mybatis
什么是MyBatis?
MyBatis是一款优秀的持久层框架，用于简化JDBC开发
MyBatis本是Apache的一个开源项目iBatis,.2010年这个项目由apache software
foundation迁移到了google code,并且改名为MyBatis。2013年11月迁移到Github
官网
mybatis快速入门
导入mybatis
<dependencies>
<dependency>
<groupId>org.mybatisgroupId>
<artifactId>mybatisartifactId>
<version>3.5.5version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>5.1.45version>
dependency>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>3.8.2version>
<scope>testscope>
dependency>
<dependency>
<groupId>org.slf4jgroupId>
<artifactId>slf4j-apiartifactId>
<version>1.7.16version>
dependency>
<dependency>
<groupId>ch.qos.logbackgroupId>
<artifactId>logback-coreartifactId>
<version>1.2.3version>
dependency>
<dependency>
<groupId>ch.qos.logbackgroupId>
<artifactId>logback-classicartifactId>
<version>1.2.3version>
dependency>
dependencies>
1.创建user表，添加数据
CREATE DATABASE mybatis;
USE mybatis;
DROP TABLE IF EXISTS tb_user;
CREATE TABLE tb_user(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(20),
PASSWORD VARCHAR(20),
gender VARCHAR(20),
addr VARCHAR(30)
);
ALTER DATABASE mybatis CHARACTER SET utf8;
ALTER TABLE tb_user CHARACTER SET utf8;
INSERT INTO tb_user VALUES(1,'zhangsan','123','男','北京');
INSERT INTO tb_user VALUES(2,'李四','234','女','天津');
INSERT INTO tb_user VALUES(3,'王五','11','男','西安');
SELECT * FROM tb_user
2.创建模块，导入坐标
在 main 目录下的 resoures 配置文件目录下创建一个名为 logback.xml 的配置文件，粘贴一下内容：
<configuration>
<appender name="Console" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>【%level】 %blue(%d{HH:mm:ss.SSS}) %cyan(【%thread】) %boldGreen(%logger{15}) - %msg %npattern>
encoder>
appender>
<logger name="com.itheima" level="DEBUG" additivity="false">
<appender-ref ref="Console"/>
logger>
<root level="DEBUG">
<appender-ref ref="Console"/>
root>
configuration>
3.编写MyBatis核心配置文件->替换连接信息解决硬编码问题
在 main 目录下的 resoures 配置文件目录下创建一个名为 mybatis-config.xml 的配置文件，内容 在MyBatis官网
模板
DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<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 resource="org/mybatis/example/BlogMapper.xml"/>
mappers>
configuration>
修改后
DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false"/>
<property name="username" value="root"/>
<property name="password" value="lqx"/>
dataSource>
environment>
environments>
<mappers>
<mapper resource="UserMapper.xml"/>
mappers>
configuration>
4.编写SQL映射文件->统一管理sq语句，解决硬编码问题
在 main 目录下的 resoures 配置文件目录下创建一个名为 UserMapper.xml 的配置文件，内容在MyBatis官网
模板
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper">
<select id="selectBlog" resultType="Blog">
select * from Blog where id = #{id}
select>
mapper>
修改后
DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="test">
<select id="selectAll" resultType="com.lqx.pojo.User">
select * from tb_user;
select>
mapper>
5.编码
1.定义P0J0类
package com.lqx.pojo;
public class User {
private Integer id;
private String username;
private String PASSWORD;
private String gender;
private String addr;
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;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", PASSWORD='" + PASSWORD + '\'' +
", gender='" + gender + '\'' +
", addr='" + addr + '\'' +
'}';
}
}
2.加载核心配置文件，获取SqlSessionFactory对象
3.获取SqlSession对象，执行SQL语句
4.释放资源
package com.lqx;
import com.lqx.pojo.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.IOException;
import java.io.InputStream;
import java.util.List;
public class MyBatisDemo {
public static void main(String[] args) throws IOException {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
List<User> users = sqlSession.selectList("test.selectAll");
System.out.println(users);
sqlSession.close();
}
}