Spring 结合C3P0 无法连接对象

数据库和mysql的版本
Spring 版本 4.2.4
mysql 版本 8.0.13
其他的版本对应在下方
数据库的账号密码都是对的，在java项目中能正常运行，在Spring中获取不了连接对象。
问题已查明：mysql版本原因。见最后！

spring-expression-4.2.4.RELEASE.jar
spring-beans-4.2.4.RELEASE.jar
spring-context-4.2.4.RELEASE.jar
spring-core-4.2.4.RELEASE.jar
com.springsource.org.apache.commons.logging-1.1.1.jar
com.springsource.org.apache.log4j-1.2.15.jar
com.springsource.org.aopalliance-1.0.0.jar
com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
spring-aop-4.2.4.RELEASE.jar
spring-aspects-4.2.4.RELEASE.jar
mysql-connector-java-8.0.20.jar
spring-jdbc-4.2.4.RELEASE.jar
com.springsource.com.mchange.v2.c3p0-0.9.1.2.jar
spring-tx-4.2.4.RELEASE.jar
spring-test-4.2.4.RELEASE.jar

java

package com.coopll.a_jdbctemplate;

import org.junit.Test;
import org.springframework.jdbc.core.JdbcTemplate;

import com.mchange.v2.c3p0.ComboPooledDataSource;

//演示JDBC
public class Demo01 {
    @Test
    public void fun1() throws Exception{
        //0_准备连接池
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("com.mysql.cj.jdbc.Driver");
        dataSource.setJdbcUrl("jdbc:mysql://localhost/hibernate_32?characterEncoding=utf8&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true");
        dataSource.setUser("root");
        dataSource.setPassword("root");

        //1_创建JDBC模板对象
        JdbcTemplate jt = new JdbcTemplate();
        jt.setDataSource(dataSource);

        //2_书写SQL，并执行
        String sql = "insert into t_user values(null,'rose')";
        jt.update(sql);



    }
}

报错：无法获取对象，而用C3P0的java项目代码运行没问题

org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
    at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:80)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:390)
    at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:534)
    at com.coopll.a_jdbctemplate.Demo01.fun1(Demo01.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.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.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.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: 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 org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111)
    at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)
    ... 26 more
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)
    ... 29 more

补充：

常识将数据库换成自己服务器上的低版本，却成功了。
服务器上的mysql版本5.5.34
两个版本的驱动都成功了
mysql-connector-java-5.1.7-bin.jar
mysql-connector-java-8.0.20.jar

8.0之前的隔离级别变量名是tx_isolation
8.0 之后变成了transaction_isolation
SHOW VARIABLES LIKE 'transaction_isolation';
SHOW VARIABLES LIKE 'tx_isolation';

导致了程序报错：java.sql.SQLException: Unknown system variable ‘tx_isolation’

https://blog.csdn.net/qq_37638061/article/details/81056184