content: package com.ctrip.framework.apollo;
  
  import java.util.Date;
  import java.util.Locale;
  import java.util.Set;
  
  /**
   * @author Jason Song(song_s@ctrip.com)
   */
  public interface Config {
    /**
     * Return the property value with the given key, or {@code defaultValue} if the key doesn't exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value
     */
    public String getProperty(String key, String defaultValue);
  
    /**
     * Return the integer property value with the given key, or {@code defaultValue} if the key
     * doesn't exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as integer
     */
    public Integer getIntProperty(String key, Integer defaultValue);
  
    /**
     * Return the long property value with the given key, or {@code defaultValue} if the key doesn't
     * exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as long
     */
    public Long getLongProperty(String key, Long defaultValue);
  
    /**
     * Return the short property value with the given key, or {@code defaultValue} if the key doesn't
     * exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as short
     */
    public Short getShortProperty(String key, Short defaultValue);
  
    /**
     * Return the float property value with the given key, or {@code defaultValue} if the key doesn't
     * exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as float
     */
    public Float getFloatProperty(String key, Float defaultValue);
  
    /**
     * Return the double property value with the given key, or {@code defaultValue} if the key doesn't
     * exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as double
     */
    public Double getDoubleProperty(String key, Double defaultValue);
  
    /**
     * Return the byte property value with the given key, or {@code defaultValue} if the key doesn't
     * exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as byte
     */
    public Byte getByteProperty(String key, Byte defaultValue);
  
    /**
     * Return the boolean property value with the given key, or {@code defaultValue} if the key
     * doesn't exist.
     *
     * @param key          the property name
     * @param defaultValue the default value when key is not found or any error occurred
     * @return the property value as boolean
     */
    public Boolean getBooleanProperty(String key, Boolean defaultValue);
  
    /**
     * Return the array property value with the given key, or {@code defaultValue} if the key doesn't exist.
     *
     * @param key          the property name
     * @param delimiter    the delimiter regex
     * @param defaultValue the default value when key is not found or any error occurred
     */
    public String[] getArrayProperty(String key, String delimiter, String[] defaultValue);
  
    /**
     * Return the Date property value with the given name, or {@code defaultValue} if the name doesn't exist.
     * Will try to parse the date with Locale.US and formats as follows: yyyy-MM-dd HH:mm:ss.SSS,
     * yyyy-MM-dd HH:mm:ss and yyyy-MM-dd
     *
     * @param key          the property name
     * @param defaultValue the default value when name is not found or any error occurred
     * @return the property value
     */
    public Date getDateProperty(String key, Date defaultValue);
  
    /**
     * Return the Date property value with the given name, or {@code defaultValue} if the name doesn't exist.
     * Will parse the date with the format specified and Locale.US
     *
     * @param key          the property name
     * @param format       the date format, see {@link java.text.SimpleDateFormat} for more
     *                     information
     * @param defaultValue the default value when name is not found or any error occurred
     * @return the property value
     */
    public Date getDateProperty(String key, String format, Date defaultValue);
  
    /**
     * Return the Date property value with the given name, or {@code defaultValue} if the name doesn't exist.
     *
     * @param key          the property name
     * @param format       the date format, see {@link java.text.SimpleDateFormat} for more
     *                     information
     * @param locale       the locale to use
     * @param defaultValue the default value when name is not found or any error occurred
     * @return the property value
     */
    public Date getDateProperty(String key, String format, Locale locale, Date defaultValue);
  
    /**
     * Return the Enum property value with the given key, or {@code defaultValue} if the key doesn't exist.
     *
     * @param key          the property name
     * @param enumType     the enum class
     * @param defaultValue the default value when key is not found or any error occurred
     * @param <T>          the enum
     * @return the property value
     */
    public <T extends Enum<T>> T getEnumProperty(String key, Class<T> enumType, T defaultValue);
  
    /**
     * Return the duration property value(in milliseconds) with the given name, or {@code
     * defaultValue} if the name doesn't exist. Please note the format should comply with the follow
     * example (case insensitive). Examples:
     * <pre>
     *    "123MS"          -- parses as "123 milliseconds"
     *    "20S"            -- parses as "20 seconds"
     *    "15M"            -- parses as "15 minutes" (where a minute is 60 seconds)
     *    "10H"            -- parses as "10 hours" (where an hour is 3600 seconds)
     *    "2D"             -- parses as "2 days" (where a day is 24 hours or 86400 seconds)
     *    "2D3H4M5S123MS"  -- parses as "2 days, 3 hours, 4 minutes, 5 seconds and 123 milliseconds"
     * </pre>
     *
     * @param key          the property name
     * @param defaultValue the default value when name is not found or any error occurred
     * @return the parsed property value(in milliseconds)
     */
    public long getDurationProperty(String key, long defaultValue);
  
    /**
     * Add change listener to this config instance.
     *
     * @param listener the config change listener
     */
    public void addChangeListener(ConfigChangeListener listener);
  
    /**
     * Return a set of the property names
     *
     * @return the property names
     */
    public Set<String> getPropertyNames();
  }
  