c3p0无法连接的相关处理,问题：Connections could not be acquired from the underlying database!

最新推荐文章于 2024-12-21 13:56:23 发布

原创最新推荐文章于 2024-12-21 13:56:23 发布 · 410 阅读

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文章标签：

#mysql #数据库 #jdbc #java

本文详细解析了java.sql.SQLException: Connection could not be acquired from the underlying database异常的原因及解决方案，涉及MySQL版本与JDBC驱动匹配、配置错误、权限设置等关键点，提供具体操作步骤与参考资料。

我遇到的问题：

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.

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处理结果

我的是因为mysql的版本和jdbc的jar包对应版本不同，每个版本的mysql有相对应的驱动jar包
特附上相关的对应关系

Table 2.1 Summary of Connector/J Versions

Connector/J version	JDBC version	MySQL Server version	JRE Required	DK Required for Compilation	Status
8.0	4.2 1	5.6, 5.7, 8.0	JRE 8 or higher	JDK 8.0 or higher3	General availability. Recommended version
5.1	3.0, 4.0, 4.1, 4.2	5.62, 5.72, 8.02	JRE 5 or higher2	JDK 5.0 AND JDK 8.0 or higher3	General availability

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其他原因：

1，驱动配置有误：driver=com.mysql.jdbc.Driver
2，数据库连接地址有误：url=jdbc:mysql://localhost:3306/test?3useUnicode=true&characterEncoding=utf8
3，密码或帐号有误：username=root
      password=root

4，数据库未启动或无权访问

5，项目未引入对应的驱动jar包mysql-connector-java-5.1.6-bin.jar

6,mysql root没有远程访问的权限，需要增加权限，增加权限的步骤如下：
进入mysql数据库：
grant all privileges on *.* to 'root'@'%' identified by 'root' with grant option;
flush privileges;

参考文章：

https://www.iteye.com/blog/jyao-1915561
https://blog.youkuaiyun.com/hchhan/article/details/81106992
https://dev.mysql.com/doc/connector-j/8.0/en/connector-j-versions.html