Mybatis框架
一、SSM的结构框图
二、目录
三、mybatis的环境搭建(使用的是idea)
第一步:创建一个maven的工程并导入jar包坐标
文件—新建—Maven–next—填写信息—finish—在pom.xml中写入代码
pom.xml:
jar包会自动导入
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.lwc</groupId>
<artifactId>day01_eeay-01mybatis</artifactId>
<version>1.0-SNAPSHOT</version>
<!-- 导入jar包-->
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.6</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.2</version>
</dependency>
</dependencies>
</project>
第二步:在MySQL里建表
第三步:创建实体类和dao的接口
实体类User:
package com.lwc.domain;
import java.io.Serializable;
import java.util.Date;
/**
* @Auther: Xinbai
* @Date:2020/5/3 19:05
*/
public class User implements Serializable {
private Integer id;
private String username;
private Date birthday;
private String sex;
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 getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
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 +
", sex='" + sex + '\'' +
", address='" + address + '\'' +
'}';
}
}
dao接口:
package com.lwc.Dao;
import com.lwc.domain.User;
import java.util.List;
/**
* @Auther: Xinbai
* @Date:2020/5/3 19:16
* 用户的持久层接口
*/
public interface UserDao {
/**
* 查询所有操作
*/
List<User> findAll();
}
第三步:创建mybatis的主配置文件
mybatis.xml:
<?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">
<configuration>
<!--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4个基本信息-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!--指定映射配置文件的位置,映射配置文件指的是每个dao独立的配置文件-->
<mappers>
<mapper resource="com/lwc/dao/UserDao.xml"/>
</mappers>
</configuration>
第四步:创建映射配置文件
UserDao.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.lwc.Dao.UserDao">
<!--配置查询所有-->
<select id="findAll" resultType="com.lwc.domain.User">
select *from user;
</select>
</mapper>
第五步:测试
package com.lwc.test;
import com.lwc.Dao.UserDao;
import com.lwc.domain.User;
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.InputStream;
import java.util.List;
/**
* @Auther: Xinbai
* @Date:2020/5/3 19:52
* mybatis 入门
*/
public class MybatisTest {
public static void main(String[] args) throws Exception {
//1.读取配置文件
InputStream in= Resources.getResourceAsStream("mybatis.xml");
//2.创建mybatis工厂模式
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
UserDao userDao=session.getMapper(UserDao.class);
//5.使用代理对象执行方法
List<User>users=userDao.findAll();
for (User user:users){
System.out.println(user);
}
//6.释放资源
session.close();
in.close();
}
}
四、结果图
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五、使用注解来配置
需改变mybatis.xml文件的配置、UserDao.java的配置,删除上面第四步的代码。其它不变也可以实现mybatis的配置。
mybatis.xml
<?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">
<configuration>
<!--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4个基本信息-->
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/eesy_mybatis"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!--指定映射配置文件的位置,映射配置文件指的是每个dao独立的配置文件
如果是用注解来配置的话,此处应该使用class属性指定被注解的dao权限定类名-->
<mappers>
<mapper class="com.lwc.Dao.UserDao"/>
</mappers>
</configuration>
UserDao:
package com.lwc.Dao;
import com.lwc.entity.User;
import org.apache.ibatis.annotations.Select;
import java.util.List;
/**
* @Auther: Xinbai
* @Date:2020/5/4 17:34
*/
public interface UserDao {
@Select("select *from user")
List<User> findAll();
}