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:62) ~[?:1.8.0_112]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_112]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_112]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.Util.getInstance(Util.java:408) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1040) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2205) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2236) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2035) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at sun.reflect.GeneratedConstructorAccessor9.newInstance(Unknown Source) ~[?:?]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.8.0_112]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[?:1.8.0_112]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330) ~[mysql-connector-java-5.1.41.jar:5.1.41]
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1558) ~[druid-1.1.10.jar:1.1.10]
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1623) ~[druid-1.1.10.jar:1.1.10]
    at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2468) [druid-1.1.10.jar:1.1.10]

　　這個我在網上查了一些相關的資料,上面有的說是MySQL上面的max_connections沒有開啟,

show variables like 'max_connections';

set global max_connections=1000

　　使用上面的可以進行臨時開啟,想要一直開啟就需要去MySQL下面的my.ini文件里修改

　　修改完之后運行發現還是不行,我使用的是DbUtils工具類,在里面傳遞連接的時候我使用的是connection,沒有使用數據源只執行了400多條語句就掛了

　　后來使用datasource就沒有出現問題,之后在網上查了一些資料,上面說的是使用數據源dbutils會默認進行資源回收,但是使用connection則不會,需要你在自行回收