ch.lipsch.subsonic4j.internal.SubsonicUtil.java Source code

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Here is the source code for ch.lipsch.subsonic4j.internal.SubsonicUtil.java

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/*
 * Copyright (C) 2011 Erwin Betschart
 * 
 * This file is part of Subsonic4J.
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program; If not, see <http://www.gnu.org/licenses/>.
 */
package ch.lipsch.subsonic4j.internal;

import java.io.UnsupportedEncodingException;
import java.net.URL;

import org.apache.commons.httpclient.URIException;
import org.apache.commons.httpclient.util.URIUtil;
import org.subsonic.restapi.Response;
import org.subsonic.restapi.ResponseStatus;

import ch.lipsch.subsonic4j.CredentialsProvider;
import ch.lipsch.subsonic4j.SubsonicException;
import ch.lipsch.subsonic4j.SubsonicException.ErrorType;
import ch.lipsch.subsonic4j.tools.StateChecker;

public final class SubsonicUtil {

    private static final String REST_PATH = "rest";
    private static final String SUBSONIC_VERSION = "1.4.0";
    private static final String CLIENT_APP = "subs4j";

    private SubsonicUtil() {
    }

    private static String addSlashIfNecessary(String url) {
        if (!url.endsWith("/")) {
            return url + "/";
        }
        return url;
    }

    /**
     * Appends a key value pair to an url if the value is set. Must only be used
     * there is already a parameter set on the url. * @param url
     * 
     * @param key
     *            The parameter name. May be <code>null</code>.
     * @param value
     *            The value. May be <code>null</code>.
     * @return The key & value added to the url:
     *         http://12.34.56.78?first=bla&key=value
     * @throws SubsonicException
     *             In case the value can not be encode to fit into the url.
     */
    public static String appendIfSet(String url, String key, String value) throws SubsonicException {
        if (key != null && value != null) {
            try {
                return url + "&" + key + "=" + URIUtil.encodeWithinQuery(value);
            } catch (URIException e) {
                throw new SubsonicException(ErrorType.GENERIC, e);
            }
        } else {
            return url;
        }
    }

    public static String appendCredentialsAsFirstParam(String url, CredentialsProvider credentials) {
        StringBuilder sb = new StringBuilder();
        sb.append(url);
        sb.append("?u=");
        sb.append(credentials.getUserName());
        sb.append("&p=");
        sb.append(SubsonicUtil.hexEncodePassword(credentials.getPassword()));
        sb.append("&v=");
        sb.append(SUBSONIC_VERSION);
        sb.append("&c=");
        sb.append(CLIENT_APP);
        return sb.toString();
    }

    public static String restifySubsonicUrl(URL url, String view) {
        StateChecker.check(url, "url");
        StateChecker.check(view, "view");
        String restifiedUrl = url.toString();
        restifiedUrl = addSlashIfNecessary(restifiedUrl);
        restifiedUrl += REST_PATH;
        restifiedUrl = addSlashIfNecessary(restifiedUrl);
        restifiedUrl += view;
        return restifiedUrl;
    }

    public static void throwExceptionIfNecessary(Response response) throws SubsonicException {
        if (response.getStatus().equals(ResponseStatus.FAILED)) {
            throw new SubsonicException(response.getError().getMessage(), response.getError().getCode());
        }
    }

    /**
     * Copied from subsonic source (Util.java).
     * 
     * Converts an array of bytes into an array of characters representing the
     * hexadecimal values of each byte in order. The returned array will be
     * double the length of the passed array, as it takes two characters to
     * represent any given byte.
     * 
     * @param data
     *            Bytes to convert to hexadecimal characters.
     * @return A string containing hexadecimal characters.
     */
    public static String hexEncodePassword(String password) {
        final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
                'f' };

        byte[] passwordInBytes;
        try {
            passwordInBytes = password.getBytes("UTF-8");
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }

        int length = passwordInBytes.length;
        char[] out = new char[length << 1];
        // two characters form the hex value.
        for (int i = 0, j = 0; i < length; i++) {
            out[j++] = HEX_DIGITS[(0xF0 & passwordInBytes[i]) >>> 4];
            out[j++] = HEX_DIGITS[0x0F & passwordInBytes[i]];
        }

        String encodedPass = new String(out);
        encodedPass = "enc:" + encodedPass;
        return encodedPass;
    }
}