mybatis註解版延遲加載、立即加載、一級緩存、二級緩存

1.延遲加載和立即加載

public class AccountTest {
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IAccountDao accountDao;

    @Before
    public  void init()throws Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        factory = new SqlSessionFactoryBuilder().build(in);
        session = factory.openSession();
        accountDao = session.getMapper(IAccountDao.class);
    }

    @After
    public  void destroy()throws  Exception{
        session.commit();
        session.close();
        in.close();
    }

    @Test
    public  void  testFindAll(){
        List<Account> accounts = accountDao.findAll();
        for(Account account : accounts){
            System.out.println("----每個賬戶的信息-----");
            System.out.println(account);
            System.out.println(account.getUser());
        }
    }

 

public class AnnotationCRUDTest {
    private InputStream in;
    private SqlSessionFactory factory;
    private SqlSession session;
    private IUserDao userDao;

    @Before
    public  void init()throws Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        factory = new SqlSessionFactoryBuilder().build(in);
        session = factory.openSession();
        userDao = session.getMapper(IUserDao.class);
    }

    @After
    public  void destroy()throws  Exception{
        session.commit();
        session.close();
        in.close();
    }

    @Test
    public  void  testFindAll(){
        List<User> users = userDao.findAll();
        for(User user : users){
            System.out.println("---每個用戶的信息----");
            System.out.println(user);
            System.out.println(user.getAccounts());
        }
    }

    @Test
    public void testFindOne(){
        User user = userDao.findById(57);
        System.out.println(user);
    }


    @Test
    public  void testFindByName(){
        List<User> users = userDao.findUserByName("%mybatis%");
        for(User user : users){
            System.out.println(user);
        }
    }


}

public class Account implements Serializable {

    private Integer id;
    private Integer uid;
    private Double money;

    //多對一（mybatis中稱之爲一對一）的映射：一個賬戶只能屬於一個用戶
    private User user;

}

public class User implements Serializable{

    private Integer userId;
    private String userName;
    private String userAddress;
    private String userSex;
    private Date userBirthday;

    //一對多關係映射：一個用戶對應多個賬戶
    private List<Account> accounts;
}

public interface IAccountDao {

    /**
     * 查詢所有賬戶，並且獲取每個賬戶所屬的用戶信息
     * @return
     */
    @Select("select * from account")
    @Results(id="accountMap",value = {
            @Result(id=true,column = "id",property = "id"),
            @Result(column = "uid",property = "uid"),
            @Result(column = "money",property = "money"),
            @Result(property = "user",column = "uid",one=@One(select="com.itheima.dao.IUserDao.findById",fetchType= FetchType.EAGER))
    })
    List<Account> findAll();

    /**
     * 根據用戶id查詢賬戶信息
     * @param userId
     * @return
     */
    @Select("select * from account where uid = #{userId}")
    List<Account> findAccountByUid(Integer userId);
}

@CacheNamespace(blocking = true)
public interface IUserDao {

    /**
     * 查詢所有用戶
     * @return
     */
    @Select("select * from user")
    @Results(id="userMap",value={
            @Result(id=true,column = "id",property = "userId"),
            @Result(column = "username",property = "userName"),
            @Result(column = "address",property = "userAddress"),
            @Result(column = "sex",property = "userSex"),
            @Result(column = "birthday",property = "userBirthday"),
            @Result(property = "accounts",column = "id",
                    many = @Many(select = "com.itheima.dao.IAccountDao.findAccountByUid",
                                fetchType = FetchType.LAZY))
    })
    List<User> findAll();

    /**
     * 根據id查詢用戶
     * @param userId
     * @return
     */
    @Select("select * from user  where id=#{id} ")
    @ResultMap("userMap")
    User findById(Integer userId);

    /**
     * 根據用戶名稱模糊查詢
     * @param username
     * @return
     */
    @Select("select * from user where username like #{username} ")
    @ResultMap("userMap")
    List<User> findUserByName(String username);


}

public class SecondLevelCatchTest {

    private InputStream in;
    private SqlSessionFactory factory;


    @Before
    public  void init()throws Exception{
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        factory = new SqlSessionFactoryBuilder().build(in);

    }

    @After
    public  void destroy()throws  Exception{

        in.close();
    }

    @Test
    public void testFindOne(){
        SqlSession session = factory.openSession();
        IUserDao userDao = session.getMapper(IUserDao.class);
        User user = userDao.findById(49);
        System.out.println(user);

        session.close();//釋放一級緩存

        SqlSession session1 = factory.openSession();//再次打開session
        IUserDao userDao1 = session1.getMapper(IUserDao.class);
        User user1 = userDao1.findById(49);
        System.out.println(user1);


        session1.close();

    }
}