JDBC报错Unsupported major.minor version 52.0

版本问题，jdk version "1.7.0_17"，
之前用的依赖是6.0.6，相对于jdk版本过高：

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>6.0.6</version>
    </dependency>

改依赖版本为5.1.22：

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.22</version>
    </dependency>