MySQL运行报错java.sql.SQLException:null,message from server:“Host ‘‘ is not allowed to connect toMySQL

java连接数据库遇到错误如下所示：

aused by: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: null,  message from server: "Host 'mall.ljw.com' is not allowed to connect to this MySQL server"
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:82)
	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80)
	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337)
	at com.baomidou.mybatisplus.core.executor.MybatisSimpleExecutor.prepareStatement(MybatisSimpleExecutor.java:93)
	at com.baomidou.mybatisplus.core.executor.MybatisSimpleExecutor.doQuery(MybatisSimpleExecutor.java:68)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at com.baomidou.mybatisplus.core.executor.MybatisCachingExecutor.query(MybatisCachingExecutor.java:165)
	at com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor.intercept(MybatisPlusInterceptor.java:81)
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61)
	at com.sun.proxy.$Proxy99.query(Unknown Source)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)
	... 69 common frames omitted
Caused by: java.sql.SQLException: null,  message from server: "Host 'mall.ljw.com' is not allowed to connect to this MySQL server"
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836)
	at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456)
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
	at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138)
	at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:358)
	at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206)
	at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:477)
	at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:560)
	at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115)
	at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112)
	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158)
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116)
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79)
	... 81 common frames omitted

简单概括:java.sql.SQLException: null, message from server: "Host 'mall.ljw.com' is not allowed to connect to this MySQL server"

原因分析

连接服务器不允许Java程序访问它的数据库。所以，我们要对远程服务器进行设置，使它允许你进行连接。

解决方案

连接MySQL服务，打开mysql数据库，打开user表

设置 user =‘root’ 的 host =‘%’

目的: 远程服务器进行设置，使它允许你进行连接，设置Host可以被任意主机访问连接

重启MySQL服务

重新访问

正常运行，无报错信息。