MyBatis的注解开发

单表的CRUD注解开发：

User实体类：

package com.zyb.pojo;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
private Integer id;
private String username;
private String sex;
private String address;
private Date birthday;

    public User() {
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                ", birthday=" + birthday +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
}

UserDao:

package com.zyb.dao;

import com.zyb.pojo.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import java.util.List;

public interface UserDao {
   @Select("select * from my_user")
    List<User> selAllUsers();

   @Insert("insert into my_user(username,address,sex,birthday) values(#{username},#{address},#{sex},#{birthday}) ")
   void saveUser(User u);

   @Update("update my_user set username=#{username} where id=#{id}")
   void updateUser(User user);

   @Delete("delete from my_user where id=#{id}")
   void deleteUserById(int userId);

   @Select("select * from my_user where id=#{id}")
   User selUserById(int userId);

   @Select("select * from my_user where username like '%${value}%'")
//   @Select("select * from my_user where username like #{username}")
   List<User> selUserByName(String userName);

    @Select("select count(*) from my_user")
    int usersNum();
}

 

测试：

package com.zyb.test;

import com.zyb.dao.UserDao;
import com.zyb.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.Date;
import java.util.List;

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

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

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

    @Test
    public void testSelAllUsers(){
        List<User> users=userDao.selAllUsers();
        users.forEach(x-> System.out.println(x));
    }

    @Test
    public void testSaveUser(){
        User user= new User();
        user.setSex("男");
        user.setAddress("地球");
        user.setBirthday(new Date());
        user.setUsername("zhang");
        userDao.saveUser(user);
    }

    @Test
    public void testUpdateUser(){
       User user = new User();
       user.setId(58);
       user.setUsername("liu");
       user.setSex("女");
       userDao.updateUser(user);

    }

    @Test
    public void testDeleteUserById(){
        userDao.deleteUserById(58);
    }

    @Test
    public void testSelUserById(){
       User user= userDao.selUserById(52);
       System.out.println(user);
    }

    @Test
    public void testSelUserByName(){
        List<User> users=userDao.selUserByName("王");
        users.forEach(x-> System.out.println(x));
    }

    @Test
    public void testUsersNum(){
        int num=userDao.usersNum();
        System.out.println(num);
    }

}

 

多表注解操作：

逻辑：一个用户可以有多个账户，一个账户只能被一个用户拥有

User实体类多了一个：

 

新增的Account实体类：

package com.zyb.pojo;

import java.io.Serializable;

public class Account implements Serializable {
    private Integer id;
    private Integer uid;
    private Double money;
    private User user;

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }

    public Account() {
    }
}

AccountDao:

package com.zyb.dao;

import com.zyb.pojo.Account;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.mapping.FetchType;

import java.util.List;

public interface AccountDao {

    @Select("select * from my_account")
    @Results(id="accountMap",value = {
            @Result(property = "id",column = "id",id=true),
            @Result(property = "uid",column = "uid"),
            @Result(property = "money",column = "money"),
            @Result(property = "user",column = "uid",one = @One(select = "com.zyb.dao.UserDao.selUserById",fetchType= FetchType.EAGER))

    })
    List<Account> selAllAccounts2User();

    @Select("select * from my_account where uid=#{uid}")
    @ResultMap("accountMap")
    List<Account> selAccountsByUid();
}

UserDao:

package com.zyb.dao;

import com.zyb.pojo.User;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.mapping.FetchType;

import java.util.List;

public interface UserDao {
   @Select("select * from my_user")
   @Results(id="userMap" ,value={
           @Result(property = "userId",column="id" ,id=true),
           @Result(property = "userName",column="username"),
           @Result(property = "userAddress",column="address"),
           @Result(property = "userSex",column="sex"),
           @Result(property = "userBirthday",column="birthday"),
           @Result(property = "accounts",column = "id",many = @Many(select = "com.zyb.dao.AccountDao.selAccountsByUid",fetchType = FetchType.LAZY))

   })
    List<User> selAllUsers();


   @Select("select * from my_user where id=#{id}")
   @ResultMap(value = {"userMap"})
   User selUserById(int userId);


   @Select("select * from my_user where username like #{username}")
   @ResultMap(value = {"userMap"})
   List<User> selUserByName(String userName);

}

Dao层分析：

Results点进去的源码：

id属性、Result类型的value数组

 

 Result类型点进去的源码：

One或Many点进去的源码：

 

 注意在使用注解是mybatis-config.xml的配置