一、mybatis的环境搭建
1.创建maven工程并导入坐标。
2.创建实体类和dao的接口。
3.创建mybatis的主配置文件mybatis-config.xml。
4.创建映射配置文件IUserDaoMapper.xml。
二、环境搭建的注意事项
1.mybatis的映射配置文件位置必须和dao接口的包结构相同。
2.映射配置文件的mapper标签namespace
属性的取值必须是dao接口的全限定类名
3.映射配置文件的操作配置(select),id的属性的取值必须是dao接口的方法名
当我们遵守了以上几点,我们在开发中就无需再写dao的实现类。
1.在pom.xml中的<version>
下先写导包方式:
<packaging>jar</packaging>
2.去maven仓库网址中找到mybatis的依赖坐标并添加
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
3.创建数据库的配置文件dbconfig.properties:
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/eesy
username=root
password=123456
4.创建一个mybatis-config.xml文件。
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--mybatis的主配置文件-->
<configuration>
<!--导入配置数据库的配置文件-->
<properties resource="dbconfig.properties"></properties>
<!--配置环境-->
<environments default="mysql">
<!--配置mysql的环境-->
<environment id="mysql">
<!--配置事务的类型-->
<transactionManager type="JDBC"></transactionManager>
<!--配置数据源(连接池)-->
<dataSource type="POOLED">
<!--配置连接数据库的基本信息-->
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper class="net/togogo/dao/IUserDaoMapper.xml"></mapper>
</mappers>
</configuration>
5.根据数据表创建bean类和dao接口
数据表:
bean类(User):
package net.togogo.bean;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable {
private Integer id;
private String username;
private Date birthday;
private String address;
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 Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", birthday=" + birthday +
", address='" + address + '\'' +
'}';
}
}
IUserDao接口方法:
package net.togogo.dao;
import net.togogo.bean.User;
import java.util.List;
/**
* 用户的持久层接口
*/
public interface IUserDao {
/**
* 查询所有操作
* @return
*/
List<User> findAll();
}
6.创建接口的配置文件IUserDao.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="net.togogo.dao.IUserDao">
<select id="findAll" resultType="net.togogo.bean.User">
select * from user
</select>
</mapper>
7.测试类mybatisTest
a.读取配置文件
b.创建SqlSessionFactory工厂
c.创建SqlSession
d.创建Dao接口的代理对象
e.执行dao中的方法
f.释放资源
package net.togogo;
import net.togogo.bean.User;
import net.togogo.dao.IUserDao;
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;
/**
* mybatis的入门案例
*
*/
public class mybatisTest {
public static void main(String[] args) throws IOException {
//1.读取配置文件
InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
//2.创建SqlSessionFactory工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
//3.使用工厂生产SqlSession对象
SqlSession session = factory.openSession();
//4.使用SqlSession创建Dao接口的代理对象
IUserDao iUserDao = session.getMapper(IUserDao.class);
//5.使用代理对象执行方法
List<User> users = iUserDao.findAll();
for (User user : users) {
System.out.println(user);
}
//6.释放资源
session.close();
in.close();
}
}
8.运行结果