mybatis入门

package com.xxxx.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 MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        String resource = "mybatis-config.xml";

        try {
            // 1.使用mybatis的第一步 --- 获取SqlSessionFactory实例对象
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例
     * SqlSession 提供了在数据库执行 SQL 命令所需的所有方法
     * 你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。
     */
    public static SqlSession getSqlSession() {
        //通过SqlSessionFactory打开数据库会话
        return sqlSessionFactory.openSession();
    }
}

package com.xxxx.pojo;
import java.sql.Date;

public class Book {
    private Integer book_id; // 图书编号
    private String name;   //书名
    private String author; //作者
    private String  publish; //出版社
    private String introduction; //简介
    private String language; //语言
    private double price; //价钱
    private Date pub_date; //出版日期
    private Integer class_id; //书籍类别
    private Integer number; //书籍数量

    public Book() {
    }

    public Book(Integer book_id, String name, String author, String publish, String introduction, String language, double price, Date pub_date, Integer class_id, Integer number) {
        this.book_id = book_id;
        this.name = name;
        this.author = author;
        this.publish = publish;
        this.introduction = introduction;
        this.language = language;
        this.price = price;
        this.pub_date = pub_date;
        this.class_id = class_id;
        this.number = number;
    }

      get/set、toString()  方法 

package com.xxxx.dao;

import com.xxxx.pojo.Book;
import org.apache.ibatis.annotations.Select;
import java.util.List;

public interface BookDao {
    // XML的语句映射方式
    public List<Book> getBooksAll(); //获取所有书籍信息

    // 基于注解的语句映射方式
    @Select("select * from book_info where book_id=#{book_id}")
    public Book getBookByID(int id);
}

package com.xxxx.dao;

import com.xxxx.pojo.Book;
import com.xxxx.utils.JsonModel;
import com.xxxx.utils.JsonUtil;
import com.xxxx.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;

public class BookDaoTest {
    @Test
    public void test() {
        // 1. 获得SqlSession
        SqlSession session = MybatisUtils.getSqlSession();
        // 2. 获得mapper，执行sql
        BookDao mapper = session.getMapper(BookDao.class);
        List<Book> list = mapper.getBooksAll();
        JsonModel<List<Book>> book = new JsonModel<>();
        book.setStatus(1);
        book.setMsg("success");
        book.setData(list);
        book.setTotal(list.size());
        System.out.println(JsonUtil.toJsonString(book));
        session.close();
    }

    @Test
    public void test1() {
        SqlSession session = MybatisUtils.getSqlSession();
        BookDao mapper = session.getMapper(BookDao.class);
        Book book = mapper.getBookByID(1);  // 查询id为1的书籍信息
        System.out.println(book);
        session.close();
    }
}

package com.xxxx.pojo;

import org.apache.ibatis.type.Alias;

@Alias("emp")
public class Emp {
    private Integer empno;
    private String ename;
    private String job;
    private String hiredate;
    private Double sal;
    private Integer deptno;

    get/set、toString()  方法
}

@Select("select * from test")
public List<Emp> listEmpAll();

@Test
public void test2() {
    SqlSession session = MybatisUtils.getSqlSession();
    BookDao mapper = session.getMapper(BookDao.class);
    List<Emp> list = mapper.listEmpAll();
    System.out.println(list);
    session.close();
}