MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_112]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:) ~[?:1.8.0_112]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:) ~[?:1.8.0_112]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:) ~[?:1.8.0_112]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.Util.getInstance(Util.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at sun.reflect.GeneratedConstructorAccessor9.newInstance(Unknown Source) ~[?:?]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:) ~[?:1.8.0_112]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:) ~[?:1.8.0_112]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:) ~[mysql-connector-java-5.1..jar:5.1.]
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:) ~[druid-1.1..jar:1.1.]
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:) ~[druid-1.1..jar:1.1.]
    at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:) [druid-1.1..jar:1.1.]

　　这个我在网上查了一些相关的资料,上面有的说是MySQL上面的max_connections没有开启,

show variables like 'max_connections';

set global max_connections=

　　使用上面的可以进行临时开启,想要一直开启就需要去MySQL下面的my.ini文件里修改

　　修改完之后运行发现还是不行,我使用的是DbUtils工具类,在里面传递连接的时候我使用的是connection,没有使用数据源只执行了400多条语句就挂了

　　后来使用datasource就没有出现问题,之后在网上查了一些资料,上面说的是使用数据源dbutils会默认进行资源回收,但是使用connection则不会,需要你在自行回收