使用MyBatis搭建一个访问mysql数据库的简单示例

MyBatis是一个支持普通SQL查询，存储过程和高级映射的优秀持久层框架。MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及对结果集的检索封装。MyBatis可以使用简单的XML或注解用于配置和原始映射，将接口和Java的POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录。

框架整体结构图：

关键代码介绍

1.ICatagoryOperation接口

public interface ICatagoryOperation {
    void inserteCatagory(Catagory catagory);

    Catagory getCatagorybyID(int id);
}

2.Catagory类

public class Catagory {
    private int id;
    private String name;

    private String description;

    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 getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Override
    public String toString() {
        return String.format("id:%d,name:%s,description:%s", id, name, description);
    }
}

3.MyBatisUtils类

public class MyBatisUtils {
    private static final String CONFIG_PATH = "config/mybatis_config.xml";

    /*
     * 获取数据库访问链接
     */
    public static SqlSession getSqlSession() {
        SqlSession session = null;
        try {
            InputStream stream = Resources.getResourceAsStream(CONFIG_PATH);
            // 可以根据配置的相应环境读取相应的数据库环境
            // SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(
            // stream, "development");
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(stream);
            session = factory.openSession();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        return session;
    }

    /*
     * 获取数据库访问链接
     */
    public static void closeSession(SqlSession session) {
        session.close();
    }
}

4.CatagoryMapper.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.franson.study.interfaces.ICatagoryOperation">
<!-- 此处的resultType就是对应刚刚你在typeAlias节点里面规定的别名 -->
    <select id="inserteCatagory" parameterType="Catagory">
       insert into tb_catagories(name,description) values(#{name},#{description})
    </select>
    <select id="getCatagorybyID" resultType="Catagory" parameterType="java.lang.Integer">
    select * from tb_catagories where id=#{id}
    </select>
</mapper>

5.mybatis_config.xml,核心配置文件

<?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>
    <typeAliases>
        <typeAlias type="com.franson.study.model.Catagory" alias="Catagory" />
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <!-- ?useUnicode=true&amp;characterEncoding=utf8为了支持中文数据的写入 -->
                <property name="url"
                    value="jdbc:mysql://127.0.0.1:3306/db_catagory?useUnicode=true&amp;characterEncoding=utf8" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/CatagoryMapper.xml" />
    </mappers>
</configuration>

6.TestMybatis测试入口类

public class TestMybatis {

    public static void main(String[] args) {
        addTest();
        getTest();
    }

    /*
     * 添加Catagory
     */
    static void addTest() {
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        ICatagoryOperation catagoryOperation = sqlSession.getMapper(ICatagoryOperation.class);
        Catagory item = new Catagory();
        item.setName("sql server");
        item.setDescription("sql server类");
        int result = catagoryOperation.inserteCatagory(item);
        if (result > 0) {
            sqlSession.commit();
            System.out.println("添加成功");
        } else
            sqlSession.rollback();
        MyBatisUtils.closeSession(sqlSession);
    }

    /*
     * 根据ID获取Catagory
     */
    static void getTest() {
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        ICatagoryOperation catagoryOperation = sqlSession.getMapper(ICatagoryOperation.class);
        System.out.println(catagoryOperation.getCatagorybyID(3).toString());
        MyBatisUtils.closeSession(sqlSession);
    }
}

7.测试运行结果