Mybatis配置文件(maven项目)

配置pom.xml依赖

<?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>test-sql</groupId>
    <artifactId>test-sql</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.9</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
    </dependencies>


</project>

在resource文件夹下面创建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>
    <environments default="development">
        <environment id="development">
            <!-- 使用JDBC事务管理器，目前由MyBatis管理 -->
            <transactionManager type="JDBC"/>
            <!--dataSource 指连接源配置，POOLED是JDBC连接对象的数据源连接池的实现-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="001122"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--这是告诉Mybatis区哪找持久化类的映射文件(xml映射文件)-->
        <mapper resource="mapper/User.xml"/>
    </mappers>
</configuration>

 为了能在控制台看到输出（如上所示），需要配置log4j.properties文件，和mybatis.xml配置文件同级

log4j.rootLogger=DEBUG, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender 
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 
log4j.appender.stdout.layout.ConversionPattern=%5p %d %C: %m%n

log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

数据库查询语句写在resource/mapper下的.xml，以用户的增删改查为例

<?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">
<!--namespace:用来隔离sql-->
<mapper namespace="mapper.User">
    <!--resultType指定返回数据的实体类型，parameterType指定输入数据类型-->
    <select id="searchById" parameterType="int" resultType="com.neuedu.pojo.User">
        select * from User where id = #{id}
    </select>

    <!-- concat用来拼接，%为通配符，这种方式可以防止sql注入-->
    <select id="findUserByName" resultType="com.neuedu.pojo.User" parameterType="string">
        select * from User where username like concat('%',#{info},'%');
    </select>

    <!-- insert 插入数据 只有parameterType输入参数
        useGeneratedKeys属性指定开启自动填充功能
        keyProperty属性用于指定生成的主键值填充到类的哪个属性上 -->
    <insert id="insertUser" parameterType="com.neuedu.pojo.User" useGeneratedKeys="true" keyProperty="id">
        insert into User values(null, #{username}, #{birthday}, #{sex}, #{address})
    </insert>

    <!-- update 同样只有输入参数parameterType-->
    <update id="updateUser" parameterType="com.neuedu.pojo.User">
        update User set username = #{username}, sex = #{sex}, birthday = #{birthday}, address = #{address}
        where id = #{id}
    </update>

    <!-- delete 也是输入参数 -->
    <delete id="deleteUser" parameterType="string">
        delete from User where username = #{username}
    </delete>
</mapper>

我们创建一个工具类，可以直接调用获取SqlSession

package com.neuedu.util;

import org.apache.ibatis.io.Resources;
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;

public class MyBatisUtil {

    private static SqlSessionFactory sessionFactory;

    static {

        try {
            //加载配置文件
            InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
            //创建sessionFactory对象
            sessionFactory = new SqlSessionFactoryBuilder().build(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //获取session对象
    public static SqlSession openSession() {
        return sessionFactory.openSession();
    }
}

我们在test/java目录下创建sessionTest，进行单元测试

package com.neuedu.test;
import com.neuedu.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

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

public class sessionTest {

    private SqlSession session;

    @Before
    public void init() throws IOException {
        //通过Resources类加载和读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");

        //根据配置文件的信息创建SqlSessionFactory对象
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);

        //通过SqlSessionFactory获取SqlSession对象
        session = sessionFactory.openSession();
    }

    //带一个参数
    @Test
    public void findUserById(){
        User u = session.selectOne("mapper.User.searchById", 1);
        System.out.println("findUserById" + u.toString());
    }

    //带一个参数
    @Test
    public void findUserByNameTest(){
        List<User> userList = session.selectList("mapper.User.findUserByName", "哈");
        System.out.println("findUserByNameTest" + userList.get(0).toString());
    }

    //插入数据
    @Test
    public void testInsertUser(){
        try {
            User user = new User(null, "嘿嘿嘿", "男", "2022-12-12", "东北大学");
            int rows = session.insert("mapper.User.insertUser", user);
            System.out.println(rows);
            session.commit();
        } catch (Exception e) {
            session.rollback();
        }
    }

    //修改数据
    @Test
    public void testUpdateUser(){
        try {
            User user = session.selectOne("mapper.User.searchById", 1);
            user.setAddress("西北大学");
            int rows = session.update("mapper.User.updateUser", user);
            System.out.println("testUpdateUser"+rows);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            System.out.println("fails");
        }
    }

    //删除数据
    @Test
    public void testDeleteUser() {
        try {
            int rows = session.delete("mapper.User.deleteUser", "嘿嘿嘿");
            System.out.println(rows);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            e.printStackTrace();
        }
    }



//    @Test
//    public void testSession(){
//        //输出session
//        System.out.println(session);
//        //输出session对应的Connection的连接
//        System.out.println(session.getConnection());
//    }

    @After
    public void destory(){
        //对连接进行关闭
        session.close();
    }
}

也可以新建一个test测试类，在测试类中写主函数，代码如下

//获取SqlSessionFactory对象
        String resource = "mybatis-config.xml";
        try{
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
            SqlSessionFactory sqlSessionFactory = builder.build(inputStream);

            SqlSession sqlSession = sqlSessionFactory.openSession();

            Object one = sqlSession.selectOne("searchById",1);
            System.out.println(one);
        } catch (IOException e) {
            e.printStackTrace();
        }