【JDBC】使用c3p0数据库连接池的各种报错警告

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最新推荐文章于 2025-03-17 21:59:45 发布

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使用c3p0数据库连接池的各种报错警告

使用c3p0数据库连接池的时候，先导入了三个jar包在lib 文件夹中，

c3p0-0.9.5.2.jar
mchange-commons-java-0.2.3.4.jar
mysql-connector-java-8.0.13.jar

注意下载的 c3p0 jar包要与mchange-commons-java jar包和mysql-connector-java jar包以及你的mysql版本一致，不一致会报错

然后写c3p0-config.xml配置文件

<c3p0-config>
    <!-- 使用默认的配置读取连接池对象 ，也就是不传参的情况下获取DataSource,使用默认的配置-->
    <default-config>
        <!--  连接参数 -->
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/db3?useSSL=false</property>
        <property name="user">root</property>
        <property name="password">root</property>

        

<!-- 连接池参数 -->
        <!--初始化申请的连接数量-->
        <property name="initialPoolSize">5</property>
        <!--最大的连接数量-->
        <property name="maxPoolSize">10</property>
        <!--超时时间-->
        <property name="checkoutTimeout">3000</property>
    </default-config>

    <named-config name="otherc3p0">
        <!--  连接参数，传参使用这个 -->
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/db3?useSSL=false</property>
        <property name="user">root</property>
        <property name="password">root</property>

        <!-- 连接池参数 -->
        <property name="initialPoolSize">5</property>
        <property name="maxPoolSize">8</property>
        <property name="checkoutTimeout">1000</property>
    </named-config>
</c3p0-config>

在此处要注意版本的不同的差异，如果时mysql 5.x 则在配置文件中
写 <property name="jdbcUrl">jdbc:mysql://localhost:3306/database?useSSL=false</property>
如果是mysql 8之后，<property name="jdbcUrl">jdbc:mysql://localhost:3306/database?useSSL=false&serverTimezone=UTC</property>

如果你这里配置的不对会报错如下

警告: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@2200d7 -- 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: 
java.sql.SQLException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835)
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455)
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
Caused by: com.mysql.cj.exceptions.InvalidConnectionAttributeException: The server time zone value '???ú±ê×??±??' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
	at sun.reflect.GeneratedConstructorAccessor5.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
	at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:85)
	at com.mysql.cj.util.TimeUtil.getCanonicalTimezone(TimeUtil.java:132)
	at com.mysql.cj.protocol.a.NativeProtocol.configureTimezone(NativeProtocol.java:2234)
	at com.mysql.cj.protocol.a.NativeProtocol.initServerSession(NativeProtocol.java:2258)
	at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1319)
	at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:966)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:825)
	... 12 more

然后运行发现报错信息

一月 28, 2021 7:23:24 下午 com.mchange.v2.c3p0.C3P0Registry 
信息: Initializing c3p0-0.9.5.2 [built 08-December-2015 22:06:04 -0800; debug? true; trace: 10]
一月 28, 2021 7:23:24 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource 
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> 1hgeb5tafk6ijyw11flv6q|5387f9e0, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> null, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> 1hgeb5tafk6ijyw11flv6q|5387f9e0, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> null, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
一月 28, 2021 7:23:54 下午 com.mchange.v2.resourcepool.BasicResourcePool 
警告: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@6a2fe339 -- 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: 
java.lang.NullPointerException
	at com.mysql.fabric.jdbc.FabricMySQLDriver.parseFabricURL(FabricMySQLDriver.java:97)
	at com.mysql.fabric.jdbc.FabricMySQLDriver.acceptsURL(FabricMySQLDriver.java:93)
	at java.sql.DriverManager.getDriver(DriverManager.java:299)
	at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:285)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:161)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:161)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:147)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:202)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)

注意其中的关键报错信息点

警告: com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@6a2fe339 -- 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: java.lang.NullPointerException
一般此处报错空指针异常就是我们配置文件位置错误了，xml文件必须放在src文件夹根目录下，前面不能包裹住各种文件夹或包。因为主程序找配置文件是在src根目录下面去找.
（事实上我的文件就在src目录下，但还是报错了这个信息，于是我复制了c3p0-config.xml配置文件将其放在了项目下，也就是说src文件上一级文件的目录下，然后没有报错信息了，我估计是我的project strcture中设置路径有问题，如果你也遇到了和我一样的问题可以这样试一下)

在这里插入图片描述

写一个测试代码看看

package src.cn.itcast.datasource.c3p0;
import com.mchange.v2.c3p0.ComboPooledDataSource;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
/**
 * c3p0的演示
 */
public class C3P0Demo1 {
    public static void main(String[] args) throws SQLException {
        //1.创建数据库连接池对象
        DataSource ds=new ComboPooledDataSource();
        //2.获取连接对象
        Connection conn = ds.getConnection();
        //3.打印
        System.out.println(conn);
    }
}