Mybatis学习日志第一天

积累知识，胜过积蓄金银！毕竟在##column_title##开发的过程中，会遇到各种各样的问题，往往都是一些细节知识点还没有掌握好而导致的，因此基础知识点的积累是很重要的。下面本文《Mybatis学习日志第一天》，就带大家讲解一下MySQL、Java知识点，若是你对本文感兴趣，或者是想搞懂其中某个知识点，就请你继续往下看吧~

1.配置

• jdk8（jdk1.7以上均可）
• Maven 3.6.3
• MySQL 5.5 （mysql5.6以上均可）
• 官网文档： https://mybatis.org/mybatis-3/zh/getting-started.html

配置pom文档

<?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><!-- 父工程--><groupid>org.example</groupid><artifactid>Mybatis-Study</artifactid><packaging>pom</packaging><version>1.0-SNAPSHOT</version><modules><module>mybatis-01</module></modules><!-- 导入依赖--><dependencies><dependency><!-- 导入数据库依赖--><groupid>mysql</groupid><artifactid>mysql-connector-java</artifactid><version>5.1.49</version></dependency><!-- 导入Mybatis依赖--><dependency><groupid>org.mybatis</groupid><artifactid>mybatis</artifactid><version>3.5.2</version></dependency><!-- 导入Junit依赖--><dependency><groupid>junit</groupid><artifactid>junit</artifactid><version>4.12</version></dependency></dependencies><!-- maven无法读取src目录下的配置文件，加入下面代码保证maven能读取到Usermapper.xmi--><build><resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources></build></project>

2.连接数据库

在resources下创建一个叫mybatis-config.xml文件

<?xml version="1.0" encoding="UTF-8" ?><configuration><environments default="development"><environment id="development"><transactionmanager type="JDBC"></transactionmanager><datasource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"></property><property name="url" value="jdbc:mysql://localhost:3306/mybaits?useSSL=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT"></property><property name="username" value="root"></property><property name="password" value="root"></property></datasource></environment></environments><mappers><mapper resource="com/kuang/dao/UserMapper.xml"></mapper></mappers></configuration>

注意：手动连接数据库可能出现时区不对的情况

在url3306后面加入/?serverTimezone=GMT即可

3.创建类和接口，编写代码

3.1 mybatisUtils类

package com.kuang.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.jdbc.SQL;
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;
public class MybatisUtils {
 private  static SqlSessionFactory sqlSessionFactory;
 static {
 try {
 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。org.apache.ibatis.session.SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。
 public static SqlSession getSqlSession(){
 return sqlSessionFactory.openSession();
 }
}

3.2实体类

package com.kuang.pojo;
public class User {
 private int id;
 private String name;
 private String password;
 public User() {
 }
 public User(int id, String name, String password) {
 this.id = id;
 this.name = name;
 this.password = password;
 }
 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 getPassword() {
 return password;
 }
 public void setPassword(String password) {
 this.password = password;
 }
 @Override
 public String toString() {
 return "User{" +
 "id=" + id +
 ", name='" + name + ''' +
 ", password='" + password + ''' +
 '}'; }
}

3.3接口

package com.kuang.dao;
import com.kuang.pojo.User;
import java.util.List;
public interface UserDao {
 List<user>getUserList();
}</user>

3.4 接口实现类（写在xml文件中）

<?xml version="1.0" encoding="UTF-8" ?><mapper namespace="com.kuang.dao.UserDao"><select id="getUserList" resulttype="com.kuang.pojo.User">
 select * from mybaits.user;
  </select></mapper>

每一个xml文件都需要在mybatis-config的mappers中配置

<mappers><mapper resource="com/kuang/dao/UserMapper.xml"></mapper></mappers>
#### 3.5测试类

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(){
SqlSession sqlSession = MybatisUtils.getSqlSession();
UserDao userDao = sqlSession.getMapper(UserDao.class);
List userList = userDao.getUserList();
for (User user : userList) {
System.out.println(user);
}
sqlSession.close();
}
}

## 4.测试结果
![image.png](/img/bVcKWcF)
附数据库语句
![image.png](/img/bVcKWcM)

好了，本文到此结束，带大家了解了《Mybatis学习日志第一天》，希望本文对你有所帮助！关注golang学习网公众号，给大家分享更多数据库知识！