老师你好，启动后报错，说数据库无法连接 不知道是什么情况

Question

2020-06-02 11:40:22.345 [Druid-ConnectionPool-Create-1896085078] ERROR com.alibaba.druid.pool.DruidDataSource - create connection error, url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=UTF-8, errorCode 0, state 08001
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
	at sun.reflect.GeneratedConstructorAccessor13.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.Util.getInstance(Util.java:384)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:973)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2588)
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2321)
	at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
	at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
	at sun.reflect.GeneratedConstructorAccessor10.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
	at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:148)
	at com.alibaba.druid.filter.FilterAdapter.connection_connect(FilterAdapter.java:785)
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
	at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:211)
	at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1410)
	at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1464)
	at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1995)
Caused by: java.lang.NullPointerException: null
	at com.mysql.jdbc.ConnectionImpl.getServerCharacterEncoding(ConnectionImpl.java:3307)
	at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1985)
	at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1911)
	at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1288)
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2506)
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2539)
	... 17 common frames omitted

pom.xml

<!-- mybatis -->
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis</artifactId>
  <version>3.4.0</version>
</dependency>
<dependency>
  <groupId>org.mybatis</groupId>
  <artifactId>mybatis-spring</artifactId>
  <version>1.3.0</version>
</dependency>

<!-- mysql -->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.30</version>
</dependency>

settings.properties

db.driverClassName=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=UTF-8
db.username=root
db.password=root

Answer 1

Jimin 2020-06-02 12:08:27

好的，看着用的还是mysql的高版本

• 提问者 黃金葉 #1

  非常感谢！

Answer 2

提问者 黃金葉 2020-06-02 12:01:18

已解决，是由于MySQL依赖引起的。

解决方法如下：

<!-- mysql -->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>8.0.11</version>
</dependency>

首先将mysql版本依赖更新成8.0.11

其次更新setting.properties

db.driverClassName=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8
db.username=root
db.password=root

发现还是启动失败，原因是druid版本也需要随之更新

<!-- druid -->
<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>druid</artifactId>
  <version>1.1.11</version>
</dependency>

即可启动成功