基于maven的mybatis项目

1.maven配置

    <dependencies>


        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>


        <!--mysql依赖-->
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.22</version>
        </dependency>

        <!--Junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

2.创建一个模块，继承父工程的maven依赖

• 编写mybatis的核心配置文件

<?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/mybatistest?setTimeZone=UTF&amp;userSSl=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
<mapper>XXXX</mapper>


</configuration>

• 编写mybatis的工具类

package utils;

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;

//每个基于 MyBatis 的应用都是以一个 SqlSessionFactory 的实例为核心的。
// SqlSessionFactory 的实例可以通过 SqlSessionFactoryBuilder 获得。
// 而 SqlSessionFactoryBuilder 则可以从 XML 配置文件或一个预先配置的 Configuration 实例来构建出 SqlSessionFactory 实例。
public class MybatisUtil {

    private  static  SqlSessionFactory sqlSessionFactory=null;
    static {
        String resource = "org/mybatis/example/mybatis-config.xml";

        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
         sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    public static SqlSession getSqlSession(){
        //从sqlSessionFactory中获取到SqlSession



        return  sqlSessionFactory.openSession();
    }

}

3.编写代码

pojo层实体类

package pojo;

public class User {
    private  int id;
    private String username;
    private String pwd;

    public User(int id, String username, String pwd) {
        this.id = id;
        this.username = username;
        this.pwd = pwd;
    }

    public User() {
    }

    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public String getPwd() {
        return pwd;
    }

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

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

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}

dao接口类

package dao;

import pojo.User;

import java.util.List;

//应该是UserMapper
public interface UserDao {
   List<User> getUser();

}

dao实现类

<?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="dao.UserDao">
    <select id="getUser" resultType="pojo.User">
    select * from user
  </select>
</mapper>

4.测试
1.代码编写

package dao;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import pojo.User;
import utils.MybatisUtil;

import java.util.List;

public class UserDaotest {

    @Test
    public void test(){
        //获得sqlSession
        SqlSession sqlSession = MybatisUtil.getSqlSession();

        //获得执行的方法
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        //遍历结果集
        List<User> user = mapper.getUser();
        for(User us:user)
            System.out.println(user);

        System.out.println(user.size());
        //关闭sqlSession
        sqlSession.close();
    }
}

2.异常处理

解决：resource默认回去resouces文件下寻找mybatis-config.xml文件

2.maven资源过滤问题

<!--解决资源过滤的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>