Question

我正在尝试从ComboPooledDataSource 获取连接，但我们说我在密码中输入了错误。我想获得有关实际错误原因的信息，但是我可以从抛出的异常中找到出错的地方。有没有办法找出真正的问题，以字符串的形式显示给用户？

我正在使用 c3po-0.9.1.2 。

让我们具体一点，我的代码如下：

ComboPooledDataSource ds = new ComboPooledDataSource();
ds.setDriverClass("org.postgresql.Driver");
ds.setJdbcUrl("jdbc:postgresql://localhost:5432/my_db");
ds.setUser("user1");
ds.setPassword("wrong-password");

try {
    Connection c = ds.getConnection();
    ...
} catch (Exception e) {
    e.printStackTrace();
}

ds.getConnection()代码抛出异常，打印以下stakctrace：

java.sql.SQLException: Connections could not be acquired from the underlying database!
    at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
    at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
    at test.ConnectionErrorDemo.main(ConnectionErrorDemo.java:21)
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
    at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
    at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
    at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
    ... 2 more

因此，这个例外根本没有用，因为它没有说明问题的实际原因。但是，在控制台中，您还可以看到这样的日志条目，它们描述了实际问题：

WARNING: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@249939c3 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
org.postgresql.util.PSQLException: FATAL: password authentication failed for user "user1"
    at org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:398)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:173)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:64)
    at org.postgresql.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:136)
    at org.postgresql.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:29)
    at org.postgresql.jdbc3g.AbstractJdbc3gConnection.<init>(AbstractJdbc3gConnection.java:21)
    at org.postgresql.jdbc4.AbstractJdbc4Connection.<init>(AbstractJdbc4Connection.java:31)
    at org.postgresql.jdbc4.Jdbc4Connection.<init>(Jdbc4Connection.java:24)
    at org.postgresql.Driver.makeConnection(Driver.java:393)
    at org.postgresql.Driver.connect(Driver.java:267)
    at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
    at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
    at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
    at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

如果我理解正确，这个日志条目是由c3po库本身完成的，因此我想也许有办法以某种方式访问这些信息。有什么想法吗？

获取与c3po ComboPooledDataSource的连接时发现真正的错误原因

0 个答案: