在得到评论和更好地理解TLS协议之后，我可以通过实现缓冲区并获得TLS记录的确切大小来等待其他TCP读取来找到问题的解决方案。
一个TLS记录“可能被分割成多个TCP片段，或者TCP片段也可能包含多个完整的、一半的或其他的TLS记录。这些TCP片段甚至可能被分割成多个IP数据包，尽管TCP努力避免这种情况。"，来自Determine packet size of TLS packet Java/Android。然而，该帖子提到了前2个字节，这是不正确的。根据https://hpbn.co/transport-layer-security-tls/#tls-record-diagram:
最大TLS记录大小为16 KB

每条记录包含一个5字节的报头、一个MAC（SSLv3、TLS 1.0、TLS 1.1最多20字节，TLS 1.2最多32字节）和填充（如果使用块密码）。
要解密和验证记录，必须提供整个记录。

TLS记录大小取决于第3和第4字节：

代码最后是这样的：

protected synchronized void read(SocketChannel socketChannel, SSLEngine engine) throws IOException {

    this.peerNetData.clear();
    int bytesRead = socketChannel.read(this.peerNetData);
    if (bytesRead > 0) {
        // TLS records buffering
        this.peerNetData.flip();
        byte[] justRead = new byte[this.peerNetData.limit()];
        this.peerNetData.get(justRead);
        this.tlsRecordsReadBuffer.put(justRead);
        byte[] fullTlsRecord;

        // Process every TLS record available until buffer is empty or the last record is yet not complete
        while ( (fullTlsRecord = this.getFullTlsRecordFromBufferAndDeleteIt()) != null ) {
                this.peerNetData.clear();
                this.peerNetData.put(fullTlsRecord);
                handleEncryptedTransaction(socketChannel, engine);
        }
    } else if (bytesRead < 0) {
        handleEndOfStream(socketChannel, engine);
    }
}

private synchronized byte[] getFullTlsRecordFromBufferAndDeleteIt() {
    byte[] result = null;
    this.tlsRecordsReadBuffer.flip();

    if (this.tlsRecordsReadBuffer.limit() > DEFAULT_TLS_HEADER_SIZE) {
        // Read only the first 5 bytes (5 = DEFAULT_TLS_HEADER_SIZE) which contains TLS record length
        byte[] tlsHeader = new byte[DEFAULT_TLS_HEADER_SIZE];
        this.tlsRecordsReadBuffer.get(tlsHeader);

        **// read 3rd and 4th bytes to get TLS record length in big endian notation
        int tlsRecordSize = ((tlsHeader[3] & 0xff) << 8) | (tlsHeader[4] & 0xff);**
        // 0xff IS NECESSARY because it removes one-bit negative representation
        // Set  position back to the beginning
        this.tlsRecordsReadBuffer.position(0);
        if (this.tlsRecordsReadBuffer.limit() >= (tlsRecordSize + DEFAULT_TLS_HEADER_SIZE)) {
            // Then we have a complete TLS record
            result = new byte[tlsRecordSize + DEFAULT_TLS_HEADER_SIZE];
            this.tlsRecordsReadBuffer.get(result);
        }
    }

    // remove record and get back to write mode
    this.tlsRecordsReadBuffer.compact();
    return result;
}