Web3j 获取区块 ID - 使用时间戳高效查找

要根据时间戳获得块id，可以使用以下代码：

public static BigInteger getBlockIdByTimestamp(Web3j web3j, long timestamp) throws Exception {
    BigInteger latestBlockNumber = web3j.ethBlockNumber().send().getBlockNumber();
    BigInteger earliestBlockNumber = BigInteger.ZERO;

    while (latestBlockNumber.compareTo(earliestBlockNumber) >= 0) {
        BigInteger midBlockNumber = latestBlockNumber.add(earliestBlockNumber).divide(BigInteger.valueOf(2));
        EthBlock midBlock = web3j.ethGetBlockByNumber(DefaultBlockParameter.valueOf(midBlockNumber), true).send();

        if (midBlock.getBlock() != null && midBlock.getBlock().getTimestamp().longValue() >= timestamp) {
            // 优化：根据时间差计算减多少
            long timeDifference = midBlock.getBlock().getTimestamp().longValue() - timestamp;
            latestBlockNumber = midBlockNumber.subtract(BigInteger.valueOf(timeDifference / 3000 + 1)); // 每个块ID大约3秒，所以除以3000并加1
        } else {
            earliestBlockNumber = midBlockNumber.add(BigInteger.ONE);
        }
    }

    // 检查最早的块是否在时间范围内
    EthBlock earliestBlock = web3j.ethGetBlockByNumber(DefaultBlockParameter.valueOf(earliestBlockNumber), true).send();
    if (earliestBlock.getBlock() != null && earliestBlock.getBlock().getTimestamp().longValue() >= timestamp) {
        return earliestBlock.getBlock().getNumber();
    }

    return null;
}

这个方法使用二分查找来找到最接近给定时间戳的块。首先，它获取当前最新的块号和初始块号（0）。然后，它在这个范围内进行二分查找，直到找到最接近时间戳的块。最后，它检查找到的块是否在时间范围内，并返回块号。

为了满足每隔三秒产生一个块id的条件，可以在循环中加入等待时间的逻辑。代码如下：

public static BigInteger getBlockIdByTimestamp(Web3j web3j, long timestamp) throws Exception {
    BigInteger latestBlockNumber = web3j.ethBlockNumber().send().getBlockNumber();
    BigInteger earliestBlockNumber = BigInteger.ZERO;

    while (latestBlockNumber.compareTo(earliestBlockNumber) >= 0) {
        BigInteger midBlockNumber = latestBlockNumber.add(earliestBlockNumber).divide(BigInteger.valueOf(2));
        EthBlock midBlock = web3j.ethGetBlockByNumber(DefaultBlockParameter.valueOf(midBlockNumber), true).send();

        if (midBlock.getBlock() != null && midBlock.getBlock().getTimestamp().longValue() >= timestamp) {
            // 优化：根据时间差计算减多少
            long timeDifference = midBlock.getBlock().getTimestamp().longValue() - timestamp;
            latestBlockNumber = midBlockNumber.subtract(BigInteger.valueOf(timeDifference / 3000 + 1)); // 每个块ID大约3秒，所以除以3000并加1
        } else {
            earliestBlockNumber = midBlockNumber.add(BigInteger.ONE);
        }

        // 等待 3 秒
        Thread.sleep(3000);
    }

    // 检查最早的块是否在时间范围内
    EthBlock earliestBlock = web3j.ethGetBlockByNumber(DefaultBlockParameter.valueOf(earliestBlockNumber), true).send();
    if (earliestBlock.getBlock() != null && earliestBlock.getBlock().getTimestamp().longValue() >= timestamp) {
        return earliestBlock.getBlock().getNumber();
    }

    return null;
}

这个方法每次循环结束后会等待3秒钟，以满足每隔三秒产生一个块id的条件。