添加spring boot devtools 依赖包 报错： 导致 the url can not null

添加spring boot devtools依赖包时导致的the url  can not null

springboot devtools 配置如下。

 
       
            org.springframework.boot
            spring-boot-devtools
            true
            true
        

错误：

2019-09-15 22:13:11.944  WARN 1924 --- [           main] o.a.tomcat.jdbc.pool.PooledConnection    : Not loading a JDBC driver as driverClassName property is null.
2019-09-15 22:13:11.959 ERROR 1924 --- [           main] o.a.tomcat.jdbc.pool.ConnectionPool      : Unable to create initial connections of pool.

java.sql.SQLException: The url cannot be null
	at java.sql.DriverManager.getConnection(DriverManager.java:649) ~[na:1.8.0_202]
	at java.sql.DriverManager.getConnection(DriverManager.java:208) ~[na:1.8.0_202]
	at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:317) ~[tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:212) ~[tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:744) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:676) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:483) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.ConnectionPool.(ConnectionPool.java:154) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107) [tomcat-jdbc-9.0.24.jar:na]
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:131) [tomcat-jdbc-9.0.24.jar:na]
	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78) [spring-jdbc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:81) [mybatis-spring-1.2.2.jar:1.2.2]
	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67) [mybatis-spring-1.2.2.jar:1.2.2]
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:279) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:72) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102) [mybatis-3.2.8.jar:3.2.8]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358) [mybatis-spring-1.2.2.jar:1.2.2]
	at com.sun.proxy.$Proxy57.selectList(Unknown Source) [na:na]
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:198) [mybatis-spring-1.2.2.jar:1.2.2]
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:119) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63) [mybatis-3.2.8.jar:3.2.8]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52) [mybatis-3.2.8.jar:3.2.8]
	at com.sun.proxy.$Proxy76.findUserInfo(Unknown Source) [na:na]
	at com.example.demo.service.UserService.findUsers(UserService.java:20) [classes/:na]
	at com.example.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:25) [test-classes/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) [junit-4.12.jar:4.12]
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) [junit-4.12.jar:4.12]
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) [junit-4.12.jar:4.12]
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) [junit-4.12.jar:4.12]
	at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325) [junit-4.12.jar:4.12]
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) [junit-4.12.jar:4.12]
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) [junit-4.12.jar:4.12]
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) [junit-4.12.jar:4.12]
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) [junit-4.12.jar:4.12]
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) [junit-4.12.jar:4.12]
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363) [junit-4.12.jar:4.12]
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190) [spring-test-5.1.9.RELEASE.jar:5.1.9.RELEASE]
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137) [junit-4.12.jar:4.12]
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) [junit-rt.jar:na]
	at com.intellij.rt.execution.junit.IdeaTestRunner$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]


org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: The url cannot be null
### The error may exist in file [D:\workspace\demo\target\classes\mybatis\UserMapper.xml]
### The error may involve com.example.demo.mapper.UserMapper.findUserInfo
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: The url cannot be null

	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:75)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:371)
	at com.sun.proxy.$Proxy57.selectList(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:198)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:119)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)
	at com.sun.proxy.$Proxy76.findUserInfo(Unknown Source)
	at com.example.demo.service.UserService.findUsers(UserService.java:20)
	at com.example.demo.DemoApplicationTests.contextLoads(DemoApplicationTests.java:25)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	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.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	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$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: The url cannot be null
### The error may exist in file [D:\workspace\demo\target\classes\mybatis\UserMapper.xml]
### The error may involve com.example.demo.mapper.UserMapper.findUserInfo
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: The url cannot be null
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)
	... 38 more
Caused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: The url cannot be null
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:81)
	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:81)
	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:279)
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:72)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:59)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)
	... 44 more
Caused by: java.sql.SQLException: The url cannot be null
	at java.sql.DriverManager.getConnection(DriverManager.java:649)
	at java.sql.DriverManager.getConnection(DriverManager.java:208)
	at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:317)
	at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:212)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:744)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:676)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:483)
	at org.apache.tomcat.jdbc.pool.ConnectionPool.(ConnectionPool.java:154)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107)
	at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:131)
	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157)
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
	... 54 more

解决办法：去掉springboot-devtools这个jar包的依赖