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

<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&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@NoArgsConstructorpublic 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

查询所有用户

解梦吧