org.apache.hadoop.hdfs.server.common.Util.java Source code

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Here is the source code for org.apache.hadoop.hdfs.server.common.Util.java

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/**
 * 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.hadoop.hdfs.server.common;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;

@InterfaceAudience.Private
public final class Util {
    private final static Log LOG = LogFactory.getLog(Util.class.getName());

    /**
     * Interprets the passed string as a URI. In case of error it
     * assumes the specified string is a file.
     *
     * @param s
     *     the string to interpret
     * @return the resulting URI
     * @throws IOException
     */
    public static URI stringAsURI(String s) throws IOException {
        URI u = null;
        // try to make a URI
        try {
            u = new URI(s);
        } catch (URISyntaxException e) {
            LOG.error("Syntax error in URI " + s + ". Please check hdfs configuration.", e);
        }

        // if URI is null or scheme is undefined, then assume it's file://
        if (u == null || u.getScheme() == null) {
            LOG.warn("Path " + s + " should be specified as a URI "
                    + "in configuration files. Please update hdfs configuration.");
            u = fileAsURI(new File(s));
        }
        return u;
    }

    /**
     * Converts the passed File to a URI. This method trims the trailing slash if
     * one is appended because the underlying file is in fact a directory that
     * exists.
     *
     * @param f
     *     the file to convert
     * @return the resulting URI
     * @throws IOException
     */
    public static URI fileAsURI(File f) throws IOException {
        URI u = f.getCanonicalFile().toURI();

        // trim the trailing slash, if it's present
        if (u.getPath().endsWith("/")) {
            String uriAsString = u.toString();
            try {
                u = new URI(uriAsString.substring(0, uriAsString.length() - 1));
            } catch (URISyntaxException e) {
                throw new IOException(e);
            }
        }

        return u;
    }

    /**
     * Converts a collection of strings into a collection of URIs.
     *
     * @param names
     *     collection of strings to convert to URIs
     * @return collection of URIs
     */
    public static List<URI> stringCollectionAsURIs(Collection<String> names) {
        List<URI> uris = new ArrayList<>(names.size());
        for (String name : names) {
            try {
                uris.add(stringAsURI(name));
            } catch (IOException e) {
                LOG.error("Error while processing URI: " + name, e);
            }
        }
        return uris;
    }
}