錯誤信息如下：
2019-12-01 15:36:11.018 WARN 30232 --- [ main] c.a.d.p.v.MySqlValidConnectionChecker : Cannot resolve com.mysq.jdbc.Connection.ping method. Will use 'SELECT 1' instead.
java.lang.NullPointerException: null
at com.alibaba.druid.pool.vendor.MySqlValidConnectionChecker.<init>(MySqlValidConnectionChecker.java:48) ~[druid-1.0.12.jar:1.0.12]
at com.alibaba.druid.pool.DruidDataSource.initValidConnectionChecker(DruidDataSource.java:892) [druid-1.0.12.jar:1.0.12]
at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:608) [druid-1.0.12.jar:1.0.12]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:934) [druid-1.0.12.jar:1.0.12]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:930) [druid-1.0.12.jar:1.0.12]
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:102) [druid-1.0.12.jar:1.0.12]
at com.waectr.springbootmybatis.SpringbootMybatisApplicationTests.contextLoads(SpringbootMybatisApplicationTests.java:20) [test-classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:675) [junit-platform-commons-1.5.2.jar:1.5.2]
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60) [junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:125) [junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:132) [junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:124) [junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:74) [junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:104) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:62) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:43) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:35) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:202) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:198) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:69) ~[junit-jupiter-engine-5.5.2.jar:5.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:135) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at java.util.ArrayList.forEach(ArrayList.java:1257) ~[na:1.8.0_191]
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at java.util.ArrayList.forEach(ArrayList.java:1257) ~[na:1.8.0_191]
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51) ~[junit-platform-engine-1.5.2.jar:1.5.2]
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:229) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:197) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:211) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:191) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128) ~[junit-platform-launcher-1.5.2.jar:1.5.2]
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:74) ~[junit5-rt.jar:na]
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47) ~[junit-rt.jar:na]
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242) ~[junit-rt.jar:na]
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70) ~[junit-rt.jar:na]
2019-12-01 15:36:11.040 INFO 30232 --- [ main] com.alibaba.druid.pool.DruidDataSource : {dataSource-1} inited
2019-12-01 15:36:11.255 ERROR 30232 --- [eate-1842102517] com.alibaba.druid.pool.DruidDataSource : create connection error, url: jdbc:mysql://localhost:3306/demo?characterEncoding=utf8&useSSL=true&serverTimezone=UTC
經過查找：
改配置的yml文件如下：
spring:
datasource:
username: root
password: root
url: jdbc:mysql://localhost:3306/demo?characterEncoding=utf8&useSSL=true&serverTimezone=UTC
driver-class-name: com.mysql.cj.jdbc.Driver
#指定數據源
type: com.alibaba.druid.pool.DruidDataSource
特別注意以下兩個點：
driver-class-name: com.mysql.cj.jdbc.Driver
url後面要加 serverTimezone=UTC