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);
此代码工作正常,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将其与CopyManager一起使用时,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。有没有人遇到过这个?
---- 的修订版 ----
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
}
答案 0 :(得分:4)
游泳池没有给你"本地"连接,它总是发出一个代理对象:
从手册:
C3P0将这些对象包装在代理之后,因此您无法将C3P0返回的连接或语句强制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,但也许你可以使用这里描述的解决方法:http://www.mchange.com/projects/c3p0/#raw_connection_ops
如果这不起作用,您可能希望使用不同的连接池(例如新的Tomcat 7 JDBC-Pool),以便您访问基础本机连接。
答案 1 :(得分:0)
CopyManager cm = new CopyManager(cpds.getConnection().unwrap(PgConnection.class))
对我有用。