Mybatis 核心组件

package com.learn.ssm.chapter3.pojo;

public class Role {
    private Long id;
    private String roleName;
    private String note;

    //如果你没有写任何构造函数，Java 会自动生成一个无参构造函数。
    //public Role(){}

    public Long getId() {
        return id;
    }

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

    public String getRoleName() {
        return roleName;
    }

    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }

    public String getNote() {
        return note;
    }

    public void setNote(String note) {
        this.note = note;
    }
}

package com.learn.ssm.chapter3.mapper;

import com.learn.ssm.chapter3.pojo.Role;
import java.util.List;

public interface RoleMapper {
    public int insertRole(Role role);
    public int deleteRole(Long id);
    public int updateRole(Role role);
    public Role getRole(Long id);
    public List<Role> findRoles(String roleName);
}

package com.learn.ssm.chapter3.utils;

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 SqlSessionFactoryUtils {

    private final static Class<SqlSessionFactoryUtils> LOCK = SqlSessionFactoryUtils.class;

    // 构造函数
    private SqlSessionFactoryUtils(){}

    // 单例模式
    private static SqlSessionFactory sqlSessionFactory = null;
    public static SqlSessionFactory getSqlSessionFactory() {
        synchronized (LOCK) {
            if(sqlSessionFactory != null) {
                return sqlSessionFactory;
            }

            // XML配置方式 实例化SqlSessionFactory
            String resource = "mybatis-config.xml";
            InputStream inputStream;
            try {
                inputStream = Resources.getResourceAsStream(resource);
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sqlSessionFactory;
    }

    public static SqlSession openSqlSession() {
        if(sqlSessionFactory == null) {
            getSqlSessionFactory();
        }
        return sqlSessionFactory.openSession();
    }

}

package com.learn.ssm.chapter3.main;

import com.learn.ssm.chapter3.mapper.RoleMapper;
import com.learn.ssm.chapter3.pojo.Role;
import com.learn.ssm.chapter3.utils.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        testRoleMapper();
    }

    private static void testRoleMapper() {
        Logger logger = Logger.getLogger(Main.class);
        SqlSession sqlSession = null;
        try {
            sqlSession = SqlSessionFactoryUtils.openSqlSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);

            Role role = new Role();
            role.setId(1L);
            role.setRoleName("Admin");
            role.setNote("System role");
            int num = roleMapper.insertRole(role);
            logger.info(num);//1

            Role role1 = roleMapper.getRole(1L);
            logger.info(role1);//com.learn.ssm.chapter3.pojo.Role@551a20d6

            role1.setRoleName("Administrator");
            num = roleMapper.updateRole(role1);
            logger.info(num);//1

            Role role2 = new Role();
            role2.setId(2L);
            role2.setRoleName("Visitor");
            role2.setNote("Unregistered");
            num = roleMapper.insertRole(role2);
            logger.info(num);//1

            List<Role> roles = roleMapper.findRoles("i");
            logger.info(roles);
            // [com.learn.ssm.chapter3.pojo.Role@7a11c4c7, com.learn.ssm.chapter3.pojo.Role@4cc547a]

            //提交事务
            sqlSession.commit();
        } catch (Exception e) {
            if(sqlSession != null) {
                sqlSession.rollback();
            }
            e.printStackTrace();
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
}

public static SqlSessionFactory getSqlSessionFactory2() {
  synchronized (LOCK) {
    // 数据库连接池信息
    PooledDataSource dataSource = new PooledDataSource();
    dataSource.setDriver("com.mysql.jdbc.Driver");
    dataSource.setUsername("root");
    dataSource.setPassword("123456");
    dataSource.setUrl("jdbc:mysql://localhost:3306/chapter3");
    dataSource.setDefaultAutoCommit(false);
    // 采用MyBatis的JDBC事务方式
    TransactionFactory transactionFactory = new JdbcTransactionFactory();
    Environment environment = new Environment("development", transactionFactory, dataSource);
    // 创建Configuration对象
    Configuration configuration = new Configuration(environment);
    // 注册一个MyBatis上下文别名
    configuration.getTypeAliasRegistry().registerAlias("role", Role.class);
    // 加入一个映射器
    configuration.addMapper(RoleMapper.class);
    configuration.addMapper(RoleMapper2.class);
    // 使用SqlSessionFactoryBuilder构建SqlSessionFactory
    sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
    return sqlSessionFactory;
  }
}

package com.learn.ssm.chapter3.mapper;

import org.apache.ibatis.annotations.Select;

import com.learn.ssm.chapter3.pojo.Role;

public interface RoleMapper2 {
	
	@Select("select id, role_name as roleName, note from t_role where id=#{id}")
	public Role getRole(Long id);
}

Role role = (Role)sqlSession.
selectOne("com.learn.ssm.chapter3.mapper.RoleMapper.getRole", 1L); 

Role role = (Role)sqlSession.selectOne("getRole", 1L);