Mybatis入门教程，实现数据库简单增删改查

首先，我们在数据库中创建一个表，如图

接下来，我们创建一个maven项目
点击next


点击finish

在新建的maven项目的pom.xml文件中导入相关jar包

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
    </dependencies>

创建并编写MyBatis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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/cloudhospital?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="167833712"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/ltz/dao/UserMapper.xml"/>
    </mappers>
</configuration>

接下来创建实体类，首先在java文件夹下创建包

创建User类


编写Mapper接口类

编写增删改查方法

然后在dao包下编写Mapper.xml配置文件

<?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.ltz.dao.UserMapper">

</mapper>

在Mapper.xml中编写sql语句，先实现对所有用户的查询

编写sqlSessionFactory封装类

private static SqlSessionFactory sqlSessionFactory;
    static{

        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }

在test包下创建测试类进行测试

@Test
    public void test(){
        SqlSession sqlSession= MybatisUtils.getSqlSession();
        UserMapper usermapper=sqlSession.getMapper(UserMapper.class);
        List<User> u=usermapper.getUserList();

        for(User user:u){
            System.out.println(user);
        }
        sqlSession.close();
    }

但此时运行程序可能会报错，还需在pom.xml文件中加如下代码解决Maven静态资源过滤问题

<build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

现在运行测试类，查询全部用户成功！

查询指定用户，修改用户信息，删除用户，添加用户功能的实现只需在Mapper.xml中编写相应的sql语句即可，大大减少了代码冗余，下一章我们再来具体实现。

本文地址：https://blog.csdn.net/ltz777/article/details/109275102