Mybatis入门(一)环境搭建
2024-09-07 01:48:52
MyBatis 是一款优秀的持久层框架,它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息,将接口和 Java 的 POJOs(Plain Ordinary Java Object,普通的 Java对象)映射成数据库中的记录。
1、个人感觉还是跟着官方文档走稍微稳妥一些
1.1、准备maven库,Mysql5.7,和IDEA
准备maven库:
<dependencies>
<!--Mysql驱动-->
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.18</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-->
<!-- https://mvnrepository.com/artifact/junit/junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency> <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.10</version>
<scope>provided</scope>
</dependency>
</dependencies>
还有资源过滤:
<!--maven由于他的约定大于配置,我们之后可以能遇到我们写的配置文件,无法被处理或生效问题,解决方案-->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
2、开始搭建:
先去Mysql里创建一个user表:
查看表里的东西等一下要核对:
新建maven项目
在pom里面导入所需要的库:
<?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>org.example</groupId>
<artifactId>MybatisTest02</artifactId>
<version>1.0-SNAPSHOT</version> <dependencies>
<!--导入MySQL包/核心-->
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.18</version>
</dependency> <!--导入Mybatis包/核心-->
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.3</version>
</dependency> <!--导入junit测试包-->
<!-- https://mvnrepository.com/artifact/junit/junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency> </dependencies> <!--maven由于他的约定大于配置,我们之后可以能遇到我们写的配置文件,无法被处理或生效问题,解决方案-->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build> </project>
根据官方文档所需要一个xml核心配置文件和一个java核心配置类:
在resources新建一个xml文件起名为mybatis-config把官方文档的xml配置复制过来:
<?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核心配置类-->
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!--数据库jdbc包-->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<!--数据库的url地址,serverTimezone=UTC设置时区,UseUnicode=true&characterEncoding=UTF-8设置编码格式不然会乱码-->
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&UseUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC"/>
<!--数据库的账号-->
<property name="username" value="root"/>
<!--数据库的密码-->
<property name="password" value="root"/>
</dataSource>
</environment>
</environments> </configuration>
再把SqlSessionFactory,封装成一个工具类这样就可以方便调用
package com.hdlf.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;
//工具类
public class Mybatisconfig { private static SqlSessionFactory sqlSessionFactory; static{
try {
//使用Mybatis第一步,获取sqlSessionFactory对象
String resource = "mybatis-config.xml";//这个文件是可以直接读的。
InputStream inputStream = Resources.getResourceAsStream(resource);//获取配置文件,就是在resource下的文件
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
} //既然有了sqlSessionFactory,顾名思义,我们就可以从中获得SqlSession
//SqlSession完全包含了面向数据库执行SQL命令所需的所有方法
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
数据库表创建好之后,使用IDEA连接:
然后在新建一个实体类命名为User,里面的变量名字必须和mysql里创建表里面的键值名一样:
package com.hdlf.pojo; public class User {
private int id;
private String name;
private String pwe; @Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", pwe='" + pwe + '\'' +
'}';
} public User() {
} public User(int id, String name, String pwe) {
this.id = id;
this.name = name;
this.pwe = pwe;
} 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 getPwe() {
return pwe;
} public void setPwe(String pwe) {
this.pwe = pwe;
}
}
新建一个dao层Mapper接口命名为UserMaper:
package com.hdlf.dao; import com.hdlf.pojo.User; import java.util.List; public interface UserMapper { List<User> getUser();
}
然后再新建一个UserMapper.xml的配置文件:
这个可以去官网上复制
<?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">
<!--绑定UserMapper接口,大白话就是实现UserMapper这个接口的功能-->
<mapper namespace="com.hdlf.dao.UserMapper">
<!--id就是UserMapper里的方法名字,里面写执行MySQL的命令 resultType返回的类型-->
<select id="getUser" resultType="com.hdlf.pojo.User">
SELECT * FROM mybatis.user
</select>
</mapper>
在Test文件里新建一个测试类:
package com.hdlf.dao; import com.hdlf.pojo.User;
import com.hdlf.utils.Mybatisconfig;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test; import java.util.List; public class UserMapperTest {
@Test
public void test(){ //第一步,获得sqlsession对象
SqlSession sqlSession = Mybatisconfig.getSqlSession();
//执行sql
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
List<User> s = mapper.getUser(); for (User user:s){
System.out.println(user);
}
//关闭sqlSession
sqlSession.close();
}
}
目录是这样的:
运行之后会报错:
显示绑定异常
原因是没有把UserMapper.xml注解到Mybatis-config.xml文件夹里:
<?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核心配置类-->
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!--数据库jdbc包-->
<property name="driver" value="com.mysql.cj.jdbc.Driver"/>
<!--数据库的url地址,serverTimezone=UTC设置时区,UseUnicode=true&characterEncoding=UTF-8设置编码格式不然会乱码-->
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&UseUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC"/>
<!--数据库的账号-->
<property name="username" value="root"/>
<!--数据库的密码-->
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<!--注册UserMapper文件!!!-->
<mappers>
<mapper resource="com/hdlf/dao/UserMapper.xml"/>
</mappers>
</configuration>
在运行一下:
学起来很是复杂不过环境搭建好之后就非常轻松,一定要有耐心哦
最新文章
- Swift库运行崩溃
- 【09-04】java内部类学习笔记
- vim 编辑器的设置
- Windows 2003 服务器安全设置-批处理 (附参考链接)
- mongoDB操作命令及mongoDB的helper
- MySQL与Oracle主键Query性能测试结果
- Demo学习: CellDraw
- 关于iOS 5 Could not instantiate class named NSLayoutConstraint错误
- CodeForces 158C - Cd and pwd commands(模拟)
- C#语言和SQL Server 数据库处理
- tp5怎么实现搜索分页能保留搜索条件
- python 环境安装和卸载1
- Chrome开发者工具Debug入门
- [SDOi2012]吊灯
- PNG格式图片常见转换方法
- 22. Generate Parentheses(回溯)
- sqlserver变量的生周期
- will-change
- 【OpenCV-Python】-图像阀值
- mongoengine中queryset触发网络访问机制剖析
热门文章
- python setattr()、getattr()、hasattr() 函数用法介绍
- codeforces- Shortest path of the king
- [总结]一些 DP 优化方法
- 使用new时,会发生什么?
- DB开启 Service Broker,使用消息队列
- 刷题17. Letter Combinations of a Phone Number
- leetCode练题——9. Palindrome Number
- idea 设置自定义注释
- python合并大量ts文件成mp4格式(ps:上限是450,亲测)
- js前台给echarts赋值