MyBatis基于注解实现

项目框架

pom.xml导入各种依赖

   <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.20</version>
            </dependency>
    </dependencies>

resources中写MyBatis配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/my2?useSSl=true&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="1234"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper class="A.Mapper"/>
    </mappers>
</configuration>

A包中:
类:
User:实体类

package A;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Books {
    private int bookId;
    private String bookName;
    private String bookCounts;
}

MybatisUtils:MyBatis工具实现类

package A;

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 java.io.IOException;
import java.io.InputStream;

public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
    static  {
        String resource = "mybatis-config.xml";
             InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            System.out.println("错误");
        }
       sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }
    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }

}

可以直接用,这个类基本不会变。
接口:
Mapper:写要用到的方法,在其上方用注解实现数据库的语句

package A;

import org.apache.ibatis.annotations.*;

import java.util.List;
import java.util.Map;

public interface Mapper{
    //查询全部用户
    @Select("select * from user")
    List<User> getUserList();
    @Select("select * from user where name like #{value}")
    List<User> getUserLike(String value);
    //根据ID查询用户
    @Select("select * from user where id=#{id}")
    User getUserById(int id);
    //增加一个用户
    @Insert("insert into user values (#{id},#{name},#{pwd})")
    int addUser(User user);
    //万能的Map
    @Insert("insert into user(id,name) values (#{id},#{name})")
    int addUser1(@Param("id") int id,@Param("name") String name);
    //修改用户
    @Update("update user set name=#{name},pwd=#{pwd} where id=#{id}")
    int updateUser(User user);
    //删除用户
    @Delete("delete from user where id=#{id} and name=#{name}")
    int deleteUser(@Param("id") int id, @Param("name") String name);
}

注意要把这个配置到MyBatis配置文件中

    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>

放置在MyBatis配置文件中,具体位置请看resources中

Test包:
Test类:测试类

import A.Mapper;
import A.MybatisUtils;
import A.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Text {
    @Test
    public void test(){
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        Mapper mapper= (Mapper) sqlSession.getMapper(Mapper.class);
        List<User> list=mapper.getUserList();
        for (User user : list) {
            System.out.println(user);
        }
    }
    @Test
    public void test1(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        Mapper mapper=sqlSession.getMapper(Mapper.class);
        User user=mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }
    @Test
    public void test2(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        Mapper mapper=sqlSession.getMapper(Mapper.class);
        int res=mapper.addUser(new User(5,"张三","1234"));
        if(res>0) {
            System.out.print("插入成功");
            sqlSession.commit(); //提交事务
        }
        sqlSession.close();
    }
    @Test
    public void test3(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        Mapper mapper=sqlSession.getMapper(Mapper.class);
        int res=mapper.updateUser(new User(2,"张三","1234"));
        if(res>0) {
            System.out.print("修改成功");
            sqlSession.commit(); //提交事务
        }
        sqlSession.close();
    }
    @Test
    public void test4(){
        SqlSession sqlSession=MybatisUtils.getSqlSession();
        Mapper mapper=sqlSession.getMapper(Mapper.class);
        int res=mapper.deleteUser( 2,"张三");
        if(res>0) {
            System.out.print("删除成功");
            sqlSession.commit(); //提交事务
        }
        sqlSession.close();
    }
    @Test
    public void test5(){
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        Mapper mapper= (Mapper) sqlSession.getMapper(Mapper.class);
        List <User> list=mapper.getUserLike("张%");
        for (User user : list) {
            System.out.println(user);
        }
    }
}

数据库中表的创建

CREATE TABLE `user` (
  `id` INT NOT NULL ,
  `name` VARCHAR(40) DEFAULT NULL,
   `pwd` VARCHAR(40) DEFAULT NULL,
   PRIMARY KEY(id)
) ENGINE=INNODB DEFAULT CHARSET=utf8;

程序运行图

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