string might include
     * code or script. By removing all special characters and returning a
     * censured string to the user this threat is avoided.
     *
     * @param input string to be masked
     * @return masked string
     */
    public static String maskNonPrintables(String input) {
        if (StringUtils.isEmpty(input)) {
            return input;
        }
        return input.replaceAll("[^a-zA-Z0-9_:/-]", ".");
    }
}