2.9 使用方式

新建maven项目

pom.xml

<?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>com.zsk</groupId>
    <artifactId>mybatis_test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>
        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>42.2.8</version>
        </dependency>
    </dependencies>


    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
            </plugin>
        </plugins>
        <!--配置资源目录-->
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.*</include>
                </includes>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.*</include>
                </includes>
            </resource>
            <!-- 打包时将jsp文件拷贝到META-INF目录下 -->
            <resource>
                <!-- 指定resources插件处理哪个目录下的资源文件 -->
                <directory>src/main/webapp</directory>
                <!--注意此次必须要放在此目录下才能被访问到 -->
                <targetPath>META-INF/resources</targetPath>
                <includes>
                    <include>**/*.*</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>
</project>

配置mybatis

• resources/jdbc.properties

driver=org.postgresql.Driver
url=jdbc:postgresql://localhost:5432/tao
username=zsk
password=zskroot

• resources/mybatis-config.xml

<?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>
    <properties resource='jdbc.properties'/>
    <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="mapper/UserMapper.xml"/>
    </mappers>
</configuration>

新建mapper

• com.zsk.model.User

package com.zsk.model;

/**
 * @description:
 * @author: zsk
 * @create: 2019-11-30 15:32
 **/
public class User
{
    private Long id;
    private String username;

    public Long getId()
    {
        return id;
    }

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

    public String getUsername()
    {
        return username;
    }

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

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

• com.zsk.dao.UserMapper

package com.zsk.dao;

import com.zsk.model.User;

/**
 * @description:
 * @author: zsk
 * @create: 2019-11-30 15:31
 **/
public interface UserMapper
{
    User getById(Long id);
}

• mapper/UserMapper.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.zsk.dao.UserMapper">
    <select id="getById" resultType="com.zsk.model.User" parameterType="java.lang.Long">
        select * from tb_user where id = #{id}
    </select>
</mapper>

测试

• Main

import com.zsk.dao.UserMapper;
import com.zsk.model.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;

/**
 * @description:
 * @author: zsk
 * @create: 2019-11-30 15:28
 **/
public class Main
{
    public static void main(String[] args) throws IOException
    {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        try (SqlSession session = sqlSessionFactory.openSession())
        {
            UserMapper mapper = session.getMapper(UserMapper.class);
            User user = mapper.getById(7L);
            System.out.println(user);
        }
    }
}

项目结构

参考

• mybatis – MyBatis 3 | Introduction