一、环境；
IDEA+SSM
二、问题，数据库链接不成功；com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
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:408)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1023)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:997)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:983)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:928)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2576)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2309)
at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:834)
at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:46)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
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:408)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:419)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
at
截图如下：
3、排查问题；
写个测试类测试数据库
3.1、确保jdbc.properties数据库连接池无误，包括用户名和密码都正确，数据库名正确；
3.2、确保beans.xml连接池设置无误
3.3、测试类
结果报同样的异常；
检查当前mysql-contector-java版本为；
<mysql.version>5.1.32</mysql.version>
mysql
mysql-connector-java
${mysql.version}
尝试改成<mysql.version>5.1.46</mysql.version>最新的版本；
重新load jar，mvn clean install;
问题得到解决；
4、总结：mysql-connector-java的版本尽量选与你的环境相匹配的版本。遇到这个问题时可以尝试修改版本。
