java - 我可以使用不同类的静态方法吗？

Question

下面是我的 CuratorClient 类，它连接到 Zookeeper 并启动领导者选举过程。

public class CuratorClient {

    // can I make this as static?
    private static CuratorFramework client;
    private String latchPath;
    private String id;
    private LeaderLatch leaderLatch;

    public CuratorClient(String connString, String latchPath, String id) {
        client = CuratorFrameworkFactory.newClient(connString, new ExponentialBackoffRetry(1000, Integer.MAX_VALUE));
        this.id = id;
        this.latchPath = latchPath;
    }

    public void start() throws Exception {
        client.start();
        client.getCuratorClient().blockUntilConnectedOrTimedOut();
        leaderLatch = new LeaderLatch(client, latchPath, id);
        leaderLatch.start();
    }

    public boolean isLeader() {
        return leaderLatch.hasLeadership();
    }

    public Participant currentLeader() throws Exception {
        return leaderLatch.getLeader();
    }

    public void close() throws IOException {
        leaderLatch.close();
        client.close();
    }

    // can I use below method from any other class ?
    protected static List<String> getChildren(String node) throws Exception {
        return client.getChildren().forPath(node);
    }
}

当我的服务启动时，在静态 block 中，我将使用 CuratorClient 连接到 Zookeeper，并启动领导者选举过程。

public class TestService {

    private static CuratorClient curatorClient = null;
    static {

        try {
            String connectionString = "some-string";
            String hostname = "machineA";

            curatorClient = new CuratorClient(connectionString, "/my/latch", hostname);
            curatorClient.start();

        } catch (Exception ex) {
            // log exception
        }
    }

    ....
    ....

    // some method
    public Map<String, String> installNewSoftware(String node) {

    //.. some other code
    try {
        List<String> children = CuratorClient.getChildren("/my/example");
        System.out.println(children);

    } catch (Exception e) {
        e.printStackTrace();
    }

    //.. some other code
    return null;
    }
}

现在我还有一些其他类喜欢使用CuratorClient的getChildren方法，所以在这个类中，我可以像这样直接使用CuratorClient。 getChildren("/my/example"); 正确吗？

public class DifferentClass {

    ....
    ....

    // some new method
    public Map<String, String> installNewSoftware(String node) {
    try {
        List<String> children = CuratorClient.getChildren("/my/example");
        System.out.println(children);

    } catch (Exception e) {
        e.printStackTrace();
    }

    //.. some other code
    return null;
    }
}

总的来说，这不是馆长问题或动物园管理员问题。这基本上是一个设计问题，我想了解我这样做的方式是否会有任何问题？我假设 CuratorFramework 也将是线程安全的？

Answer 1

是的，您可以从其他类调用静态方法。

您的签名如下所示:

protected static List<String> getChildren(String node) throws Exception

您无法从另一个类调用它的原因是它是 protected (对当前类和子类可见)而不是公共(public)的(对任何地方都可见)。

如果使其可见，则可以使用 CuratorClient.getChildren() 调用它。

More information on access modifiers .
More information on class members (static fields) .