Question

我正在学习使用HikariCP（我是java中的新手）并且我发现了一个包装器，但我认为它不是线程安全，而且单例的实例是线程安全但不是方法getConnection（）。课程是这样的：

public class HikariCPWrapper{
    private static final HikariCPWrapper INSTANCE;
    private HikariDataSource ds;
    static  
    {  
    INSTANCE = new HikariCPWrapper();    
    }  

    private HikariCPWrapper(){
        HikariConfig config = new HikariConfig(); 
        //config.set... 
        //... 
        ds = new HikariDataSource(config);  

    }

    public static HikariCPWrapper getInstance ()  
    {  
        return INSTANCE;  
    }  

    public Connection getConnection()  throws SQLException  
    {  
        return ds.getConnection();  
    }  
}

好吧，我需要向HikariConfig或HikariDataSource发送参数，所以我用这种方式重写：

public interface IConnectionProvider {
    void init(String jdbcUrl, String user, String password);
    Connection getConnection() throws SQLException;
}

    public class ConnectionProviderHikariCP implements IConnectionProvider{

    private static final ConnectionProviderHikariCP INSTANCE;
    private final HikariDataSource hikariDataSource;
    private Boolean initialized;
    //class initializer:
    static
    {
        INSTANCE = new ConnectionProviderHikariCP();
    }

    private ConnectionProviderHikariCP() {
        hikariDataSource = new HikariDataSource();
        initialized = false;
    }

    public static ConnectionProviderHikariCP getInstance() {
        return INSTANCE;
    }

    @Override
    public synchronized void init(String jdbcUrl, String user, String password) {
        hikariDataSource.setJdbcUrl(jdbcUrl);        
        hikariDataSource.setUsername(user);
        hikariDataSource.setPassword(password);
        initialized = true;
    }

    @Override
    public synchronized Connection getConnection() throws SQLException {
        if(!initialized)
           throw new UnsupportedOperationException("Debe inicializar mediante el método Init() primero!!!!!."); 

        return hikariDataSource.getConnection();
    }

}

我这样使用它：

IConnectionProvider connectionProvider = ConnectionProviderHikariCP.getInstance();
connectionProvider.init(url, user, passwd);

BaseDAOFactory fatory = new MySqlDAOFactory(connectionProvider);
IExerciseBO exerciseBO = new ExerciseBO(fatory);

但我没有java经验，所以我需要你的建议。是头等（原始）线程安全吗？我的实现线程安全吗？

Answer 1

HikariCP本身是线程安全的。据我了解，您尝试做的是在通过getConnection()方法初始化HikariDataSource之前阻止来电者init()。据推测，您还希望阻止多次调用init()数据源。

对于池吞吐量，一般来说，使用synchronized来包装getConnection()是个坏主意。根据您的上述代码，我推荐以下模式：

public class ConnectionProviderHikariCP implements IConnectionProvider {

  private static final ConnectionProviderHikariCP INSTANCE;
  private final HikariDataSource hikariDataSource;
  private AtomicBoolean initialized;
  //class initializer:
  static
  {
     INSTANCE = new ConnectionProviderHikariCP();
  }

  private ConnectionProviderHikariCP() {
     hikariDataSource = new HikariDataSource();
     initialized = new AtomicInteger();
  }

  public static ConnectionProviderHikariCP getInstance() {
     return INSTANCE;
  }

  @Override
  public void init(String jdbcUrl, String user, String password) {
     if (initialized.compareAndSet(false, true)) {
        hikariDataSource.setJdbcUrl(jdbcUrl);        
        hikariDataSource.setUsername(user);
        hikariDataSource.setPassword(password);
     }
     else {
        throw new IllegalStateException("Connection provider already initialized.");
     }
  }

  @Override
  public Connection getConnection() throws SQLException {
     if (initialized.get()) {
        return hikariDataSource.getConnection();
     }

     throw new UnsupportedOperationException("Debe inicializar mediante el método Init() primero!!!!!."); 
  }
}

HikariCP Wrapper（线程安全）

1 个答案: