mybatis日志能正常打印出正确sql执行语句；数据库有内容；却查询不出来

首先是返回值封装为List的时候获取不到值；为单个对象的时候正常

这个是要执行的调试语句；发现执行完毕控制台如下；sql正确；对象和数据库关系映射也正确；

//执行语句
        List<Object> list = sqlSession.selectList("test.getUserByName", "五");
        for (Object user : list) {
            System.out.println("user"+user);
        }
执行完毕出现下面的问题
DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 733957003.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@2bbf4b8b]
DEBUG [main] - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@2bbf4b8b]
DEBUG [main] - ==> Preparing: select * from user where username LIKE '%五%' 
DEBUG [main] - ==> Parameters: 
DEBUG [main] - <== Total: 0
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@2bbf4b8b]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@2bbf4b8b]
DEBUG [main] - Returned connection 733957003 to pool.

 

然后写了个最简单的demo发现仍然出现问题；检查到最后发现是数据源的url编码问题；没有设置为Utf-8；具体原理还没有找到；希望各位可以解读下原理

jdbc:mysql://localhost:3306/demo?characterEncoding=utf-8" 

更改之后就好了；记录一下，这个错误浪费了半天的时间