SQL:
CREATE TABLE `tb_user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(20) DEFAULT NULL,
`password` varchar(20) DEFAULT NULL,
`gender` char(1) DEFAULT NULL,
`addr` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8
INSERT INTO tb_user VALUES (1,'zhangsan','123','男','北京');
INSERT INTO tb_user VALUES (2,'李四','111','女','上海');
INSERT INTO tb_user VALUES (3,'王五','122','男','河北');
创建Maven项目:
项目结构:
pom.xml:
<dependencies>
<!-- mybatis的依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<!-- mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
<!-- junit单元测试-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
java下创建pojo包,pojo包下创建User.java:
public class User {
private Integer id;
private String username;
private String password;
private String gender;
private String addr;
//getter&setter
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;
}
// toString
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", gender='" + gender + '\'' +
", addr='" + addr + '\'' +
'}';
}
}
resource下新建mybatis-config.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"https://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!-- 数据库连接信息-->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<!-- 加载SQL映射文件路径-->
<mappers>
<mapper resource="UserMapper.xml"/>
</mappers>
</configuration>
新建mapper包,包下新建UserMapper接口。
import pojo.User;
import java.util.List;
public interface UserMapper {
List<User> selectAll();
}
resource下新建UserMapper.xml映射.
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="testmapper"> <!--名称空间-->
<select id="selectAll" resultType="pojo.User"><!--id:唯一标识 resultType:返回结果的类型-->
select * from tb_user;
</select>
</mapper>
java下创建测试类test.java:
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 pojo.User;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
public class test {
public static void main(String[] args) throws IOException {
//1.加载mybatis的核心配置文件,获取sqlSessionFactory
String resource = "mybatis-config.xml";//定义配置文件路径
InputStream inputStream = Resources.getResourceAsStream(resource);//输入流进行资源加载,传入字符串返回输入流
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,自动封装结果集
List<User> users = sqlSession.selectList("testmapper.selectAll");
System.out.println(users);
//4.释放资源
sqlSession.close();
}
}
在test.java类中启动运行:
运行成功!