入門三 sqlMapper文件

增加

　　1.增刪改在接口中的返回值

　　　　Integer、Long、Boolean、void 返回影響多少行 或 true | false

　　2.mapper 中 增刪改沒有返回值 (resultType或resultMap)

　　3.mysql支持自增主鍵，自增主鍵的值的獲取，mybatis利用statement.getGeneratedKey();
　　userGeneratedKeys="true" ：使用自增主鍵獲取主鍵的策略
　　keyProperty:指定對應的主鍵屬性，也就是mybatis獲取到主鍵值以后，將這個值封裝到JavaBean中哪個屬性中

　　獲取則是通過插入后，在查詢一遍插入的對象，就可以拿到主鍵值
　　4.sqlSessionFactory.openSession()需要手動提交事務，或者采用sqlSessionFactory.openSession(true)

public interface EmployeeMapper {


    Integer addEmp(Employee employee);

}

    <!--
        mysql支持自增主鍵，自增主鍵的值的獲取，mybatis利用statement.getGeneratedKey();
        userGeneratedKeys="true" ：使用自增主鍵獲取主鍵的策略
        keyProperty:指定對應的主鍵屬性，也就是mybatis獲取到主鍵值以后，將這個值封裝到JavaBean中哪個屬性中
    -->
    <insert id="addEmp" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO tbl_employee(last_name, email, gender)
        VALUES (#{name}, #{email}, #{gender})
    </insert>

    @Test
    public void addEmp() throws IOException {
        //讀取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        //創建sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //獲取sqlSession實例，能直接執行已經映射的sql語句
　　　　　//不會自動提交，除非在openSession(true)
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //執行查詢方法
        try {
            EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
            Employee employee = new Employee(null,"麥克雷",'1',"[e-mail]");
            //i判斷是否插入成功
            Integer i = mapper.addEmp(employee);
            System.out.println(i);
            //可以獲取插入后的主鍵值
            System.out.println(employee.getId());
            sqlSession.commit();
        }finally {
            //關閉sqlSession
            sqlSession.close();
        }
    }

刪除和修改

public interface EmployeeMapper {

    Long updateEmp(Employee employee);

    Boolean deleteEmpById(Integer id);

}

    <update id="updateEmp">
        UPDATE tbl_employee
        SET last_name=#{name},
            email=#{email},
            gender=#{gender}
        WHERE id = #{id}
    </update>

    <delete id="deleteEmpById">
        delete from tbl_employee where id = #{id}
    </delete>

    @Test
    public void updateEmp() throws IOException {
        //讀取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        //創建sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //獲取sqlSession實例，能直接執行已經映射的sql語句
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //執行查詢方法
        try {
            EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
            Employee employee = new Employee(17,"天使",'0',"[e-mail]");
            Long l = mapper.updateEmp(employee);
            System.out.println(l);
            sqlSession.commit();
        }finally {
            //關閉sqlSession
            sqlSession.close();
        }
    }

    @Test
    public void deleteEmpById() throws IOException {
        //讀取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        //創建sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        //獲取sqlSession實例，能直接執行已經映射的sql語句
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //執行查詢方法
        try {
            EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
            Boolean b = mapper.deleteEmpById(17);
            System.out.println(b);
            sqlSession.commit();
        }finally {
            //關閉sqlSession
            sqlSession.close();
        }
    }