Unknown system variable 'tx_isolation'Connections could not be acquired from the underlying database

矫情吗；* 2021-06-22 15:37 397阅读 0赞

# 前后出现的几个关键错误信息 #

java.sql.SQLException: Unknown system variable ‘tx\_isolation’   
  
java.lang.RuntimeException: java.sql.SQLException: Connections could not be acquired from the underlying database!  
  
Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!  
  
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.

# 背景 #

**maven+spring的演示demo**

MySQL的版本：  
![在这里插入图片描述][20200511163216863.png]  
连接池的datasource的四项配置：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ1NjUxMjc_size_16_color_FFFFFF_t_70]  
jdbc的版本：  
![在这里插入图片描述][20200511163424862.png]

# 问题 #

**运行之后，  
首先出现的是这样的错误：**

五月 11, 2020 4:26:41 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run
    警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1bfed88e -- 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: Unknown system variable 'tx_isolation'
    	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)
    	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:956)
    	...
    	...
    
    
    java.lang.RuntimeException: java.sql.SQLException: Connections could not be acquired from the underlying database!
    
    	at com.veeja.dao.impl.AccountDaoImpl.findAll(AccountDaoImpl.java:29)
    	at com.veeja.service.impl.AccountServiceImpl.findAllAccount(AccountServiceImpl.java:23)
    	...
    	...
    	
    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)
    	...
    	...
    	
    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)
    	... 
    	...

**这个问题，是因为我们的mysql版本太高，而jdbc版本跟不上。  
这个时候我们要么把mysql给降级，要么把jdbc给升级，哈哈哈，那还不是废话吗，当然是改一下jdbc的版本，毕竟是maven项目，动动就完事了。**  
改成：  
![在这里插入图片描述][20200511164347915.png]

然而又出现了这样的错误，关键信息在于**java.sql.SQLException: The server time zone value ‘�й���׼ʱ��’ is unrecognized or represents**

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
    五月 11, 2020 4:39:58 下午 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask run
    警告: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@5dcd76d7 -- 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: The server time zone value '�й���׼ʱ��' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
    	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
    	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    	...
    	...

**我们需要添加一个servertime之类的玩意，稍微做更改：**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ1NjUxMjc_size_16_color_FFFFFF_t_70 1]

试运行：

![在这里插入图片描述][20200511165157332.png]  
成功了。

--------------------

我套他猴子，一波三折，浪费我甚多时间哪~~

[20200511163216863.png]: /images/20210615/d93ce7a3f3bf45129d5d304f376ddc76.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ1NjUxMjc_size_16_color_FFFFFF_t_70]: /images/20210615/22207ec54fb34a36a168065f16eeee73.png
[20200511163424862.png]: /images/20210615/961b5ec6521e45bba4dd5afb8163e3a5.png
[20200511164347915.png]: /images/20210615/b64131d940c34be086d82c32a80bef47.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3UwMTQ1NjUxMjc_size_16_color_FFFFFF_t_70 1]: /images/20210615/b5031fae07764cf9879d4993b7db7762.png
[20200511165157332.png]: /images/20210615/482a353e787b4c3cb0cb8e3b7569576c.png