Mybatis目录
注解开发的crud
1.IUserDao接口中使用注解
2.测试类
注解开发的多表查询
多对一(一对一)
1.IAccountDao接口中使用注解
2.Account类中(从表类)
3.测试类
一对多(多对多)
1.IUserDao接口中使用注解
2.User类中(从表类)
注解开启二级缓存
注解开发的crud
1.IUserDao接口中使用注解
public interface IUserDao {
/**
* 查询所有用户
* @return
*/
@Select("select * from user")
List<User> findAll();
/**
* 保存用户
* @param user
*/
@Insert("insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday})")
void saveUser(User user);
/**
* 更新用户
* @param user
*/
@Update("update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id=#{id}")
void updateUser(User user);
/**
* 删除用户
* @param userId
*/
@Delete("delete from user where id=#{id} ")
void deleteUser(Integer userId);
/**
* 根据id查询用户
* @param userId
* @return
*/
@Select("select * from user where id=#{id} ")
User findById(Integer userId);
/**
* 根据用户名称模糊查询
* @param username
* @return
*/
// @Select("select * from user where username like #{username} ")
@Select("select * from user where username like '%${value}%' ")
List<User> findUserByName(String username);
/**
* 查询总用户数量
* @return
*/
@Select("select count(*) from user ")
int findTotalUser();
}
2.测试类
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 testSave(){
User user = new User();
user.setUsername("mybatis annotation");
user.setAddress("北京市昌平区");
userDao.saveUser(user);
}
@Test
public void testUpdate(){
User user = new User();
user.setId(57);
user.setUsername("mybatis annotation update");
user.setAddress("北京市海淀区");
user.setSex("男");
user.setBirthday(new Date());
userDao.updateUser(user);
}
@Test
public void testDelete(){
userDao.deleteUser(51);
}
@Test
public void testFindOne(){
User user = userDao.findById(57);
System.out.println(user);
}
@Test
public void testFindByName(){
// List<User> users = userDao.findUserByName("%mybatis%");
List<User> users = userDao.findUserByName("mybatis");
for(User user : users){
System.out.println(user);
}
}
@Test
public void testFindTotal(){
int total = userDao.findTotalUser();
System.out.println(total);
}
}
注解开发的多表查询
可以这么记忆:
你所需要对应的表是很多个注解用many
对应一个的话就用one
demo功能阐述
查询用户账户的时候 返回用户的信息
因为多个账户或者一个账户才对应一个用户
多对一(Mybatis中 一对一)
1.IAccountDao接口中使用注解
public interface IAccountDao {
/**
* 查询所有账户,并且获取每个账户所属的用户信息
* @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"),
//这个注解是引入主表 FetchType(加载时机) EAGER(立即加载)
@Result(property = "user",column = "uid",one=@One(select="com.itheima.dao.IUserDao.findById",fetchType= FetchType.EAGER))
})
List<Account> findAll();
/**
* 根据用户id查询账户信息
* @param userId
* @return
*/
@Select("select * from account where uid = #{userId}")
List<Account> findAccountByUid(Integer userId);
}
2.Account类中(从表类)
//多对一(mybatis中称之为一对一)的映射:一个账户只能属于一个用户
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
3.测试类
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("----每个账户的信息-----");
System.out.println(account);
System.out.println(account.getUser());
}
}
}
一对多(多对多)
查询用户信息的时候 返回用户的账户信息
因为一个用户对应多个用户的账户信息
使用的是延迟加载
1.IUserDao接口中使用注解
public interface IUserDao {
/**
* 查询所有用户
* @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();
/**
* 根据id查询用户
* @param userId
* @return
*/
@Select("select * from user where id=#{id} ")
@ResultMap("userMap")
User findById(Integer userId);
/**
* 根据用户名称模糊查询
* @param username
* @return
*/
@Select("select * from user where username like #{username} ")
@ResultMap("userMap")
List<User> findUserByName(String username);
}
2.User类中(从表类)
//一对多关系映射:一个用户对应多个账户
private List<Account> accounts;
public List<Account> getAccounts() {
return accounts;
}
public void setAccounts(List<Account> accounts) {
this.accounts = accounts;
}
注解开启二级缓存
哪个Dao接口需要就写在哪儿
@CacheNamespace(blocking = true) 位于到的顶部!!