Android - Helper for accessing os properties.

BuildProperties.java

package cc.cubone.turbo.core.os;

import android.os.Environment;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class BuildProperties {

    private final Properties properties;

    private BuildProperties() throws IOException {
        InputStream in = new FileInputStream(new File(Environment.getRootDirectory(), "build.prop"));
        properties = new Properties();
        properties.load(in);
        in.close();
    }

    public static BuildProperties newInstance() throws IOException {
        return new BuildProperties();
    }

    public boolean containsKey(final Object key) {
        return properties.containsKey(key);
    }

    public boolean containsValue(final Object value) {
        return properties.containsValue(value);
    }

    public Set<Map.Entry<Object, Object>> entrySet() {
        return properties.entrySet();
    }

    public String getProperty(final String name) {
        return properties.getProperty(name);
    }

    public String getProperty(final String name, final String defaultValue) {
        return properties.getProperty(name, defaultValue);
    }

    public boolean isEmpty() {
        return properties.isEmpty();
    }

    public Enumeration<Object> keys() {
        return properties.keys();
    }

    public Set<Object> keySet() {
        return properties.keySet();
    }

    public int size() {
        return properties.size();
    }

    public Collection<Object> values() {
        return properties.values();
    }
}

SystemProperties.java

/*
 * Copyright (C) 2015 Jared Rummler
 *
 * Licensed 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 cc.cubone.turbo.core.os;

/**
 * Gives access to the system properties store. The system properties store contains a list of
 * string key-value pairs.
 *
 * @see <a href="http://stackoverflow.com/questions/2641111/where-is-android-os-systemproperties">
 * Where is android.os.SystemProperties</a>
 */
public class SystemProperties {

    private static final Class<?> SP = getSystemPropertiesClass();

    private SystemProperties() {
        throw new AssertionError();
    }

    /**
     * Get the value for the given key.
     */
    public static String get(String key) {
        try {
            return (String) SP.getMethod("get", String.class).invoke(null, key);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * Get the value for the given key.
     *
     * @return if the key isn't found, return def if it isn't null, or an empty string otherwise
     */
    public static String get(String key, String def) {
        try {
            return (String) SP.getMethod("get", String.class, String.class).invoke(null, key, def);
        } catch (Exception e) {
            return def;
        }
    }

    /**
     * Get the value for the given key, returned as a boolean. Values 'n', 'no', '0', 'false' or
     * 'off' are considered false. Values 'y', 'yes', '1', 'true' or 'on' are considered true. (case
     * sensitive). If the key does not exist, or has any other value, then the default result is
     * returned.
     *
     * @param key the key to lookup
     * @param def a default value to return
     * @return the key parsed as a boolean, or def if the key isn't found or is not able to be
     * parsed as a boolean.
     */
    public static boolean getBoolean(String key, boolean def) {
        try {
            return (Boolean) SP.getMethod("getBoolean", String.class, boolean.class)
                    .invoke(null, key, def);
        } catch (Exception e) {
            return def;
        }
    }

    /**
     * Get the value for the given key, and return as an integer.
     *
     * @param key the key to lookup
     * @param def a default value to return
     * @return the key parsed as an integer, or def if the key isn't found or cannot be parsed
     */
    public static int getInt(String key, int def) {
        try {
            return (Integer) SP.getMethod("getInt", String.class, int.class).invoke(null, key, def);
        } catch (Exception e) {
            return def;
        }
    }

    /**
     * Get the value for the given key, and return as a long.
     *
     * @param key the key to lookup
     * @param def a default value to return
     * @return the key parsed as a long, or def if the key isn't found or cannot be parsed
     */
    public static long getLong(String key, long def) {
        try {
            return (Long) SP.getMethod("getLong", String.class, long.class).invoke(null, key, def);
        } catch (Exception e) {
            return def;
        }
    }

    /**
     * Set the value for the given key.
     * <p>
     * <b>NOTE:</b> app processes do not have the privilege to write system properties. You will
     * need to be the system or root user to set a system property.
     *
     * @throws IllegalArgumentException if the key exceeds 32 characters
     * @throws IllegalArgumentException if the value exceeds 92 characters
     */
    public static void set(String key, String val) {
        try {
            SP.getMethod("set", String.class, String.class).invoke(null, key, val);
        } catch (Exception ignored) {
        }
    }

    private static Class<?> getSystemPropertiesClass() {
        try {
            return Class.forName("android.os.SystemProperties");
        } catch (ClassNotFoundException shouldNotHappen) {
            return null;
        }
    }

}