com.cloudera.hoop.fs.FSUtils.java Source code

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Here is the source code for com.cloudera.hoop.fs.FSUtils.java

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/*
 * Copyright (c) 2011, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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 com.cloudera.hoop.fs;

import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

import java.net.URI;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * File system utilities used by Hoop classes.
 */
public class FSUtils {

    /**
     * Constant for the default permission string ('default').
     */
    public static final String DEFAULT_PERMISSION = "default";

    /**
     * Converts a Unix permission symbolic representation
     * (i.e. -rwxr--r--) into a Hadoop permission.
     *
     * @param str Unix permission symbolic representation.
     * @return the Hadoop permission. If the given string was
     * 'default', it returns <code>FsPermission.getDefault()</code>.
     */
    public static FsPermission getPermission(String str) {
        FsPermission permission;
        if (str.equals(DEFAULT_PERMISSION)) {
            permission = FsPermission.getDefault();
        } else {
            //TODO: there is something funky here, it does not detect 'x'
            permission = FsPermission.valueOf(str);
        }
        return permission;
    }

    /**
     * Replaces the <code>SCHEME://HOST:PORT</code> of a Hadoop
     * <code>Path</code> with the specified base URL.
     *
     * @param path Hadoop path to replace the
     * <code>SCHEME://HOST:PORT</code>.
     * @param hoopBaseUrl base URL to replace it with.
     * @return the path using the given base URL.
     */
    public static Path convertPathToHoop(Path path, String hoopBaseUrl) {
        URI uri = path.toUri();
        String filePath = uri.getRawPath();
        String hoopPath = hoopBaseUrl + filePath;
        return new Path(hoopPath);
    }

    /**
     * Converts a Hadoop permission into a Unix permission symbolic
     * representation (i.e. -rwxr--r--) or default if the permission is NULL.
     *
     * @param p Hadoop permission.
     * @return the Unix permission symbolic representation or default if the
     * permission is NULL.
     */
    private static String permissionToString(FsPermission p) {
        return (p == null) ? "default"
                : "-" + p.getUserAction().SYMBOL + p.getGroupAction().SYMBOL + p.getOtherAction().SYMBOL;
    }

    /**
     * Converts a Hadoop <code>FileStatus</code> object into a JSON array
     * object. It replaces the <code>SCHEME://HOST:PORT</code> of the path
     * with the  specified URL.
     * <p/>
     * @param status Hadoop file status.
     * @param hoopBaseUrl base URL to replace the
     * <code>SCHEME://HOST:PORT</code> in the file status.
     * @return The JSON representation of the file status.
     */
    @SuppressWarnings("unchecked")
    public static Map fileStatusToJSON(FileStatus status, String hoopBaseUrl) {
        Map json = new LinkedHashMap();
        json.put("path", convertPathToHoop(status.getPath(), hoopBaseUrl).toString());
        json.put("isDir", status.isDir());
        json.put("len", status.getLen());
        json.put("owner", status.getOwner());
        json.put("group", status.getGroup());
        json.put("permission", permissionToString(status.getPermission()));
        json.put("accessTime", status.getAccessTime());
        json.put("modificationTime", status.getModificationTime());
        json.put("blockSize", status.getBlockSize());
        json.put("replication", status.getReplication());
        return json;
    }

    /**
     * Converts a Hadoop <code>FileStatus</code> array into a JSON array
     * object. It replaces the <code>SCHEME://HOST:PORT</code> of the path
     * with the  specified URL.
     * <p/>
     * @param status Hadoop file status array.
     * @param hoopBaseUrl base URL to replace the
     * <code>SCHEME://HOST:PORT</code> in the file status.
     * @return The JSON representation of the file status array.
     */
    @SuppressWarnings("unchecked")
    public static JSONArray fileStatusToJSON(FileStatus[] status, String hoopBaseUrl) {
        JSONArray json = new JSONArray();
        if (status != null) {
            for (FileStatus s : status) {
                json.add(fileStatusToJSON(s, hoopBaseUrl));
            }
        }
        return json;
    }

    /**
     * Converts an object into a Json Map with with one key-value entry.
     * <p/>
     * It assumes the given value is either a JSON primitive type or a
     * <code>JsonAware</code> instance.
     *
     * @param name name for the key of the entry.
     * @param value for the value of the entry.
     * @return the JSON representation of the key-value pair.
     */
    @SuppressWarnings("unchecked")
    public static JSONObject toJSON(String name, Object value) {
        JSONObject json = new JSONObject();
        json.put(name, value);
        return json;
    }
}