我们在应用程序中无法关闭与数据库的连接时遇到麻烦。我什么都试过了，所以我开始试验 DBCP。
以下是重现问题的步骤:
1) 我已经在 Windows 上安装了:
- 清理 apache-tomcat-7.0.59
- Java 1.7.0_75
2) 我更改了 server.xml，添加了一个指向我们数据库的资源
<Resource auth="Container"
defaultTransactionIsolation="READ_COMMITTED"
driverClassName="oracle.jdbc.OracleDriver"
maxActive="20"
initialSize="2"
maxIdle="10"
minIdle="2"
maxWait="10000"
timeBetweenEvictionRunsMillis="60000"
minEvictableIdleTimeMillis="60000"
testOnBorrow="true"
validationInterval="30000"
removeAbandoned="true"
removeAbandonedTimeout="60"
logAbandoned="true"
name="docpilotDB"
password="xxx"
type="javax.sql.DataSource"
url="jdbc:oracle:thin:@1.1.1.1:1521:xe"
username="zzz"
validationQuery="SELECT 1 FROM DUAL"/>
3) 我已将 ojdbc6_g.jar 添加到 tomcat/lib 目录
4) 然后，我使用
创建并部署了应用程序<Context path="/drm">
<ResourceLink global="docpilotDB" name="jdbc/docpilotDB" type="javax.sql.DataSource"/>
</Context>
和一对一测试servlet
<servlet>
<servlet-name>Initial Service</servlet-name>
<servlet-class>net.docucom.csas.oms.drm_x.srvlt.InitialService</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
Servlet类是
public class InitialService extends GenericServlet {
private static final Logger log = LoggerFactory.getLogger(InitialService.class);
private DataSource ds;
public void init(ServletConfig config) throws ServletException {
super.init(config);
try {
ds = getDataSource();
run();
} catch (Exception e) {
throw new ServletException(e);
}
}
private DataSource getDataSource() throws SQLException {
try {
InitialContext ic = new InitialContext();
DataSource ds = (DataSource) ic.lookup("java:comp/env/jdbc/docpilotDB");
return ds;
} catch (NamingException e) {
throw new RuntimeException("Unable to get DataSource", e);
}
}
public void service(ServletRequest arg0, ServletResponse arg1) throws ServletException, IOException {
}
private synchronized void run() throws Exception {
log.info("InitialService: start");
for (int i = 0; i < 100; i++) {
log.info("InitialService: counter=" + i);
Thread.sleep(100);
doSelect();
}
log.info("InitialService: end");
}
synchronized public Connection connect() throws Exception {
int result = -1;
log.debug("connect(): start");
Connection con = null;
try {
con = ds.getConnection();
log.debug("connect(): got connection " + con.getClass().getName());
log.debug("connect(): " + DriverManager.getDriver(ds.getConnection().getMetaData().getURL()).getClass());
result = 0;
} catch (Throwable e) {
log.error("connect() Error!", e);
con = null;
return con;
}
log.debug("connect(): result=" + result);
return con;
}
synchronized public int close(Connection con) throws Exception {
int result = -1;
log.debug("close(): start");
if (con != null) {
log.debug("con.close();");
con.close();
log.debug("con.isClosed=" + con.isClosed());
con = null;
}
result = 0;
log.debug("close(): result=" + result);
return result;
}
public synchronized void doSelect() throws Exception {
log.debug("doSelect(): start");
Connection con = null;
//ResultSet res = null;
try{
con = connect();
// if (stmt == null) {
// stmt = con.createStatement();
// }
//
// res = this.stmt.executeQuery("SELECT * FROM [DRM_OMS].[dbo].[Vat]");
// while (res.next()) {
// String Id = res.getString("id");
// String DPH = res.getString("DPH");
//
// }
//
// res.close();
// res = null;
} finally {
if (con != null){
close(con);
}
}
log.debug("doSelect(): end");
}
}
tomcat服务器上没有其他定制。
在第 20 次迭代之前，日志看起来很漂亮
11:12:58.850 INFO InitialService: start
11:12:58.856 INFO InitialService: counter=0
11:12:58.957 DEBUG doSelect(): start
11:12:58.957 DEBUG connect(): start
11:12:59.056 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:12:59.079 DEBUG connect(): class oracle.jdbc.OracleDriver
11:12:59.079 DEBUG connect(): result=0
11:12:59.079 DEBUG close(): start
11:12:59.079 DEBUG con.close();
11:12:59.079 DEBUG con.isClosed=true
11:12:59.079 DEBUG close(): result=0
11:12:59.080 DEBUG doSelect(): end
11:12:59.080 INFO InitialService: counter=1
11:12:59.180 DEBUG doSelect(): start
11:12:59.180 DEBUG connect(): start
11:12:59.205 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:12:59.761 DEBUG connect(): class oracle.jdbc.OracleDriver
11:12:59.761 DEBUG connect(): result=0
11:12:59.762 DEBUG close(): start
11:12:59.762 DEBUG con.close();
11:12:59.762 DEBUG con.isClosed=true
11:12:59.762 DEBUG close(): result=0
11:12:59.762 DEBUG doSelect(): end
11:12:59.762 INFO InitialService: counter=2
11:12:59.863 DEBUG doSelect(): start
11:12:59.863 DEBUG connect(): start
11:12:59.884 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:00.524 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:00.524 DEBUG connect(): result=0
11:13:00.524 DEBUG close(): start
11:13:00.524 DEBUG con.close();
11:13:00.524 DEBUG con.isClosed=true
11:13:00.524 DEBUG close(): result=0
11:13:00.524 DEBUG doSelect(): end
11:13:00.524 INFO InitialService: counter=3
11:13:00.624 DEBUG doSelect(): start
11:13:00.624 DEBUG connect(): start
11:13:00.679 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:01.315 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:01.315 DEBUG connect(): result=0
11:13:01.315 DEBUG close(): start
11:13:01.316 DEBUG con.close();
11:13:01.316 DEBUG con.isClosed=true
11:13:01.316 DEBUG close(): result=0
11:13:01.316 DEBUG doSelect(): end
11:13:01.316 INFO InitialService: counter=4
11:13:01.416 DEBUG doSelect(): start
11:13:01.416 DEBUG connect(): start
11:13:01.462 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:02.146 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:02.146 DEBUG connect(): result=0
11:13:02.146 DEBUG close(): start
11:13:02.146 DEBUG con.close();
11:13:02.146 DEBUG con.isClosed=true
11:13:02.146 DEBUG close(): result=0
11:13:02.146 DEBUG doSelect(): end
11:13:02.147 INFO InitialService: counter=5
11:13:02.247 DEBUG doSelect(): start
11:13:02.247 DEBUG connect(): start
11:13:02.289 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:02.984 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:02.984 DEBUG connect(): result=0
11:13:02.984 DEBUG close(): start
11:13:02.984 DEBUG con.close();
11:13:02.984 DEBUG con.isClosed=true
11:13:02.984 DEBUG close(): result=0
11:13:02.984 DEBUG doSelect(): end
11:13:02.984 INFO InitialService: counter=6
11:13:03.084 DEBUG doSelect(): start
11:13:03.084 DEBUG connect(): start
11:13:03.118 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:03.447 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:03.447 DEBUG connect(): result=0
11:13:03.447 DEBUG close(): start
11:13:03.447 DEBUG con.close();
11:13:03.447 DEBUG con.isClosed=true
11:13:03.447 DEBUG close(): result=0
11:13:03.447 DEBUG doSelect(): end
11:13:03.447 INFO InitialService: counter=7
11:13:03.547 DEBUG doSelect(): start
11:13:03.547 DEBUG connect(): start
11:13:03.566 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:03.804 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:03.804 DEBUG connect(): result=0
11:13:03.804 DEBUG close(): start
11:13:03.804 DEBUG con.close();
11:13:03.804 DEBUG con.isClosed=true
11:13:03.804 DEBUG close(): result=0
11:13:03.805 DEBUG doSelect(): end
11:13:03.805 INFO InitialService: counter=8
11:13:03.906 DEBUG doSelect(): start
11:13:03.906 DEBUG connect(): start
11:13:03.927 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:04.163 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:04.164 DEBUG connect(): result=0
11:13:04.164 DEBUG close(): start
11:13:04.164 DEBUG con.close();
11:13:04.164 DEBUG con.isClosed=true
11:13:04.164 DEBUG close(): result=0
11:13:04.164 DEBUG doSelect(): end
11:13:04.164 INFO InitialService: counter=9
11:13:04.265 DEBUG doSelect(): start
11:13:04.265 DEBUG connect(): start
11:13:04.282 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:04.517 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:04.518 DEBUG connect(): result=0
11:13:04.518 DEBUG close(): start
11:13:04.518 DEBUG con.close();
11:13:04.518 DEBUG con.isClosed=true
11:13:04.518 DEBUG close(): result=0
11:13:04.518 DEBUG doSelect(): end
11:13:04.518 INFO InitialService: counter=10
11:13:04.618 DEBUG doSelect(): start
11:13:04.618 DEBUG connect(): start
11:13:04.643 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:04.876 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:04.876 DEBUG connect(): result=0
11:13:04.876 DEBUG close(): start
11:13:04.876 DEBUG con.close();
11:13:04.876 DEBUG con.isClosed=true
11:13:04.876 DEBUG close(): result=0
11:13:04.876 DEBUG doSelect(): end
11:13:04.876 INFO InitialService: counter=11
11:13:04.977 DEBUG doSelect(): start
11:13:04.977 DEBUG connect(): start
11:13:04.993 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:05.246 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:05.246 DEBUG connect(): result=0
11:13:05.247 DEBUG close(): start
11:13:05.247 DEBUG con.close();
11:13:05.247 DEBUG con.isClosed=true
11:13:05.247 DEBUG close(): result=0
11:13:05.247 DEBUG doSelect(): end
11:13:05.247 INFO InitialService: counter=12
11:13:05.348 DEBUG doSelect(): start
11:13:05.348 DEBUG connect(): start
11:13:05.371 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:05.639 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:05.639 DEBUG connect(): result=0
11:13:05.640 DEBUG close(): start
11:13:05.640 DEBUG con.close();
11:13:05.640 DEBUG con.isClosed=true
11:13:05.640 DEBUG close(): result=0
11:13:05.640 DEBUG doSelect(): end
11:13:05.640 INFO InitialService: counter=13
11:13:05.740 DEBUG doSelect(): start
11:13:05.740 DEBUG connect(): start
11:13:05.760 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:06.002 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:06.003 DEBUG connect(): result=0
11:13:06.003 DEBUG close(): start
11:13:06.003 DEBUG con.close();
11:13:06.003 DEBUG con.isClosed=true
11:13:06.003 DEBUG close(): result=0
11:13:06.003 DEBUG doSelect(): end
11:13:06.003 INFO InitialService: counter=14
11:13:06.105 DEBUG doSelect(): start
11:13:06.105 DEBUG connect(): start
11:13:06.121 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:06.348 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:06.348 DEBUG connect(): result=0
11:13:06.348 DEBUG close(): start
11:13:06.348 DEBUG con.close();
11:13:06.348 DEBUG con.isClosed=true
11:13:06.348 DEBUG close(): result=0
11:13:06.348 DEBUG doSelect(): end
11:13:06.348 INFO InitialService: counter=15
11:13:06.448 DEBUG doSelect(): start
11:13:06.448 DEBUG connect(): start
11:13:06.467 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:06.747 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:06.747 DEBUG connect(): result=0
11:13:06.747 DEBUG close(): start
11:13:06.747 DEBUG con.close();
11:13:06.747 DEBUG con.isClosed=true
11:13:06.747 DEBUG close(): result=0
11:13:06.747 DEBUG doSelect(): end
11:13:06.747 INFO InitialService: counter=16
11:13:06.848 DEBUG doSelect(): start
11:13:06.848 DEBUG connect(): start
11:13:06.862 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:07.112 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:07.112 DEBUG connect(): result=0
11:13:07.112 DEBUG close(): start
11:13:07.112 DEBUG con.close();
11:13:07.112 DEBUG con.isClosed=true
11:13:07.112 DEBUG close(): result=0
11:13:07.112 DEBUG doSelect(): end
11:13:07.112 INFO InitialService: counter=17
11:13:07.214 DEBUG doSelect(): start
11:13:07.214 DEBUG connect(): start
11:13:07.233 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:07.477 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:07.479 DEBUG connect(): result=0
11:13:07.479 DEBUG close(): start
11:13:07.479 DEBUG con.close();
11:13:07.479 DEBUG con.isClosed=true
11:13:07.479 DEBUG close(): result=0
11:13:07.480 DEBUG doSelect(): end
11:13:07.480 INFO InitialService: counter=18
11:13:07.580 DEBUG doSelect(): start
11:13:07.580 DEBUG connect(): start
11:13:07.603 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:07.866 DEBUG connect(): class oracle.jdbc.OracleDriver
11:13:07.867 DEBUG connect(): result=0
11:13:07.867 DEBUG close(): start
11:13:07.867 DEBUG con.close();
11:13:07.867 DEBUG con.isClosed=true
11:13:07.867 DEBUG close(): result=0
11:13:07.867 DEBUG doSelect(): end
11:13:07.867 INFO InitialService: counter=19
11:13:07.968 DEBUG doSelect(): start
11:13:07.968 DEBUG connect(): start
11:13:07.991 DEBUG connect(): got connection org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
11:13:18.001 ERROR connect() Error!
java.util.NoSuchElementException: Timeout waiting for idle object
at org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1171) ~[tomcat-dbcp.jar:7.0.59]
at org.apache.tomcat.dbcp.dbcp.AbandonedObjectPool.borrowObject(AbandonedObjectPool.java:79) ~[tomcat-dbcp.jar:7.0.59]
at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106) ~[tomcat-dbcp.jar:7.0.59]
... 21 common frames omitted
Wrapped by: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:114) ~[tomcat-dbcp.jar:7.0.59]
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044) ~[tomcat-dbcp.jar:7.0.59]
at net.docucom.csas.oms.drm_x.srvlt.InitialService.connect(InitialService.java:68) [InitialService.class:na]
at net.docucom.csas.oms.drm_x.srvlt.InitialService.doSelect(InitialService.java:99) [InitialService.class:na]
at net.docucom.csas.oms.drm_x.srvlt.InitialService.run(InitialService.java:54) [InitialService.class:na]
at net.docucom.csas.oms.drm_x.srvlt.InitialService.init(InitialService.java:30) [InitialService.class:na]
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284) [catalina.jar:7.0.59]
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197) [catalina.jar:7.0.59]
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) [catalina.jar:7.0.59]
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5262) [catalina.jar:7.0.59]
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5550) [catalina.jar:7.0.59]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [catalina.jar:7.0.59]
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) [catalina.jar:7.0.59]
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) [catalina.jar:7.0.59]
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649) [catalina.jar:7.0.59]
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1081) [catalina.jar:7.0.59]
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1877) [catalina.jar:7.0.59]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [na:1.7.0_75]
at java.util.concurrent.FutureTask.run(FutureTask.java:262) [na:1.7.0_75]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_75]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_75]
at java.lang.Thread.run(Thread.java:745) [na:1.7.0_75]
11:13:18.001 DEBUG doSelect(): end
11:13:18.001 INFO InitialService: counter=20
11:13:18.102 DEBUG doSelect(): start
11:13:18.102 DEBUG connect(): start
在放弃超时后，tomcat 的控制台充满了 DBCP 未关闭的消息。
org.apache.tomcat.dbcp.dbcp.AbandonedTrace$AbandonedObjectException: DBCP object created 2016-02-05 11:12:59 by the following code was never closed:
at org.apache.tomcat.dbcp.dbcp.AbandonedTrace.setStackTrace(AbandonedTrace.java:139)
at org.apache.tomcat.dbcp.dbcp.AbandonedObjectPool.borrowObject(AbandonedObjectPool.java:81)
at org.apache.tomcat.dbcp.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at net.docucom.csas.oms.drm_x.srvlt.InitialService.connect(InitialService.java:68)
at net.docucom.csas.oms.drm_x.srvlt.InitialService.doSelect(InitialService.java:99)
at net.docucom.csas.oms.drm_x.srvlt.InitialService.run(InitialService.java:54)
at net.docucom.csas.oms.drm_x.srvlt.InitialService.init(InitialService.java:30)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5262)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5550)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1081)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1877)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
org.apache.tomcat.dbcp.dbcp.AbandonedTrace$AbandonedObjectException: DBCP object created 2016-02-05 11:12:59 by the following code was never closed:
at org.apache.tomcat.dbcp.dbcp.AbandonedTrace.init(AbandonedTrace.java:90)
at org.apache.tomcat.dbcp.dbcp.AbandonedTrace.<init>(AbandonedTrace.java:73)
at org.apache.tomcat.dbcp.dbcp.DelegatingDatabaseMetaData.<init>(DelegatingDatabaseMetaData.java:52)
at org.apache.tomcat.dbcp.dbcp.DelegatingConnection.getMetaData(DelegatingConnection.java:345)
...................
有人可以帮助解决这个问题吗？现在没有逻辑，我只是在与 DBCP 和通过 DataSource 的连接作斗争。我很确定，我正在关闭连接。 Java代码里写的很清楚。
为什么连接没有关闭？ 请帮忙!
谨致问候，感谢您的宝贵时间和帮助。
马丁·M。
最佳答案
每次通过循环，日志记录都会获得一个额外的连接:
log.debug("connect(): " + DriverManager.getDriver(ds.getConnection().getMetaData().getURL()).getClass());
每次运行时，它都会从数据源获取连接。经过 20 次迭代后，连接池中有 20 个连接“正在使用”。由于 maxActive=20 DataSource 无法创建另一个连接。因此，下一个调用在等待 20 个未使用/未关闭的连接之一关闭时失败。
后来的异常是提示那些从未关闭的连接。
日志行应该使用已经检索到的连接。
log.debug("connect(): " + DriverManager.getDriver(con.getMetaData().getURL()).getClass());
关于java - 由以下代码创建的 DBCP 对象从未关闭，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35221828/