【属性值的各种数据类型转换】

 

 

前提条件，先构造一个properties文件

 

Properties properties = new Properties();

// 使用ClassLoader加载properties配置文件生成对应的输入流

InputStream in = PropertiesMain.class.getClassLoader().getResourceAsStream("config/config.properties");

// 使用properties对象加载输入流 ,注意最后释放资源关闭文件流

properties.load(in);

 

 

 

代码详解

/**
 * get property value
 *
 * @param key property name
 * @return property value
 */
public static String getString(String key) {
    return properties.getProperty(key.trim());
}

/**
 * get property value with upper case
 *
 * @param key property name
 * @return property value  with upper case
 */
public static String getUpperCaseString(String key) {
    return properties.getProperty(key.trim()).toUpperCase();
}

/**
 * get property value
 *
 * @param key property name
 * @param defaultVal default value
 * @return property value
 */
public static String getString(String key, String defaultVal) {
    String val = properties.getProperty(key.trim());
    return val == null ? defaultVal : val;
}

/**
 * get property value
 *
 * @param key property name
 * @return  get property int value , if key == null, then return -1
 */
public static int getInt(String key) {
    return getInt(key, -1);
}

/**
 *
 * @param key key
 * @param defaultValue default value
 * @return property value
 */
public static int getInt(String key, int defaultValue) {
    String value = getString(key);
    if (value == null) {
        return defaultValue;
    }

    try {
        return Integer.parseInt(value);
    } catch (NumberFormatException e) {
        logger.info(e.getMessage(),e);
    }
    return defaultValue;
}

/**
 * get property value
 *
 * @param key property name
 * @return property value
 */
public static boolean getBoolean(String key) {
    String value = properties.getProperty(key.trim());
    if(null != value){
        return Boolean.parseBoolean(value);
    }

    return false;
}

/**
 * get property value
 *
 * @param key property name
 * @param defaultValue default value
 * @return property value
 */
public static Boolean getBoolean(String key, boolean defaultValue) {
    String value = properties.getProperty(key.trim());
    if(null != value){
        return Boolean.parseBoolean(value);
    }

    return defaultValue;
}

/**
 * get property long value
 * @param key key
 * @param defaultVal default value
 * @return property value
 */
public static long getLong(String key, long defaultVal) {
    String val = getString(key);
    return val == null ? defaultVal : Long.parseLong(val);
}

/**
 *
 * @param key key
 * @return property value
 */
public static long getLong(String key) {
    return getLong(key,-1);
}

/**
 *
 * @param key key
 * @param defaultVal default value
 * @return property value
 */
public double getDouble(String key, double defaultVal) {
    String val = getString(key);
    return val == null ? defaultVal : Double.parseDouble(val);
}


/**
 *  get array
 * @param key       property name
 * @param splitStr  separator
 * @return property value through array
 */
public static String[] getArray(String key, String splitStr) {
    String value = getString(key);
    if (value == null) {
        return new String[0];
    }
    try {
        String[] propertyArray = value.split(splitStr);
        return propertyArray;
    } catch (NumberFormatException e) {
        logger.info(e.getMessage(),e);
    }
    return new String[0];
}

/**
 *
 * @param key key
 * @param type type
 * @param defaultValue default value
 * @param <T> T
 * @return  get enum value
 */
public <T extends Enum<T>> T getEnum(String key, Class<T> type,
                                     T defaultValue) {
    String val = getString(key);
    return val == null ? defaultValue : Enum.valueOf(type, val);
}

/**
 * get all properties with specified prefix, like: fs.
 * @param prefix prefix to search
 * @return all properties with specified prefix
 */
public static Map<String, String> getPrefixedProperties(String prefix) {
    Map<String, String> matchedProperties = new HashMap<>();
    for (String propName : properties.stringPropertyNames()) {
        if (propName.startsWith(prefix)) {
            matchedProperties.put(propName, properties.getProperty(propName));
        }
    }
    return matchedProperties;
}

代码来自dolphinscheduler的1.36版本