Mybatis入门

搭建环境

1.导入jar包和解决maven资源打包问题。

<dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>

        <!-- mysql的驱动 -->
        <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>
 <!-- 解决maven资源打包问题 -->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

2.核心配置文件 mybatis-conifg.xml 和 db.properties

<?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>

    <!--引入外部配置文件-->
    <properties resource="db.properties"/>

    <!--标准的日志工厂-->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <!--可以给实体类起别名-->
    <typeAliases>
        <package name="com.flyange.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
       
 <!--<mapper resource="com/flyange/dao/LawMapper.xml"/>-->

        <!--使用class配置注意
            1.接口和它的Mapper配置文件必须同名
            2.接口和它的Mapper配置文件必须在同一个包下
        -->
        <mapper class="com.flyange.dao.LawMapper"/>
    </mappers>
</configuration>

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/nutzfw-open?useSSL=false&useUnicode=true&characterEncoding=utf-8
username=root
password=root

3.编写公共类

package com.flyange.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 MyBatisUtils {

    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 getSessionFactory(){
        return sqlSessionFactory.openSession(true);
    }

}

4.编写实体类

package com.flyange.pojo;

public class LawInfo {
    private int id;
    private String law_title;
    private String law_time;
    private String law_type;
    private String ask_count;

    public LawInfo() {
    }

    public LawInfo(int id, String law_title, String law_time, String law_type, String ask_count) {
        this.id = id;
        this.law_title = law_title;
        this.law_time = law_time;
        this.law_type = law_type;
        this.ask_count = ask_count;
    }

    public int getId() {
        return id;
    }

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

    public String getLaw_title() {
        return law_title;
    }

    public void setLaw_title(String law_title) {
        this.law_title = law_title;
    }

    public String getLaw_time() {
        return law_time;
    }

    public void setLaw_time(String law_time) {
        this.law_time = law_time;
    }

    public String getLaw_type() {
        return law_type;
    }

    public void setLaw_type(String law_type) {
        this.law_type = law_type;
    }

    public String getAsk_count() {
        return ask_count;
    }

    public void setAsk_count(String ask_count) {
        this.ask_count = ask_count;
    }

    @Override
    public String toString() {
        return "LawInfo{" +
                "id=" + id +
                ", law_title='" + law_title + '\'' +
                ", law_time='" + law_time + '\'' +
                ", law_type='" + law_type + '\'' +
                ", ask_count='" + ask_count + '\'' +
                '}';
    }
}

5.编写接口和Mapper

package com.flyange.dao;

import com.flyange.pojo.LawInfo;

import java.util.List;

public interface LawMapper {
    List<LawInfo> getLawList();
}

<?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.flyange.dao.LawMapper">

    <select id="getLawList" resultType="LawInfo">
       select * from law_info
    </select>
</mapper>

6.测试

import com.flyange.dao.LawMapper;
import com.flyange.pojo.LawInfo;
import com.flyange.util.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class MybatisTest {

    @Test
    public void getData(){

        SqlSession sqlSession = MyBatisUtils.getSessionFactory();
        LawMapper lawDao = sqlSession.getMapper(LawMapper.class);

        List<LawInfo> lawList = lawDao.getLawList();
        for (LawInfo lawInfo : lawList) {
            System.out.println(lawInfo);
        }

        sqlSession.close();
    }
}