当我扩展AbstractComboPooledDataSource时，为什么在尝试连接时会收到CannotAcquireResourceException？ [英] Why do I get a CannotAcquireResourceException while trying to connect, when I extend AbstractComboPooledDataSource?
问题描述
在使用Oracle 11数据库的Tomcat 8.5.15环境中，我想实现一个数据源，该数据源处理 context.xml 中的加密密码。例如，而不是：
In a Tomcat 8.5.15 environment using an Oracle 11 database, I want to implement a data source that handles encrypted passwords in the context.xml. For example, instead of having:
<Resource
auth="Container"
description="MyDataSource"
driverClass="oracle.jdbc.OracleDriver"
maxPoolSize="100"
minPoolSize="10"
acquireIncrement="1"
name="jdbc/MyDataSource"
user="me"
password="mypassword"
factory="org.apache.naming.factory.BeanFactory"
type="com.mchange.v2.c3p0.ComboPooledDataSource"
jdbcUrl="jdbc:oracle:thin:@mydb:1521:dev12c"
/>
我想要类似以下内容，其中只有密码和类型已更改：
I'd like to have something like the following, where only the password and type have changed:
<Resource
auth="Container"
description="MyDataSource"
driverClass="oracle.jdbc.OracleDriver"
maxPoolSize="100"
minPoolSize="10"
acquireIncrement="1"
name="jdbc/MyDataSource"
user="me"
password="D364FEC1CBC1DAEB91A1D8997D4A2482B"
factory="org.apache.naming.factory.BeanFactory"
type="com.mycompany.EncryptedC3p0WrappingDataSource"
jdbcUrl="jdbc:oracle:thin:@mydb:1521:dev12c"
/>
主要变化是我对 EncryptedC3p0WrappingDataSource 。 C3p0的ComboPooledDataSource是最终版本，因此我无法对其进行扩展。相反，我扩展了它的超类 AbstractComboPooledDataSource ，并实现了一些其他方法。此类包含 ComboPooledDataSource ，即 wrappedDataSource ，用于通过委派进行实际工作。
The main change is my implementation of the EncryptedC3p0WrappingDataSource. C3p0's ComboPooledDataSource is final, so I can't extend it. Instead, I extend it's superclass, AbstractComboPooledDataSource, and implement some additional methods. This class contains a ComboPooledDataSource, which is the wrappedDataSource, and is used for the actual work via delegation.
public class EncryptedC3p0WrappingDataSource
extends AbstractComboPooledDataSource
implements PooledDataSource, Serializable, Referenceable
{
/** The actual C3P0 data source that will be used to connect to the database. */
private ComboPooledDataSource wrappedDataSource = new ComboPooledDataSource();
// TODO Should this be retrieved from a pool? How?
/** The object that does the encryting/decrypting. */
private Encryptor encryptor;
/**Construct the data source, with the necessary Encryptor. */
public EncryptedC3p0WrappingDataSource() {
try {
encryptor = new Encryptor();
} catch (InvalidKeyException | NoSuchAlgorithmException
| NoSuchPaddingException | UnsupportedEncodingException e) {
log.fatal("Error instantiating decryption class.", e);
throw new RuntimeException(e);
}
}
/**
* Set the in-memory password of the wrapped data source to the decrypted password.
* @param encryptedPassword the encrypted password, as read from a file.
*/
public void setPassword(String encryptedPassword) {
try {
String decryptedPassword
= encryptor.decrypt(encryptedPassword, Encryptor.AES_ALGORITHM);
log.info("***************** Successfully decrypted "
+ encryptedPassword + " to " + decryptedPassword);
wrappedDataSource.setPassword(decryptedPassword);
} catch (Exception e) { e.printStackTrace(); }
}
public void setDriverClass(String driverClass) throws PropertyVetoException {
wrappedDataSource.setDriverClass(driverClass);
}
public void setJdbcUrl(String jdbcUrl) {
wrappedDataSource.setJdbcUrl(jdbcUrl);
}
public void setDescription(String description) {
wrappedDataSource.setDescription(description);
}
public void setMaxPoolSize(int maxPoolSize) {
wrappedDataSource.setMaxPoolSize(maxPoolSize);
}
public void setMinPoolSize(int minPoolSize) {
wrappedDataSource.setMinPoolSize(minPoolSize);
}
public void setAcquireIncrement(int acquireIncrement) {
wrappedDataSource.setAcquireIncrement(acquireIncrement);
}
public Connection getConnection() throws SQLException {
return wrappedDataSource.getConnection();
}
public Connection getConnection(String name, String password) throws SQLException {
return wrappedDataSource.getConnection(name, password);
}
}
当我使用第一个配置在Tomcat下运行应用程序时（ ComboPooledDataSource ），它运行良好。当我尝试第二种配置（ EncryptedC3p0WrappingDataSource ）时，出现以下异常：
When I run our application under Tomcat with the first configuration (ComboPooledDataSource), it runs fine. When I try the second configuration (EncryptedC3p0WrappingDataSource), I get the following exception:
2017-07-21 07:57:29,962 FATAL [XXX.DataSourceFactory] Connections could not be acquired from the underlying database!
java.sql.SQLException: Connections could not be acquired from the underlying database!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:118)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:690)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:140)
at com.mycompany.EncryptedC3p0WrappingDataSource.getConnection(EncryptedC3p0WrappingDataSource.java:116)
...
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:1463)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:639)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:549)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutAndMarkConnectionInUse(C3P0PooledConnectionPool.java:756)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:683)
... 69 more
我在调试器中对此进行了广泛的研究。加密和解密部分似乎正在正确执行。我的 EncryptedC3p0WrappingDataSource.getConnection（）方法导致调用 ComboPooledDataSource.getConnection（）方法（继承的 AbstractPoolBackedDataSource.getConnection（）方法，为什么我会收到异常？
I have looked at this extensively in the debugger. The encryption and decryption part appears to be happening correctly. My EncryptedC3p0WrappingDataSource.getConnection() method results in a call to the ComboPooledDataSource.getConnection() method (the inherited AbstractPoolBackedDataSource.getConnection() method, so why am I getting the exception?
UPDATE：
如果我将get setPassword 方法修改为也使用 setOverrideDefaultPassword ：
If I modify my get setPassword method to also use setOverrideDefaultPassword:
public void setPassword(String encryptedPassword) {
try {
String decryptedPassword
= encryptor.decrypt(encryptedPassword, Encryptor.AES_ALGORITHM);
log.info("***************** Successfully decrypted "
+ encryptedPassword + " to " + decryptedPassword);
wrappedDataSource.setPassword(decryptedPassword);
wrappedDataSource.setOverrideDefaultPassword(decryptedPassword);
} catch (Exception e) { e.printStackTrace(); }
}
我得到了一个不同的例外：
I get a different exception:
Caused by: java.sql.SQLException: com.mchange.v2.c3p0.impl.NewProxyConnection@7e30531e
[wrapping: oracle.jdbc.driver.T4CConnection@51dba714]
is not a wrapper for or implementation of oracle.jdbc.OracleConnection
at com.mchange.v2.c3p0.impl.NewProxyConnection.unwrap(NewProxyConnection.java:1744)
at org.jaffa.security.JDBCSecurityPlugin.executeStoredProcedure(JDBCSecurityPlugin.java:117)
... 67 more
更新2：
我发布了一个密切相关，希望更简单的问题此处。
I've posted a closely related, and hopefully simpler, question here.
推荐答案
该错误是由于类加载问题而导致的，该类加载问题是从多个jar（％CATALINA_HOME％\lib\ojd bc7-12.1.0.2.0.jar 和％CATALINA_HOME％\webapps\my-webapp-1.0.0\WEB-INF\lib\ojdbc7- 12.1.0.2.0.jar ）。当我删除％CATALINA_HOME％\webapps\my-webapp-1.0.0\WEB-INF\lib\ojdbc7-12.1.0.2.0.jar ，我的问题就解决了。
The error was a result of a class loading problem, where the Oracle classes were being loaded from multiple jars (%CATALINA_HOME%\lib\ojdbc7-12.1.0.2.0.jar and %CATALINA_HOME%\webapps\my-webapp-1.0.0\WEB-INF\lib\ojdbc7-12.1.0.2.0.jar) by different class loaders. When I deleted %CATALINA_HOME%\webapps\my-webapp-1.0.0\WEB-INF\lib\ojdbc7-12.1.0.2.0.jar, my problem went away.
These sources (1, 2, 3) discuss this in more detail.
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