接收数据不完整丢失了 about serialport HOT 9 CLOSED

public HeadStickPackageHelper(byte[] head) {
    this.head = head;
    if (head == null) {
        throw new IllegalStateException(" head or tail ==null");
    }
    if (head.length == 0) {
        throw new IllegalStateException(" head and tail length==0");
    }
    headLen = head.length;
    bytes = new ArrayList<>();
}

private boolean endWith(Byte[] src, byte[] target) {
    if (src.length < target.length) {
        return false;
    }
    for (int i = 0; i < target.length; i++) {
        if (target[target.length - i - 1] != src[src.length - i - 1]) {
            return false;
        }
    }
    return true;
}

private byte[] getRangeBytes(List<Byte> list, int start, int end) {
    Byte[] temps = Arrays.copyOfRange(list.toArray(new Byte[0]), start, end);
    byte[] result = new byte[temps.length];
    for (int i = 0; i < result.length; i++) {
        result[i] = temps[i];
    }
    return result;
}

@Override
public byte[] execute(InputStream is) {
    bytes.clear();
    int len = -1;
    byte temp;
    int startIndex = -1;
    byte[] result = null;
    boolean isFindStart = false;
    try {
        while ((len = is.read()) != -1) {
            temp = (byte) len;
            bytes.add(temp);
            Byte[] byteArray = bytes.toArray(new Byte[]{});
            if (headLen == 0) {//Only head or tail markers
                if (endWith(byteArray, head)) {
                    if (startIndex == -1) {
                        startIndex = bytes.size() - headLen;
                    } else {
                        result = getRangeBytes(bytes, startIndex, bytes.size());
                        break;
                    }
                }
            } else {
                if (!isFindStart) {
                    if (endWith(byteArray, head)) {
                        startIndex = bytes.size() - headLen;
                        isFindStart = true;
                    }
                } else {
                    //5代表你的数据长度，自己修改
                    if (startIndex + headLen <= bytes.size()-5) {
                        result = getRangeBytes(bytes, startIndex, bytes.size());
                        break;
                    }
                }
            }
        }
        if (len == -1) {
            return null;
        }
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
    return result;
}