java调用approve 授权

设置gas和limit 小了后然后一直等待直到超时然后报错 org.web3j.protocol.exceptions.TransactionException: Transaction receipt was not generated after 600 seconds for transaction: 试着把gas和limit 设置大后报这个：exceeds block gas limit 应该怎么设置呢？是设置gas错误？还是说approve是这个方法有问题呢？求大佬解决。

    //网上教程让设置默认得，好像也不好用
     BigInteger GAS = Contract.GAS_LIMIT;
     BigInteger GAS_PRICE = Contract.GAS_PRICE;

   //手动指定也不行
    BigInteger limit = new BigInteger("8000000");

    TokenERC20 contract = TokenERC20.load(contractAddress, web3j, credentials,
            GAS_PRICE,GAS);

    RemoteCall<TransactionReceipt> remoteCall=  contract.approve("被授权地址",new BigInteger("授权数量"));
    TransactionReceipt receipt = remoteCall.send();

    // 封装
    public RemoteCall<TransactionReceipt> approve(String _spender, BigInteger _value) {
    Function function = new Function(
            "approve",
            Arrays.<Type>asList(new Address(_spender),
                    new Uint256(_value)),
            Collections.<TypeReference<?>>emptyList());
    return executeRemoteCallTransaction(function);
}