创建最简单的mybatis-maven应用-基于xml的实现

使用sqlyou在mysql的自带test库创建一张表，sql脚本如下

USE test;
CREATE TABLE product(
id INT(11) NOT NULL AUTO_INCREMENT,
product_name VARCHAR(200)NOT NULL,
store INT(11),
created DATE DEFAULT NULL,
updated DATE DEFAULT NULL,
PRIMARY KEY(id)
)DEFAULT CHARSET=utf8;

INSERT INTO product VALUES
(NULL,'apple',50,NOW(),NOW()),
(NULL,'pear',60,NOW(),NOW());

创建后表如图

创建maven项目

项目结构如下

pom.xml

<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.mybatis</groupId>
    <artifactId>mybatis-basic</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.8</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>
    </dependencies>
</project>

ProductMapper.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">
<!--mybatis中的映射文件 -->
<!--定义一个sql查询，sql查询必须有一个id,其中resultType表示查询结果会封装到对应的map类型中,一行记录对应一个map -->
<mapper namespace="com.project.dao.ProductDao">
    <select id="findAll" resultType="map">
        select * from product
    </select>
</mapper>

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>
    <!--配置开发环境 -->
    <environments default="development">
        <environment id="development">
            <!--事务管理环境 -->
            <transactionManager type="JDBC" />
            <!--配置数据源 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql:///test" />
                <property name="username" value="root" />
                <property name="password" value="g" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/ProductMapper.xml" />
    </mappers>
</configuration>

TestProduct.java

package com.project.test;

import java.io.IOException;
import java.util.List;
import java.util.Map;

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 TestProduct {
    private  static SqlSessionFactory factory;
    public static void init() throws IOException{
        factory=new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
    }
    public static void main(String[] args) {
        
        try {
            init();
            SqlSession session=factory.openSession();
            List<Map<String,Object>>list=session.selectList("com.project.dao.ProductDao.findAll");
            System.out.println(list);
            //一行记录映射为一个map(映射(封装)过程底层实现)
            //多行记录映射为多个map
            //多个map再存储到list集合
            session.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        
        
    }
}

运行结果

[{id=1, store=50, updated=2019-03-11, created=2019-03-11, product_name=apple}, {id=2, store=60, updated=2019-03-11, created=2019-03-11, product_name=pear}]