3.2 Mybatis快速入门

package com.itheima.pojo;
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;
import java.util.List;
public class MyBatisDemo {
    public static void main(String[] args) throws Exception {
        // 1. 加载mybatis的核心配置文件，获取SqlSessionFactory （sql会话工厂）
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 2. 获取SqlSession对象，用它来执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 3. 执行sql
        // 由于里面的sql语句是查询所有字段 ：select * from tb_user;， 所以要用selectList的API，查询一个就用selectone
        List<User> users = sqlSession.selectList("test.selectAll");// 参数是 空间名.标识名(id)
        // 打印查到的字段数据集合
        System.out.println(users);
        // 4.释放资源
        sqlSession.close();
    }
}

package com.itheima.pojo;
public class User {
   private Integer  id;
   private String  username;
   private String  password;
   private String  gender;
   private String  addr;
    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 getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public String getAddr() {
        return addr;
    }
    public void setAddr(String addr) {
        this.addr = addr;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", gender='" + gender + '\'' +
                ", addr='" + addr + '\'' +
                '}';
    }
}