mybatis demo简单实现

开发工具：IDEA

开发步骤：

一、建立maven项目

    

<?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.jd.xia</groupId>
    <artifactId>test-ibatis</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>test-mybatis</module>
        <module>test-ibatis1</module>
    </modules>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.31</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.13.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.ibatis/ibatis-sqlmap -->
        <dependency>
            <groupId>org.apache.ibatis</groupId>
            <artifactId>ibatis-sqlmap</artifactId>
            <version>2.3.4.726</version>
        </dependency>


    </dependencies>

</project>

二、建立mybatis模块

mybatis通过xml配置文件与Mapper接口建立映射关系，在进行数据库操作室，只需声明Mapper接口对象，java虚拟机会在运行过程中利用反射机制根据xml配置文件建立Mapper的实体类。

package com.mongo.mybatis;

import java.util.List;

public interface UserMapper {

    List<User> selectById(Integer id);
}

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/test" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="userMapper.xml"/>
    </mappers>

</configuration>

<?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.mongo.mybatis.UserMapper">

    <!--
        根据id查询得到一个user对象
     -->
    <select id="selectById" parameterType="int"
            resultType="com.mongo.mybatis.User">
        select * from user where id=#{id}
    </select>
</mapper>

package com.mongo.mybatis;

public class User {
    private Integer id;
    private String username;

    public User(Integer id, String username) {
        this.id = id;
        this.username = username;
    }

    public User() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer 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 + '\'' +
                '}';
    }
}

package com.mongo.mybatis;

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;
import java.util.List;

public class Main {

    public static void main(String[] args) throws IOException {
        //mybatis的配置文件
        String resource = "mybatis-config.xml";
        //使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
        InputStream is = Main.class.getClassLoader().getResourceAsStream(resource);
        //构建sqlSession的工厂
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
        //使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）
        //Reader reader = Resources.getResourceAsReader(resource);
        //构建sqlSession的工厂
        //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //创建能执行映射文件中sql的sqlSession
        SqlSession session = sessionFactory.openSession();
        /**
         * 映射sql的标识字符串，
         * me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
         * getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
         */
        //String statement = "com.mongo.mybatis.User";//映射sql的标识字符串

        UserMapper userMapper = session.getMapper(UserMapper.class);

        //执行查询返回一个唯一user对象的sql
        List<User> users = userMapper.selectById(1);
        System.out.println(users);

        session.close();
    }

}

github:https://github.com/xhyflowcloud/ORM.git