MyBatis数据库连接配置示例

一、Mybatis 和 Spring Mybatis 的关系

1、什么是 MyBatis？

​ MyBatis 是一款优秀的持久层框架，它支持自定义 SQL、存储过程以及高级映射。MyBatis 免除了几乎所有的 JDBC 代码以及设置参数和获取结果集的工作。MyBatis 可以通过简单的 XML 或注解来配置和映射原始类型、接口和 Java POJO（Plain Old Java Objects，普通老式 Java 对象）为数据库中的记录。

2、什么是 MyBatis-Spring？

​ MyBatis-Spring 会帮助你将 MyBatis 代码无缝地整合到 Spring 中。它将允许 MyBatis 参与到 Spring 的事务管理之中，创建映射器 mapper 和 SqlSession 并注入到 bean 中，以及将 Mybatis 的异常转换为 Spring 的 DataAccessException。最终，可以做到应用代码不依赖于 MyBatis，Spring 或 MyBatis-Spring。

开始学习时，要注意这两者的关系和区别：

3、MyBatis数据库连接配置示例

1)、POM依赖

    <properties>
        <mysql.version>5.1.38</mysql.version>
        <mybatis.version>3.5.2</mybatis.version>
        <junit.version>4.12</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>${mybatis.version}</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
        </dependency>
    </dependencies>

    <build>
        <!--资源文件管理-->
        <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>
    </build>

2)、数据连接配置

<!--文件：mybatis-config.xml-->
<configuration>
    <properties resource="./db.properties">
        <property name="jdbc-driver" value=""/>
        <property name="jdbc-url" value=""/>
        <property name="username" value=""/>
        <property name="password" value=""/>
    </properties>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc-driver}"/>
                <property name="url" value="${jdbc-url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/tonghua/dao/UserInfoMapper.xml"/>
    </mappers>
</configuration>

#文件：db.properties
jdbc-driver=com.mysql.jdbc.Driver
jdbc-url=jdbc:mysql://localhost/test?useSSL=true&useUnicode=true&characterEncoding=UTF-8
username=usertest
password=123456

3)、Mapper文件：

UserInfoMapper.java

package com.tonghua.dao;

import com.tonghua.pojo.UserInfo;
import java.util.List;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserInfoMapper {

    List<UserInfo> selectUserList();
}

UserInfoMapper.xml

<?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">
<mapper namespace="com.tonghua.dao.UserInfoMapper">
    <select id="selectUserList" resultType="com.tonghua.pojo.UserInfo">
    select * from userinfo;
  </select>
</mapper>

4)、实体类

package com.tonghua.pojo;

public class UserInfo {

    private int id;
    private String username;
    private String gender;

    public UserInfo(int id, String username, String gender) {
        this.id = id;
        this.username = username;
        this.gender = gender;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    @Override
    public String toString() {
        return "UserInfo{" +
            "id=" + id +
            ", username='" + username + '\'' +
            ", gender='" + gender + '\'' +
            '}';
    }
}

5)、工具类（创建SqlSession）

package com.tonghua.utils;

import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

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();
        }
    }

    public static SqlSession getSqlSession() {
        return sqlSessionFactory.openSession();
    }
}

6)、单元测试

UserInfoDaoTest.java

package com.tonghua.dao;

import com.tonghua.pojo.UserInfo;
import com.tonghua.utils.MybatisUtils;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

public class UserInfoDaoTest {

    @Test
    public void test() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        UserInfoMapper userInfoMapper = sqlSession.getMapper(UserInfoMapper.class);
        List<UserInfo> userList = userInfoMapper.selectUserList();

        for (UserInfo userInfo : userList) {
            System.out.println(userInfo);
        }

        sqlSession.close();
    }

}

7)、目录结构图

这是mybatis的一种连接方式，测试通过