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作者:Albert.Wen  添加时间:2020-01-28 17:16:35  修改时间:2024-03-24 14:37:29  分类:Java基础  编辑

从 JFinal 框架中,抽取出一个 读取 .properties 配置文件的助手类 PropHelper.java

使用示例:

PropHelper.use("config.txt", "UTF-8");
PropHelper.use("other_config.txt", "UTF-8");
String userName = PropHelper.get("userName");
String password = PropHelper.get("password");

userName = PropHelper.use("other_config.txt").get("userName");
password = PropHelper.use("other_config.txt").get("password");

PropHelper.use("wen/jianbao/config_in_sub_directory_of_classpath.txt");

1、文件 Prop.java

package wen.jianbao.helper;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.util.Properties;

/**
 * Prop. Prop can load properties file from CLASSPATH or File object.
 */
public class Prop {
    
    protected Properties properties;
    private static final Logger logger = LoggerFactory.getLogger(Prop.class);

    /**
     * 支持 new Prop().appendIfExists(...)
     */
    public Prop() {
        properties = new Properties();
    }

    /**
     * Prop constructor.
     *
     * @see #Prop(String, String)
     */
    public Prop(String fileName) {
        this(fileName, "UTF-8");
    }

    /**
     * Prop constructor
     * <p>
     * Example:<br>
     * Prop prop = new Prop("my_config.txt", "UTF-8");<br>
     * String userName = prop.get("userName");<br><br>
     * <p>
     * prop = new Prop("com/dudubashi/file_in_sub_path_of_classpath.txt", "UTF-8");<br>
     * String value = prop.get("key");
     *
     * @param fileName the properties file's name in classpath or the sub directory of classpath
     * @param encoding the encoding
     */
    public Prop(String fileName, String encoding) {
        InputStream inputStream = null;
        try {
            inputStream = getClassLoader().getResourceAsStream(fileName);        // properties.load(Prop.class.getResourceAsStream(fileName));
            if (inputStream == null) {
                throw new IllegalArgumentException("Properties file not found in classpath: " + fileName);
            }
            properties = new Properties();
            properties.load(new InputStreamReader(inputStream, encoding));
        } catch (IOException e) {
            throw new RuntimeException("Error loading properties file.", e);
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    logger.error(e.getMessage(), e);
                }
            }
        }
    }

    private ClassLoader getClassLoader() {
        ClassLoader ret = Thread.currentThread().getContextClassLoader();
        return ret != null ? ret : getClass().getClassLoader();
    }

    /**
     * Prop constructor.
     *
     * @see #Prop(File, String)
     */
    public Prop(File file) {
        this(file, "UTF-8");
    }

    /**
     * Prop constructor
     * <p>
     * Example:<br>
     * Prop prop = new Prop(new File("/var/config/my_config.txt"), "UTF-8");<br>
     * String userName = prop.get("userName");
     *
     * @param file     the properties File object
     * @param encoding the encoding
     */
    public Prop(File file, String encoding) {
        if (file == null) {
            throw new IllegalArgumentException("File can not be null.");
        }
        if (!file.isFile()) {
            throw new IllegalArgumentException("File not found : " + file.getName());
        }

        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(file);
            properties = new Properties();
            properties.load(new InputStreamReader(inputStream, encoding));
        } catch (IOException e) {
            throw new RuntimeException("Error loading properties file.", e);
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    logger.error(e.getMessage(), e);
                }
            }
        }
    }

    public Prop append(Prop prop) {
        if (prop == null) {
            throw new IllegalArgumentException("prop can not be null");
        }
        properties.putAll(prop.getProperties());
        return this;
    }

    public Prop append(String fileName, String encoding) {
        return append(new Prop(fileName, encoding));
    }

    public Prop append(String fileName) {
        return append(fileName, "UTF-8");
    }

    public Prop appendIfExists(String fileName, String encoding) {
        try {
            return append(new Prop(fileName, encoding));
        } catch (Exception e) {
            return this;
        }
    }

    public Prop appendIfExists(String fileName) {
        return appendIfExists(fileName, "UTF-8");
    }

    public Prop append(File file, String encoding) {
        return append(new Prop(file, encoding));
    }

    public Prop append(File file) {
        return append(file, "UTF-8");
    }

    public Prop appendIfExists(File file, String encoding) {
        if (file.isFile()) {
            append(new Prop(file, encoding));
        }
        return this;
    }

    public Prop appendIfExists(File file) {
        return appendIfExists(file, "UTF-8");
    }

    public String get(String key) {
        return properties.getProperty(key);
    }

    public String get(String key, String defaultValue) {
        return properties.getProperty(key, defaultValue);
    }

    public Integer getInt(String key) {
        return getInt(key, null);
    }

    public Integer getInt(String key, Integer defaultValue) {
        String value = properties.getProperty(key);
        if (value != null) {
            return Integer.parseInt(value.trim());
        }
        return defaultValue;
    }

    public Long getLong(String key) {
        return getLong(key, null);
    }

    public Long getLong(String key, Long defaultValue) {
        String value = properties.getProperty(key);
        if (value != null) {
            return Long.parseLong(value.trim());
        }
        return defaultValue;
    }

    public Boolean getBoolean(String key) {
        return getBoolean(key, null);
    }

    public Boolean getBoolean(String key, Boolean defaultValue) {
        String value = properties.getProperty(key);
        if (value != null) {
            value = value.toLowerCase().trim();
            if ("true".equals(value)) {
                return true;
            } else if ("false".equals(value)) {
                return false;
            }
            throw new RuntimeException("The value can not parse to Boolean : " + value);
        }
        return defaultValue;
    }

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

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

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

    public Properties getProperties() {
        return properties;
    }
}

2、文件 PropHelper.java

package wen.jianbao.helper;

import java.io.File;
import java.util.concurrent.ConcurrentHashMap;

/**
 * PropHelper. PropHelper can load properties file from CLASSPATH or File object.
 */
public class PropHelper {

    private static Prop prop = null;
    private static final ConcurrentHashMap<String, Prop> map = new ConcurrentHashMap<>();

    private PropHelper() {
    }

    /**
     * Use the first found properties file
     */
    public static Prop useFirstFound(String... fileNames) {
        for (String fn : fileNames) {
            try {
                return use(fn, "UTF-8");
            } catch (Exception e) {
                continue;
            }
        }

        throw new IllegalArgumentException("没有配置文件可被使用");
    }

    /**
     * Use the properties file. It will loading the properties file if not loading.
     *
     * @see #use(String, String)
     */
    public static Prop use(String fileName) {
        return use(fileName, "UTF-8");
    }

    /**
     * Use the properties file. It will loading the properties file if not loading.
     * <p>
     * Example:<br>
     * PropHelper.use("config.txt", "UTF-8");<br>
     * PropHelper.use("other_config.txt", "UTF-8");<br><br>
     * String userName = PropHelper.get("userName");<br>
     * String password = PropHelper.get("password");<br><br>
     * <p>
     * userName = PropHelper.use("other_config.txt").get("userName");<br>
     * password = PropHelper.use("other_config.txt").get("password");<br><br>
     * <p>
     * PropHelper.use("com/dudubashi/config_in_sub_directory_of_classpath.txt");
     *
     * @param fileName the properties file's name in classpath or the sub directory of classpath
     * @param encoding the encoding
     */
    public static Prop use(String fileName, String encoding) {
        Prop result = map.get(fileName);
        if (result == null) {
            synchronized (PropHelper.class) {
                result = map.get(fileName);
                if (result == null) {
                    result = new Prop(fileName, encoding);
                    map.put(fileName, result);
                    if (PropHelper.prop == null) {
                        PropHelper.prop = result;
                    }
                }
            }
        }
        return result;
    }

    /**
     * Use the properties file bye File object. It will loading the properties file if not loading.
     *
     * @see #use(File, String)
     */
    public static Prop use(File file) {
        return use(file, "UTF-8");
    }

    /**
     * Use the properties file bye File object. It will loading the properties file if not loading.
     * <p>
     * Example:<br>
     * PropHelper.use(new File("/var/config/my_config.txt"), "UTF-8");<br>
     * Strig userName = PropHelper.use("my_config.txt").get("userName");
     *
     * @param file     the properties File object
     * @param encoding the encoding
     */
    public static Prop use(File file, String encoding) {
        Prop result = map.get(file.getName());
        if (result == null) {
            synchronized (PropHelper.class) {
                result = map.get(file.getName());
                if (result == null) {
                    result = new Prop(file, encoding);
                    map.put(file.getName(), result);
                    if (PropHelper.prop == null) {
                        PropHelper.prop = result;
                    }
                }
            }
        }
        return result;
    }

    public static Prop useless(String fileName) {
        Prop previous = map.remove(fileName);
        if (PropHelper.prop == previous) {
            PropHelper.prop = null;
        }
        return previous;
    }

    public static void clear() {
        prop = null;
        map.clear();
    }

    public static Prop append(Prop prop) {
        synchronized (PropHelper.class) {
            if (PropHelper.prop != null) {
                PropHelper.prop.append(prop);
            } else {
                PropHelper.prop = prop;
            }
            return PropHelper.prop;
        }
    }

    public static Prop append(String fileName, String encoding) {
        return append(new Prop(fileName, encoding));
    }

    public static Prop append(String fileName) {
        return append(fileName, "UTF-8");
    }

    public static Prop appendIfExists(String fileName, String encoding) {
        try {
            return append(new Prop(fileName, encoding));
        } catch (Exception e) {
            return PropHelper.prop;
        }
    }

    public static Prop appendIfExists(String fileName) {
        return appendIfExists(fileName, "UTF-8");
    }

    public static Prop append(File file, String encoding) {
        return append(new Prop(file, encoding));
    }

    public static Prop append(File file) {
        return append(file, "UTF-8");
    }

    public static Prop appendIfExists(File file, String encoding) {
        if (file.exists()) {
            append(new Prop(file, encoding));
        }
        return PropHelper.prop;
    }

    public static Prop appendIfExists(File file) {
        return appendIfExists(file, "UTF-8");
    }

    public static Prop getProp() {
        if (prop == null) {
            throw new IllegalStateException("Load propties file by invoking PropHelper.use(String fileName) method first.");
        }
        return prop;
    }

    public static Prop getProp(String fileName) {
        return map.get(fileName);
    }

    public static String get(String key) {
        return getProp().get(key);
    }

    public static String get(String key, String defaultValue) {
        return getProp().get(key, defaultValue);
    }

    public static Integer getInt(String key) {
        return getProp().getInt(key);
    }

    public static Integer getInt(String key, Integer defaultValue) {
        return getProp().getInt(key, defaultValue);
    }

    public static Long getLong(String key) {
        return getProp().getLong(key);
    }

    public static Long getLong(String key, Long defaultValue) {
        return getProp().getLong(key, defaultValue);
    }

    public static Boolean getBoolean(String key) {
        return getProp().getBoolean(key);
    }

    public static Boolean getBoolean(String key, Boolean defaultValue) {
        return getProp().getBoolean(key, defaultValue);
    }

    public static boolean containsKey(String key) {
        return getProp().containsKey(key);
    }
}