用Maven创建一个MyBatis项目

用Maven创建一个MyBatis项目

新建项目

1. 

2. 

Maven中Web工程的标准目录

目录

• src

  • main
    • java[Sources] (存放类文件)
    • resources[Resources] (存放资源文件)
    • webapp(web项目目录)
      • WEB-INF
        • web.xml
  • test
    • java[Test] (测试类)

• pom.xml(项目依赖文件,Maven核心)

如何更改文件夹类型[]

File–>Project Structure–>Modules–>[Module名]–>Mark as

创建MyBatis项目

pom.xml

Maven仓库:https://mvnrepository.com/

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.20</version>
        </dependency>
    </dependencies>

创建实体类

package com.wjy.pojo;

public class User {
    int id;
    String username,password;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

创建Dao接口

package com.wjy.dao;

import java.util.List;

public interface UserMapper {
    public List findById(int id);
}

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">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://xxx.xxx.xxx.xxx:3306/test?characterEncoding=utf8&amp;useSSL=false&amp;serverTimezone=UTC&amp;allowPublicKeyRetrieval=true&amp;autoReconnect=true"/>
                <property name="username" value="xxxx"/>
                <property name="password" value="xxxx"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/UserMapper.xml"/>
        <!--映射文件路径-->
    </mappers>
</configuration>

在resources文件夹下创建mapper文件夹并在其中创建UserMapper.xml

resources/mapper/UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--
* mapper
	 * namespace:dao类路径
* select
	* id:方法名
	* parameterType:传入值类型
	* resultType:返回值类型
	* #{id}:值传入值名
-->
<mapper namespace="com.wjy.dao.UserMapper">
	<select id="findById" parameterType="int" resultType="com.wjy.pojo.User">
        select id,username,password from user where id=#{id}
    </select>
</mapper>

在test/java下编写测试类

import com.wjy.dao.UserMapper;
import com.wjy.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.Test;

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

public class UserTest {
    @Test
    public void find(){
        //定义读取文件名
        String resources = "mybatis-config.xml";
        //创建流
        Reader reader=null;
        try {
            //读取mybatis-config.xml文件到reader对象中
            reader= Resources.getResourceAsReader(resources);
        } catch (IOException e) {
            e.printStackTrace();
        }
        //初始化mybatis,创建SqlSessionFactory类的实例
        SqlSessionFactory sqlMapper=new SqlSessionFactoryBuilder().build(reader);
        //创建session实例
        SqlSession session=sqlMapper.openSession();
        //传入参数查询，返回结果
        UserMapper userMapper=session.getMapper(UserMapper.class);
        List<User> user=userMapper.findById(1);
        //输出结果
        System.out.println(user);
        //关闭session
        session.close();
    }
}

执行结果

成功返回对象

最终目录结构:

参考文章

https://www.cnblogs.com/wvae/p/9607684.html