The first Mybatis program
Ideas: build the environment -> import Mybatis -> write code -> test
1. Build the environment
1.1 Build the database
(1) Create a new database - mybatis
(2) Create a new user table in the mybatis database
create table `user`(
`id` int(20) not null ,
`name` varchar(30) default null,
`pwd` varchar(30) default null,
primary key(`id`)
)engine=INNODB default charset=utf8;
insert into `user` (`id`,`name`,`pwd`) values
(1,'婉婉','1123'),
(2,'小红','1123'),
(3,'晓晓','1123')
1.2 New project
Change the maven warehouse address: modify the location of the maven warehouse in the idea
1.3 delete src
1.4 Import dependencies
<!--mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.40</version>
</dependency>
<!--mybatis -->
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.3</version>
</dependency>
<!--junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13.2</version>
<scope>test</scope>
</dependency>
If the version is red, just click maven on the right and refresh
1.5 Create a new model
1.6 Connecting to the database
1. Open the database
2. Click the database on the right side of the idea
1.7 Writing configuration files
Create a configuration file of mybatis-config.xml under the resource under the project
url:数据库连接地址
useSSL=false 安全连接,只有当由安全证书时才能用true
useUnicode=true Unicode编码
characterEncoding=UTF-8 字符为UTF-8格式
serverTimezone=GMT 设置时区
&符要用转义字符&
<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--configuratio是核心配置文件-->
<configuration>
<environments default="development">
<environment id="development">
<!-- transactionManager：事务管理-->
<transactionManager type="JDBC"/>
<!-- dataSource中包含数据库相关配置-->
<dataSource type="POOLED">
<!-- driver：数据库驱动com.mysql.jdbc.Driver -->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<!-- url:数据库连接地址
useSSL=false 安全连接,只有当由安全证书时才能用true
useUnicode=true Unicode编码
characterEncoding=UTF-8 字符为UTF-8格式
serverTimezone=GMT 设置时区
&符要用转义字符&
-->
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&useEncoding=false&characterEncoding=UTF-8&serverTimezone=GMT"/>
<!-- username:用户名-->
<property name="username" value="root"/>
<!-- password：数据库连接密码-->
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!-- 每个Mapper.xml都需要在Mybatis核心配置文件中注册-->
<mappers>
<mapper resource="com/kuang/dao/UserMapper.xml"/>
</mappers>
</configuration>
1.8 Write mybatis tool class
1. Create a new package com.kuang.dao and com.kuang.utils
1.9 Write mybatis tool class
Create a new tool class MybatisUtils under the com.kuang.utils package
package com.kuang.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;
//sqlSessionFactory用来构建sqlSession
public class MybatisUtils {
//提升SqlSessionFactory的作用域
private static SqlSessionFactory sqlSessionFactory;
static{
try {
// 使用Mybatis第一步获取sqlSessionFactory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。
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
1.10 Writing code
- entity class
package com.kuang.pojo;
//实体类对象
public class User {
private int id;
private String name;
private String pwd;
public int getId() {
return id;
}
public void setId(int 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 + '\'' +
'}';
}
}
- Dao interface
package com.kuang.dao;
import com.kuang.pojo.User;
import java.util.List;
public interface UserDao {
// 返回所有用户信息
List<User> getUserList();
}
- The implementation class of the Dao interface is
converted from the original UserDaoImpl to a Mapper configuration file
<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.kuang.dao.UserDao">
<!-- select:查询语句
id：对应方法名
-->
<!-- resultType：返回一个结果
resultMap:返回结果集
后面的值要写全限定名：即包名+类名
-->
<select id="getUserList" resultType="com.kuang.pojo.User">
select * from user;
</select>
</mapper>
1.11 Testing
junit test
package com.kuang.dao;
import com.kuang.pojo.User;
import com.kuang.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class UserDaoTest {
@Test
public void test(){
//第一步：获取SqlSession对象
SqlSession sqlSession = MybatisUtils.getSqlSession();
//执行Sql
// 方式一：getMapper（推荐使用）
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<User> userList = userDao.getUserList();
// 方式二：
// List<User> userList = sqlSession.selectList("com.kuang.dao.UserDao.getUserList");
for (User user:userList) {
System.out.println(user);
}
//关闭sqlSession
sqlSession.close();
}
}
result
