Question

我想使用以下代码连接到我的本地cassandra数据库：

public class StartDriver {
public static void main(String[] args) {

    Cluster cluster = null;
    try {
        cluster = Cluster.builder() // (1)
                .addContactPoint("127.0.0.1").withPort(9042).build();
        SocketOptions socketOptions = cluster.getConfiguration().getSocketOptions();
        socketOptions.setConnectTimeoutMillis(1000);

        System.out.println("Connection established");
        Session session = cluster.connect(); // (2)
        System.out.println(session.getState().getConnectedHosts());
        System.out.println("Try to execute Query");
        ResultSet rs = session.execute("SELECT * FROM htw.student");
        System.out.println("Query executed");// (3)
        Row row = rs.one();

    //  System.out.println(row.getString("release_version"));
        if (cluster != null) cluster.close();
    } catch (Exception e) {
        e.printStackTrace();
    }

}

}

可以建立连接，但是在session.execute（），程序永远挂起，没有任何错误消息。我在windows下使用Cassandra 3.8.0。通过cqlsh和devCenter连接是可能的，并且工作得很好。有人可以帮忙吗？在cassandra.yaml中是否有任何配置需要改变？

我得到的输出如下：

 SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Connection established
[/127.0.0.1:9042]
Try to execute Query

Answer 1

运行此代码，请告诉我您的输出。

public class StartDriver {
public static void main(String[] args) {

Cluster cluster = null;
try {
    cluster = Cluster.builder() // (1)
            .addContactPoint("127.0.0.1").withPort(9042).build();
    SocketOptions socketOptions = cluster.getConfiguration().getSocketOptions();
    socketOptions.setConnectTimeoutMillis(1000);

    System.out.println("Connection established");
    Session session = cluster.connect(); // (2)
    System.out.println(session.getState().getConnectedHosts());
    System.out.println("Try to execute Query");
    ResultSet rs = session.execute("SELECT count(*) FROM htw.student");
    System.out.println("Query executed");// (3)
    Row row = rs.one();

    System.out.println(row.getLong("count"));
    if (cluster != null) cluster.close();
} catch (Exception e) {
    e.printStackTrace();
}

}

Answer 2

问题是在类路径中有一些lib就像guava，它们来自cassandra-driver-core。我将projekt转换为maven projekt，从这一点来看，lib似乎相互阻碍。我从libs文件夹中删除了lib'，只使用了maven depnendencies，而不是像魅力一样的wirking。

Cassandra Connection Session.execute无限地阻塞

2 个答案: