我试图关闭我的数据库连接，只是为了找出调用的异常类型。
我有我的 entity 这是我想保存的。

try {
            dataService.save(dataLogg);
        }catch(TransactionException e1) {

            System.out.println("hello Sending message!");
            mailService.sendMessage(alarm, email, "Database connection is refused. Make sure that database is reestablish, or else, you cannot login. Logging shutting down.", message);
            break; // This will jump out of the while loop
        }catch(JDBCConnectionException e2) {
            System.out.println("hello JDBC!");
        }catch(Exception e3) {
            System.out.println("hello!" + e3.getCause());
            saveDataLater.add(dataLogg); // Save it for later if something just happen
        }

但我的错误是 TransactionException 它被称为： catch(Exception e3) 而不是 catch(TransactionException e1) .
为什么会这样？
错误：

2021-01-05 15:11:50.438  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.ProxyConnection   : HikariPool-1 - Connection com.mysql.cj.jdbc.ConnectionImpl@7a66ace6 marked as broken because of SQLSTATE(08S01), ErrorCode(0)

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet successfully received from the server was 4 milliseconds ago. The last packet sent successfully to the server was 4 milliseconds ago.
    at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:2056) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.zaxxer.hikari.pool.ProxyConnection.setAutoCommit(ProxyConnection.java:393) ~[HikariCP-3.4.1.jar:na]
    at com.zaxxer.hikari.pool.HikariProxyConnection.setAutoCommit(HikariProxyConnection.java) ~[HikariCP-3.4.1.jar:na]
    at org.hibernate.resource.jdbc.internal.AbstractLogicalConnectionImplementor.begin(AbstractLogicalConnectionImplementor.java:67) ~[hibernate-core-5.4.6.Final.jar:5.4.6.Final]
    at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:259) ~[hibernate-core-5.4.6.Final.jar:5.4.6.Final]
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:246) ~[hibernate-core-5.4.6.Final.jar:5.4.6.Final]
    at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:83) ~[hibernate-core-5.4.6.Final.jar:5.4.6.Final]
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:184) ~[spring-orm-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:402) ~[spring-orm-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:376) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:560) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:347) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178) ~[spring-data-jpa-2.2.0.RELEASE.jar:2.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.0.RELEASE.jar:5.2.0.RELEASE]
    at com.sun.proxy.$Proxy133.save(Unknown Source) ~[na:na]
    at se.danielmartensson.service.DataService.save(DataService.java:26) ~[classes/:na]
    at se.danielmartensson.threads.SamplingThread.run(SamplingThread.java:217) ~[classes/:na]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet successfully received from the server was 4 milliseconds ago. The last packet sent successfully to the server was 4 milliseconds ago.
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:na]
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490) ~[na:na]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:539) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.checkErrorMessage(NativeProtocol.java:703) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.sendCommand(NativeProtocol.java:642) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.sendQueryPacket(NativeProtocol.java:941) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.sendQueryString(NativeProtocol.java:887) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.NativeSession.execSQL(NativeSession.java:1073) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:2046) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    ... 23 common frames omitted
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
    at com.mysql.cj.protocol.FullReadInputStream.readFully(FullReadInputStream.java:67) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:63) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:45) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.TimeTrackingPacketReader.readHeader(TimeTrackingPacketReader.java:52) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.TimeTrackingPacketReader.readHeader(TimeTrackingPacketReader.java:41) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.MultiPacketReader.readHeader(MultiPacketReader.java:54) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.MultiPacketReader.readHeader(MultiPacketReader.java:44) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:533) ~[mysql-connector-java-8.0.18.jar:8.0.18]
    ... 29 common frames omitted

hello!org.hibernate.TransactionException: JDBC begin transaction failed: 
2021-01-05 15:11:52.121  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@70ff6675 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.123  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@342f2edc (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.125  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@52b7731f (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.126  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@22613161 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.130  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@29262796 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.132  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@64b2b5a0 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.134  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@d740da2 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.137  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@4f59fb40 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:11:52.140  WARN 9685 --- [      Thread-15] com.zaxxer.hikari.pool.PoolBase          : HikariPool-1 - Failed to validate connection com.mysql.cj.jdbc.ConnectionImpl@62ede614 (No operations allowed after connection closed.). Possibly consider using a shorter maxLifetime value.
2021-01-05 15:12:22.122  WARN 9685 --- [      Thread-15] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 0, SQLState: null
2021-01-05 15:12:22.122 ERROR 9685 --- [      Thread-15] o.h.engine.jdbc.spi.SqlExceptionHelper   : HikariPool-1 - Connection is not available, request timed out after 30001ms.
hello!org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection