Postgres中的COPY FROM和C3PO连接池

Question

我的JAVA程序中有以下代码,允许我将文件中的数据复制到Postgres数据库中:

Connection con = DriverManager.getConnection("jdbc:postgresql://localhost:####/myDb", 
                                                   "myuser", "mypassword"); 
CopyManager cm = new CopyManager((BaseConnection) con);
cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", 
             new BufferedReader(new FileReader(filepath)), buffersize);

这段代码工作正常,但我想使用连接池来管理我的连接,因为我有这个代码运行多个文件.所以我使用了C3P0.

public static final ComboPooledDataSource cpds = new ComboPooledDataSource();

public class MyPooledConnection {
MyPooledConnection() throws PropertyVetoException {
    cpds.setDriverClass("org.postgresql.Driver"); 
    cpds.setJdbcUrl("jdbc:postgresql://localhost:5432/myStockDatabase"); 
    cpds.setUser("myUserName"); 
    cpds.setPassword("myPassword"); 
    cpds.setInitialPoolSize(4);
    cpds.setMinPoolSize(4);
    cpds.setMaxIdleTime(30);
    cpds.setMaxPoolSize(MAX_CONNECTIONS);
}

public static Connection getConnection() {
    return cpds.getConnection();
}
}

但是,当我从上面的连接池获得连接并尝试使用CopyManager时,如下例所示,代码不起作用

Connection pooled_con = MyPooledConnection.getConnection();
CopyManager cm = new CopyManager((BaseConnection) pooled_con);
cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", 
             new BufferedReader(new FileReader(filepath)), buffersize);

我猜这个问题与连接有关,但我似乎无法弄清楚它有什么不同.我尝试用SQLException和IOException捕获错误,但它也没有捕获.有没有遇到过这个？

---- 更新 ----

感谢a_horse_with_no_name对此的指导.以下代码对我有用

// Cast the connection as a proxy connection
C3P0ProxyConnection proxycon = (C3P0ProxyConnection)cpds.getConnection();
try {

    // Pass the getCopyAPI (from PGConnection) to a method
    Method m = PGConnection.class.getMethod("getCopyAPI", new Class[]{});
    Object[] arg = new Object[] {};

    // Call rawConnectionOperation, passing the method, the raw_connection, 
    // and method parameters, and then cast as CopyManager
    CopyManager cm = (CopyManager) proxycon.rawConnectionOperation(m,
                                         C3P0ProxyConnection.RAW_CONNECTION,arg);
    cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", new BufferedReader(new 
                                                FileReader(filepath)), buffersize);
} catch (NoSuchMethodException | IllegalAccessException 
                        | IllegalArgumentException | InvocationTargetException e) {
    // Deal with errors here
}

Answer 1

该池不会为您提供“本机”连接，它总是分发一个代理对象：

从手册中：

C3P0 将这些对象包装在代理后面，因此您无法将 C3P0 返回的连接或语句转换为特定于供应商的实现类

您可能无法使用 C3P0 使用 CopyManager。我不确定，但也许您可以使用此处描述的解决方法：http ://www.mchange.com/projects/c3p0/#raw_connection_ops

如果这不起作用，您可能需要使用不同的连接池（例如新的Tomcat 7 JDBC-Pool）来访问底层本机连接。