mybatis学习中遇见的bug

问题1：

报错·：org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): org.example.dao.StudentDao.selectStudentById

 原因:在mapper文件中写接口方法时前面多加了一个空格。。

问题2：

报错：org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating interface org.example.dao.StudentDao with invalid types () or values (). Cause: java.lang.NoSuchMethodException: org.example.dao.StudentDao.()
### The error may exist in org/example/dao/StudentDao.xml
### The error may involve org.example.dao.StudentDao.selectMultiParam
### The error occurred while handling results
### SQL: select id, name,email,age from student where name=? or age=?
### Cause: org.apache.ibatis.reflection.ReflectionException: Error instantiating interface org.example.dao.StudentDao with invalid types () or values (). Cause: java.lang.NoSuchMethodException: org.example.dao.StudentDao.()

 原因：

 在mapper文件中resultTypt导错文件了，应该导Student类。

问题3：在执行insert操作后IDEA中执行成功了，数据库中无结果

原因：少了提交事务这行代码。。。。需执行commit()方法

接口方法：

 int insertstu(Student student);

在映射文件中写sql语句：

 
        insert into student (id, name,email,age)
        values (#{id},#{name},#{email},#{age})
    

 在测试类中写测试方法：

 @Test
    public void testinsert(){
        SqlSession sqlSession=mybatisutils.getSqlSession();
        StudentDao dao=sqlSession.getMapper(StudentDao.class);
        Student student=new Student();
        student.setId(1007);
        student.setAge(90);
        student.setName("姜胜");
        student.setEmail("js.@qq.com");
        int kk=dao.insertstu(student);


        sqlSession.commit();
        sqlSession.close();
        System.out.println(kk);
    }