code: public static String replace(String pattern, Context context) {
          if (null == pattern)
              return null;
          if (null == context)
              return pattern;
          return replace(new CharSegment(pattern), context);
      }
docs: 根据字符串片段，将上下文对象替换对应占位符。未赋值的占位符维持原样
  
  @param pattern
  字符串片段
  @param context
  上下文对象
  @return 替换后的字符串