老师每次使用C3P0自动连接配置文件总会报错

使用自动加载报错，，不使用自动加载，手动输入地址就不会报错

文件名：c3p0.properties

driverClass=com.mysql.jdbc.Driver
jdbcUrl=jdbc:mysql:///imoocuseSSL=false&serverTimezone=Hongkong&useUnicode=true&characterEncoding=utf-8
username=root
password=root

二月 05, 2020 5:14:12 下午 com.mchange.v2.log.MLog <clinit>
信息: MLog clients using java 1.4+ standard logging.
二月 05, 2020 5:14:12 下午 com.mchange.v2.c3p0.C3P0Registry banner
信息: Initializing c3p0-0.9.1.2 [built 21-May-2007 15:04:56; debug? true; trace: 10]
二月 05, 2020 5:14:12 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
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, dataSourceName -> 1hge1hea85q1uxz1aknzhu|7dc222ae, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> null, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge1hea85q1uxz1aknzhu|7dc222ae, idleConnectionTestPeriod -> 0, initialPoolSize -> 3, jdbcUrl -> null, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, numThreadsAwaitingCheckoutDefaultUser -> 0, preferredTestQuery -> null, properties -> {}, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false ]
二月 05, 2020 5:14:41 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run
警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5d4c6456 -- 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: No suitable driver
 at java.sql.DriverManager.getDriver(Unknown Source)
 at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
 at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
 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)

二月 05, 2020 5:14:41 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run
警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@73ee8e7d -- 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: No suitable driver
 at java.sql.DriverManager.getDriver(Unknown Source)
 at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
 at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
 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)

二月 05, 2020 5:14:41 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run
警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@12e7e342 -- 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: No suitable driver
 at java.sql.DriverManager.getDriver(Unknown Source)
 at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
 at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
 at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
 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)

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 com.imooc.jdbcdemo1.JdbcUtils1.getConnection(JdbcUtils1.java:44)
 at com.imooc.jdbcdemo1.JdbcDemo1.jdbcDemo2(JdbcDemo1.java:21)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
 at java.lang.reflect.Method.invoke(Unknown Source)
 at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
 at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
 at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
 at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
 at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
 at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
 at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
 at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
 at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
 at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
 at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
 at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
 at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
 at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
 at org.junit.vintage.engine.execution.RunnerExecutor.execute(RunnerExecutor.java:40)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
 at java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
 at java.util.Iterator.forEachRemaining(Unknown Source)
 at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Unknown Source)
 at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
 at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
 at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
 at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
 at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
 at java.util.stream.ReferencePipeline.forEach(Unknown Source)
 at org.junit.vintage.engine.VintageTestEngine.executeAllChildren(VintageTestEngine.java:80)
 at org.junit.vintage.engine.VintageTestEngine.execute(VintageTestEngine.java:71)
 at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:229)
 at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:197)
 at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:211)
 at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:191)
 at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:137)
 at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:89)
 at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
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)
 ... 46 more

添加下面不报错：

private static final String driverClass;
 private static final String jdbcUrl;
 private static final String username;
 private static final String password;
 
 static {
  Properties p=new Properties();
  InputStream inStream=JdbcUtils1.class.getClassLoader().getResourceAsStream("c3p0.properties");
  try {
   p.load(inStream);
  } catch (IOException e) {
   e.printStackTrace();
  }
  
  driverClass=p.getProperty("driverClass");
  jdbcUrl=p.getProperty("jdbcUrl");
  username=p.getProperty("username");
  password=p.getProperty("password");
 }

完。