    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *     https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.configuration2.io;
    018
    019import java.io.File;
    020import java.io.IOException;
    021import java.net.URL;
    022
    023import org.apache.commons.lang3.StringUtils;
    024import org.apache.commons.lang3.SystemProperties;
    025
    026/**
    027 * A specialized implementation of {@code FileLocationStrategy} which searches for files in the user's home directory or
    028 * another special configurable directory.
    029 * <p>
    030 * This strategy implementation ignores the URL stored in the passed in {@link FileLocator}. It constructs a file path
    031 * from the configured home directory (which is the user's home directory per default, but can be changed to another
    032 * path), optionally the base path, and the file name. If the resulting path points to an existing file, its URL is
    033 * returned.
    034 * </p>
    035 * <p>
    036 * When constructing an instance it can be configured whether the base path should be taken into account. If this option
    037 * is set, the base path is appended to the home directory if it is not {@code null}. This is useful for instance to
    038 * select a specific sub directory of the user's home directory. If this option is set to <strong>false</strong>, the base path is
    039 * always ignored, and only the file name is evaluated.
    040 * </p>
    041 * <p>
    042 * See {@link AbstractFileLocationStrategy} learn how to grant an deny URL schemes and hosts.
    043 * </p>
    044 *
    045 * @see AbstractFileLocationStrategy
    046 */
    047public class HomeDirectoryLocationStrategy extends AbstractFileLocationStrategy {
    048
    049    /**
    050     * Builds new instances of {@link HomeDirectoryLocationStrategy}.
    051     *
    052     * @since 2.15.0
    053     */
    054    public static class Builder extends AbstractBuilder<HomeDirectoryLocationStrategy, Builder> {
    055
    056        /** The flag whether the base path is to be taken into account. */
    057        private boolean evaluateBasePath;
    058
    059        /** The home directory to be searched for the requested file. */
    060        private String homeDirectory;
    061
    062        /**
    063         * Constructs a new instance.
    064         */
    065        public Builder() {
    066            // empty
    067        }
    068
    069        @Override
    070        public HomeDirectoryLocationStrategy get() throws IOException {
    071            return new HomeDirectoryLocationStrategy(this);
    072        }
    073
    074        /**
    075         * Sets whether the base path should be evaluated.
    076         *
    077         * @param evaluateBasePath whether the base path should be evaluated.
    078         * @return {@code this} instance..
    079         */
    080        public Builder setEvaluateBasePath(final boolean evaluateBasePath) {
    081            this.evaluateBasePath = evaluateBasePath;
    082            return asThis();
    083        }
    084
    085        /**
    086         * Sets the path to the home directory (may be {@code null}).
    087         *
    088         * @param homeDirectory the path to the home directory (may be {@code null})
    089         * @return {@code this} instance..
    090         */
    091        public Builder setHomeDirectory(final String homeDirectory) {
    092            this.homeDirectory = homeDirectory;
    093            return asThis();
    094        }
    095    }
    096
    097    /**
    098     * Gets the home directory to be used by a new instance. If a directory name is provided, it is used. Otherwise, the
    099     * user's home directory is looked up.
    100     *
    101     * @param homeDir the passed in home directory
    102     * @return the directory to be used
    103     */
    104    private static String getHomeDirectory(final String homeDir) {
    105        return homeDir != null ? homeDir : SystemProperties.getUserHome();
    106    }
    107
    108    /** The flag whether the base path is to be taken into account. */
    109    private final boolean evaluateBasePath;
    110
    111    /** The home directory to be searched for the requested file. */
    112    private final String homeDirectory;
    113
    114    /**
    115     * Creates a new instance of {@code HomeDirectoryLocationStrategy} with default settings. The home directory is set to
    116     * the user's home directory. The base path flag is set to <strong>false</strong> (which means that the base path is ignored).
    117     */
    118    public HomeDirectoryLocationStrategy() {
    119        this(false);
    120    }
    121
    122    /**
    123     * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes the base path flag. The home
    124     * directory is set to the user's home directory.
    125     *
    126     * @param withBasePath a flag whether the base path should be evaluated.
    127     * @deprecated Use {@link Builder#setEvaluateBasePath(boolean)}.
    128     */
    129    @Deprecated
    130    public HomeDirectoryLocationStrategy(final boolean withBasePath) {
    131        this(new Builder().setHomeDirectory(null).setEvaluateBasePath(withBasePath));
    132    }
    133
    134    /**
    135     * Constructs a new instance.
    136     *
    137     * @param builder How to build the instance.
    138     */
    139    private HomeDirectoryLocationStrategy(final Builder builder) {
    140        super(builder);
    141        homeDirectory = getHomeDirectory(builder.homeDirectory);
    142        evaluateBasePath = builder.evaluateBasePath;
    143    }
    144
    145    /**
    146     * Creates a new instance of {@code HomeDirectoryLocationStrategy} and initializes it with the specified settings.
    147     *
    148     * @param homeDir the path to the home directory (may be {@code null}).
    149     * @param withBasePath a flag whether the base path should be evaluated.
    150     * @deprecated Use {@link Builder#setHomeDirectory(String)}.
    151     */
    152    @Deprecated
    153    public HomeDirectoryLocationStrategy(final String homeDir, final boolean withBasePath) {
    154        this(new Builder().setHomeDirectory(homeDir).setEvaluateBasePath(withBasePath));
    155    }
    156
    157    /**
    158     * Determines the base path to be used for the current locate() operation.
    159     *
    160     * @param locator the {@code FileLocator}
    161     * @return the base path to be used
    162     */
    163    private String getBasePath(final FileLocator locator) {
    164        if (isEvaluateBasePath() && StringUtils.isNotEmpty(locator.getBasePath())) {
    165            return FileLocatorUtils.appendPath(getHomeDirectory(), locator.getBasePath());
    166        }
    167        return getHomeDirectory();
    168    }
    169
    170    /**
    171     * Gets the home directory. In this directory the strategy searches for files.
    172     *
    173     * @return the home directory used by this object.
    174     */
    175    public String getHomeDirectory() {
    176        return homeDirectory;
    177    }
    178
    179    /**
    180     * Returns a flag whether the base path is to be taken into account when searching for a file.
    181     *
    182     * @return the flag whether the base path is evaluated
    183     */
    184    public boolean isEvaluateBasePath() {
    185        return evaluateBasePath;
    186    }
    187
    188    /**
    189     * {@inheritDoc} This implementation searches in the home directory for a file described by the passed in
    190     * {@code FileLocator}. If the locator defines a base path and the {@code evaluateBasePath} property is <strong>true</strong>, a
    191     * sub directory of the home directory is searched.
    192     */
    193    @Override
    194    public URL locate(final FileSystem fileSystem, final FileLocator locator) {
    195        if (StringUtils.isNotEmpty(locator.getFileName())) {
    196            final String basePath = getBasePath(locator);
    197            final File file = FileLocatorUtils.constructFile(basePath, locator.getFileName());
    198            if (file.isFile()) {
    199                return check(FileLocatorUtils.convertFileToURL(file));
    200            }
    201        }
    202        return null;
    203    }
    204}