Mybatis环境搭建
1.搭建数据库
2.新建项目
2.1新建y一个普通项目
2.2删除src目录(父工程)
2.3导入 maven依赖
<!--导入依赖-->
<dependencies>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
<!--mybatis-->
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<!--junit-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
3.创建一个模块
3.1编写mybatis配置文件
<!--核心配置文件-->
<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/mybatis?useSSL=true&serverTimezone=UTC&useUnicode=true&characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<!--每一个mapper.xml(dao层实现类)都需要在Mybatis核心配置文件中注册-->
<mappers>
<mapper resource="com/king/dao/UserMapper.xml"/>
</mappers>
</configuration>
3.2编写mybatis工具类
//工厂模式是为了生产产品的,当前就是sqlSessionFactory生产sqlSession //sqlSessionFactory--->sqlSession public class MybatisUtils { private static SqlSessionFactory sqlSessionFactory; static { try { //使用Mybatis第一步,获取sqlSessionFacter对象 String resource = "mybatis-config.xml"; 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(){ return sqlSessionFactory.openSession(); } }
3.3编写实体类
package com.king.pojo; //实体类 public class User { private Integer id; private String name; private String pwd; public User() { } public User(Integer id, String name, String pwd) { this.id = id; this.name = name; this.pwd = pwd; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getPwd() { return pwd; } public void setPwd(String pwd) { this.pwd = pwd; } @Override public String toString() { return "User{" + "id=" + id + ", name='" + name + '\'' + ", pwd='" + pwd + '\'' + '}'; } }
3.4 编写User接口
//官方文档中Mapper代替了Dao public interface UserDao { List<User> getUserList (); }
3.5,配置接口实现配置(UserMapper.xml)
<!--namespace(命名空间),绑定一个对应的Dao/Mapper接口--> <mapper namespace="com.king.dao.UserDao"> <!--查询语句--> <!--id相当于接口实现类重写方法的名字--> <!--resultType相当于一个结果集--> <select id="getUserList" resultType="com.king.pojo.User"> select * from mybatis.user; </select>c
3.6 junit测试
public class UserDaoTest { @Test public void test(){ //第一步:获得SqlSession对象 SqlSession sqlSession = MybatisUtils.getSqlSession(); //方式一:getMapper UserDao userDao = sqlSession.getMapper(UserDao.class); List<User> userList = userDao.getUserList(); for (User user : userList) { System.out.println(user); } //关闭SqlSession sqlSession.close(); } }
问题1:在idea的集成开发环境中,除resources外,其他包中是不能解析.xml文件的,
解决:在pom.xml中注入依赖
<build> <resources> <!--将java代码目录中的xml输出,默认不输出除resources目录外的xml文件,--> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> </resource> </resources> </build>
结果