Question

我正在使用Oracle 11g XE和java 8.我正在开发桌面应用程序并希望进行连接池。应用程序在执行pds.getConnection（）时挂起;我尝试使用简单的JDBC，工作正常，因此它不是网络/数据库问题。这是我要调用的代码 -

/**
 * This returns DB connection from the DB Connection Pool
 * 
 * @return
 * @throws IOException
 * @throws SQLException
 */
public static Connection getConnection() throws IOException, SQLException {
    if (pds == null) {
        initConnectionPool();
    }
    Connection conn = pds.getConnection();
    System.out.println("Available connections after checkout: " + pds.getAvailableConnectionsCount());
    System.out.println("Borrowed connections after checkout: " + pds.getBorrowedConnectionsCount());
    return conn;
}


/**
 * init DB Connection Pool
 * 
 * @return
 * @throws IOException
 * @throws SQLException
 */
private static void initConnectionPool() throws IOException, SQLException {
    Properties configProperties = Utils.getConfig();

    // Get the PoolDataSource for UCP
    PoolDataSource pds = PoolDataSourceFactory.getPoolDataSource();

    // Set the connection factory first before all other properties
    System.out.println("Class name :" + configProperties.getProperty("CONNECTION_FACTORY_CLASS_NAME"));
    pds.setConnectionFactoryClassName(configProperties.getProperty("CONNECTION_FACTORY_CLASS_NAME"));

    System.out.println("DB URL ==" + configProperties.getProperty("DB_URL"));
    pds.setURL(configProperties.getProperty("DB_URL"));

    System.out.println("DB User ==" + configProperties.getProperty("DB_USER"));
    pds.setUser(configProperties.getProperty("DB_USER"));

    System.out.println("Password==" + configProperties.getProperty("DB_PSWD"));
    pds.setPassword(configProperties.getProperty("DB_PSWD"));

    pds.setConnectionPoolName("JDBC_UCP_POOL");

    // Default is 0. Set the initial number of connections to be created
    // when UCP is started.
    pds.setInitialPoolSize(Integer.parseInt(configProperties.getProperty("INITIAL_POOL_SIZE")));

    // Default is 0. Set the minimum number of connections
    // that is maintained by UCP at runtime.
    pds.setMinPoolSize(Integer.parseInt(configProperties.getProperty("MIN_POOL_SIZE")));

    // Default is Integer.MAX_VALUE (2147483647). Set the maximum number of
    // connections allowed on the connection pool.
    pds.setMaxPoolSize(Integer.parseInt(configProperties.getProperty("MAX_POOL_SIZE")));
}



/**
 * Loads the config file and return instance of Properties
 * 
 * @return Proterties
 * @throws IOException
 */

public static Properties getConfig() throws IOException {

    if (configProps != null)
        return configProps;
    configProps = new Properties();
    FileInputStream in;
    in = new FileInputStream("bin/resources/config.properties");
    configProps.load(in);
    in.close();
    return configProps;
}

使用的属性是 -

DB_URL = JDBC：预言：瘦：@ //本地主机：1521 / XE

INITIAL_POOL_SIZE = 5

MIN_POOL_SIZE = 5

MAX_POOL_SIZE = 10

CONNECTION_FACTORY_CLASS_NAME = oracle.jdbc.pool.OracleDataSource

Answer 1

您没有初始化pds类变量。致电getConnection()时，始终为null。

确保在使用静态初始化程序块后调用初始化池的方法。

static { initConnectionPool（）; }

Answer 2

我发现了错误。在initialize（）中，我声明了一个局部变量pds。我删除了它，让类变量初始化，代码开始工作。我很惊讶为什么在这种情况下我没有得到NullPointerException。这可以节省很多时间。

poolDataSource.getConnection（）挂起。尝试使用ojdbc6和ojdbc8 jar

2 个答案: