docs: public char[] getCharBuffer(int expected) {
  		if (this.charBuffer.length >= expected) {
  			return charBuffer;
  		} else if (expected < MAX_SIZE) {
  			// ?预先设置多一点
  			this.charBuffer = new char[(int) (expected * 1.2)];
  		} else {
  			return EMPTY_CHAR_ARRAY;
  		}
  		return this.charBuffer;
  	}