Mybatis获取与实践

Mybatis

如何获得Mybatis

• Maven

  • https://mvnrepository.com/artifact/org.mybatis/mybatis

  • <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.2</version>
    </dependency>
    

  • ​

• Github-下载地址：https://github.com/mybatis/mybatis-3/releases

• 中文文档：https://mybatis.net.cn/getting-started.html

新建项目

1. 新建一个普通的maven项目

2.删除src目录

3.导入maven依赖

<?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>com.chenteng</groupId>
    <artifactId>Mybatis-Study</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>mybatis-01</module>
    </modules>
    <!--导入依赖-->
    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.33</version>
        </dependency>
        <!--mybatis-->
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>
    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    </properties>

    <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>

创建一个模块

• 编写mybatis的核心文件

  

  <?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">
  <!--configuration核心配置文件-->
  <configuration>
      <environments default="development">
          <environment id="development">
              <transactionManager type="JDBC"/>
              <dataSource type="POOLED">
                  <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                  <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                  <property name="username" value="root"/>
                  <property name="password" value="123456"/>
              </dataSource>
          </environment>
      </environments>
      <mappers>
          <mapper resource="com/chenteng/dao/UserMapper.xml"/>
      </mappers>
  </configuration>
  

  ​

• 编写mybatis工具类

  

  package com.chenteng.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.InputStream;
  
  //SqlSessionFactory
  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 (Exception e) {
              e.printStackTrace();
          }
      }
  
      public static SqlSession getSqlSession(){
          return sqlSessionFactory.openSession();
      }
  

  }

  
  ​
  
  

编写代码

• 实现类

  package com.chenteng.pojo;
  
  //实体类
  public class User {
      private int id;
      private String name;
      private String pwd;
  
      public User() {
      }
  
      public User(int id, String name, String pwd) {
          this.id = id;
          this.name = name;
          this.pwd = pwd;
      }
  
      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 getPwd() {
          return pwd;
      }
  
      public void setPwd(String pwd) {
          this.pwd = pwd;
      }
  
      @Override
      public String toString() {
          return "User{" +
                  "id=" + id +
                  ", name='" + name + '\'' +
                  ", pwd='" + pwd + '\'' +
                  '}';
      }
  }
  
  

  ​

• Dao接口

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

  ​

• 接口实现类

  <?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">
  <!--namespace绑定一个对应的Dao/Mapper接口-->
  <mapper namespace="com.chenteng.dao.UserDao">
      <select id="getUserList" resultType="com.chenteng.pojo.User">
          select * from mybatis.user;
      </select>
  </mapper>
  

  ​

测试

注意点：

pom.xml配置resource，来防止我们资源导出失败的问题

 <!--    在build中配置resources ， 来防止我们资源导出失败的问题-->
    <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>
<!--    在build中配置resources ， 来防止我们资源导出失败的问题-->

• junit测试

package com.chenteng.dao;

import com.chenteng.pojo.User;
import com.chenteng.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<User> userList = userDao.getUserList();

        for (User user : userList) {
            System.out.println(user);
        }

        sqlSession.close();
    }
}