mybatis工程搭建

准备数据源

 

示例

drop database if exists mybatis_demo;

create database mybatis_demo;

use mybatis_demo;

create table user (

id int auto_increment primary key,

username varchar(20),

age int,

score int

);

insert into user (id, username, age, score) values

(1,'peter', 18, 100), (2,'pedro', 24, 200),

(3,'jerry', 28, 500), (4,'mike', 12, 300),

(5,'tom', 27, 1000);

引入MySQL驱动包

<dependencies>

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->

    <dependency>

        <groupId>mysql</groupId>

        <artifactId>mysql-connector-java</artifactId>

        <version>8.0.23</version>

    </dependency>

</dependencies>

public class JDBCDemo {

public static void main(String[] args) throws Exception {

Class.forName("com.mysql.cj.jdbc.Driver");

Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatis_demo", "root", "root");

PreparedStatement preparedStatement = connection.prepareStatement("select * from user WHERE id = ?");

preparedStatement.setInt(1, 1);

ResultSet resultSet = preparedStatement.executeQuery();

while (resultSet.next()) {

System.out.println("username: " + resultSet.getString("username"));

System.out.println("age: " + resultSet.getString("age"));

}

resultSet.close();

preparedStatement.close();

connection.close();

}

}

 

<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->

<dependency>

<groupId>org.mybatis</groupId>

<artifactId>mybatis</artifactId>

<version>3.5.6</version>

</dependency>

<!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->

<dependency>

<groupId>ch.qos.logback</groupId>

<artifactId>logback-classic</artifactId>

<version>1.3.0-alpha5</version>

<scope>test</scope>

</dependency>

用代码实现删除JDBC连接及操作数据库

 

@SuppressWarnings({"SqlResolve", "SqlNoDataSourceInspection", "Duplicates"})

public class StartNoXml {

    public static void main(String[] args) throws SQLException {

        JdbcTransactionFactory jdbcTransactionFactory = new JdbcTransactionFactory();

        PooledDataSource dataSource =

new PooledDataSource(

                "com.mysql.cj.jdbc.Driver", "jdbc:mysql://localhost:3306/mybatis_demo?useSSL=false",

                "root",

                "root");

Environment environment = new Environment.Builder("development")

                .transactionFactory(jdbcTransactionFactory)

                .dataSource(dataSource).build();

Configuration configuration = new Configuration(environment);

        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);

        SqlSession session = sqlSessionFactory.openSession();

PreparedStatement preStatement = session

.getConnection()

.prepareStatement("SELECT * FROM user WHERE id = ?");

preStatement.setInt(1, 1);

ResultSet result = preStatement.executeQuery();

while (result.next()) {

System.out.println("username: " + result.getString("username"));

System.out.println("age: " + result.getString("age"));

}

session.close();

}

}

 

引入MyBatis依赖

maven仓库查询网址：MavenRepository

• mybatis：MyBatis基础包
• logback-classic：日志依赖

<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.6</version>
</dependency>
<!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.3.0-alpha5</version>
    <scope>test</scope>
</dependency>

编程式配置方法

MyBatis官方文档中并未详细的介绍如何编程式使用MyBatis，因为编程式配置方法代码有点复杂

但在实际的开发中几乎没有机会去写这段代码，一般都是通过配置文件来拿到配置然后开启会话的

 

代码实现

删除JDBC连接及操作数据库：JDBCDemo.java

新建编程式配置文件：StartNoXml.java

 

@SuppressWarnings({"SqlResolve", "SqlNoDataSourceInspection", "Duplicates"})
public class StartNoXml {
    public static void main(String[] args) throws SQLException {
        // 准备jdbc事务类
        JdbcTransactionFactory jdbcTransactionFactory = new JdbcTransactionFactory();
        // 配置数据源
        PooledDataSource dataSource = new PooledDataSource(
                "com.mysql.cj.jdbc.Driver",
                "jdbc:mysql://localhost:3306/mybatis_demo?useSSL=false",
                "root",
                "root");
        // 配置环境，向环境中指定环境id、事务和数据源
        Environment environment = new Environment.Builder("development")
                .transactionFactory(jdbcTransactionFactory)
                .dataSource(dataSource).build();
        // 新建 MyBatis 配置类
        Configuration configuration = new Configuration(environment);
        // 得到 SqlSessionFactory 核心类
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
        // 开始一个 sql 会话
        SqlSession session = sqlSessionFactory.openSession();
        // 得到 sql 连接并运行 sql 语句
        PreparedStatement preStatement = session
                .getConnection()
                .prepareStatement("SELECT * FROM user WHERE id = ?");
        preStatement.setInt(1, 1);
        ResultSet result = preStatement.executeQuery();
        // 验证结果
        while (result.next()) {
            System.out.println("username: " + result.getString("username"));
            System.out.println("age: " + result.getString("age"));
        }
        // 关闭会话
        session.close();
    }
}

配置文件配置MyBatis

代码实现

在resources文件夹下新建配置文件：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>
    <!-- 环境变量 -->
    <environments default="development">
        <environment id="development">
            <!-- 事务管理器 -->
            <transactionManager type="JDBC"/>
            <!-- 数据源 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_demo?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
</configuration>