无法创建池的初始连接，无法获取JDBC连接错误

Question

我有一个Spring Boot数据JPA应用程序，正在其中创建两个数据源。我的应用程序启动时出现此错误。

1. org.apache.tomcat.jdbc.pool.ConnectionPool init
SEVERE: Unable to create initial connections of pool.
java.sql.SQLException
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:253)
2. Caused by: java.lang.NullPointerException
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:245)
    ... 88 more

3. Jan 20, 2020 7:39:29 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: null
[http-bio-8080-exec-1] ERROR org.springframework.boot.web.support.ErrorPageFilter - Forwarding to error page from request [/orderForDateTopK/1/2] due to exception [Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection]
org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
    at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:431)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)

4. Caused by: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692)

5. Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection

Answer 1

您正在为数据源使用Tomcat JDBC连接池，但是在application.properties中为Hikari数据源配置了连接池。

您的datasource实例化不佳，因为连接池设置。

您的错误配置：

#HikariCP settings
spring.datasource.hikari.connection-timeout=60000
spring.datasource.hikari.maximum-pool-size=15
spring.datasource.hikari.minimum-idle=1

---

您有2个解决方案

1-将连接池设置从hikari更改为tomcat

像这样

spring.datasource.tomcat.initial-size=
spring.datasource.tomcat.max-wait=
spring.datasource.tomcat.max-active=
spring.datasource.tomcat.max-idle=
spring.datasource.tomcat.min-idle=
spring.datasource.tomcat.default-auto-commit=
//..

此领域的一些有用指南：

Configuring a Tomcat Connection Pool

2-使用Hikari连接池代替tomcat（更改数据源连接池）

此领域的一些有用指南：

A Simple Guide to Connection Pooling in Java

Introduction to HikariCP