springBoot详细讲解使用mybaties案例-Java开发

MyBatis本是apache的一个开源项目iBatis，2010年这个项目由apachesoftwarefoundation迁移到了googlecode，并且改名为MyBatis。2013年11月迁移到Github。iBATIS一词来源于“internet”和“abatis”的组合，是一个基于Java的持久层框架

首先创建springBoot项目,jdk选择1.8

然后倒入mybaties的相关依赖

我们用的springBoot，当然spring全家桶里面含有mybaties，所以我们直接使用升级版的mybaties-plus。

引入这3个

lombok省的我每次创建对象，都需要get、set方法，以及toString

(IDEA里面也要安装lombok插件-》file->setting->plugin->搜索lombok安装，完后重启idea，这样lombok在idea中不报错）

mybatis-plus，mybaties的相关jar

mysql-connector-java 基本的jdbc驱动链接mysql，mybatis也要依赖他

	<properties>
		<java.version>1.8</java.version>
		<mybatis-plus.version>3.4.2</mybatis-plus.version>
	</properties>
    <dependency>
		<groupId>com.baomidou</groupId>
		<artifactId>mybatis-plus-boot-starter</artifactId>
		<version>${mybatis-plus.version}</version>
	</dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.18.4</version>
			<scope>provided</scope>
		</dependency>

然后像我这样，假设我们要搭建一个非常2的大工程，建立这几个目录和文件

controller->TestController.java(class)

mapper->TestMapper.java（interface)

service->impl->TestServiceImpl.java(class)

service->TestService.java(interface)

resources->mapper->TestMapper.xml(映射xml)

接下来我们需要一个SqlSessionFactory，去解析一个个sql.xml。

而sqlSessionFactory，由SqlSessionFactoryBuilder 构建，构建一个SqlSessionFactoryBuilder ，需要链接mysql的账号密码地址。所以要读取你的账号密码，那在resource目录下创建一个xml用于他去读取。

我在resources下的mapper里面创建一个mybaties-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="192.168.19.88"/>
                <property name="username" value="m11"/>
                <property name="password" value="m11@2022"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/TestMapper.xml"/>
    </mappers>
</configuration>

创建一个domain包，用来与mysql做相关映射,我在里面创建了一个实体类，与数据库做映射

@Data的就是我第一次导入的那个包，能够自动通过@Data注解，生成这个实体类的get、set方法以及toString方法。

package com.example.demo.domain;
import lombok.Data;
@Data
public class BZGG {
    String req_date;
    String stock_code;
    String stock_name;
    double fNextIncrease;
    double fNextAvgIncrease;
    String updatetime;
    public BZGG(String req_date, String stock_code, String stock_name, double fNextIncrease, double fNextAvgIncrease, String updatetime) {
        this.req_date = req_date;
        this.stock_code = stock_code;
        this.stock_name = stock_name;
        this.fNextIncrease = fNextIncrease;
        this.fNextAvgIncrease = fNextAvgIncrease;
        this.updatetime = updatetime;
    }
    public BZGG() {
    }
}

在mapper中的TestMapper中编写一个地址，并且加上Mapper映射

package com.example.demo.mapper;
import com.example.demo.domain.BZGG;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper
public interface TestMapper {
    List<BZGG> getBZGGonTime(String req_date);
}

mybaties的代码流程图

resources中的sql配置(TestMapper.xml)

<?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.example.demo.mapper.TestMapper">
    <select id="getBZGGonTime" resultType="com.example.demo.domain.BZGG">
        select * from   db_guoyuan.t_longhubang_stock_bzgg where req_date = #{req_date}
    </select>
</mapper>

controller层代码(你到时候可以自己分离service)，为了突出mybaties暂时写到一起了

package com.example.demo.controller;
import com.example.demo.domain.BZGG;
import com.example.demo.mapper.TestMapper;
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.springframework.web.bind.annotation.*;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
@RestController
public class TestController {
    @RequestMapping(value = "/Test", method = RequestMethod.GET)
    @ResponseBody
    public String getDemo(@RequestParam("num") int i) {
        String resource = "mapper/mybatis-config.xml";
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        TestMapper mapper = sqlSession.getMapper(TestMapper.class);
        List<BZGG> bzgGonTime = mapper.getBZGGonTime("2022-04-08");
        return bzgGonTime.toString();
    }
}

另外SpringApplication启动类，因为导入了mybaties，所以要启动时加载某个类，否则会出现url找不到等错误。

将@springBootApplication改成下面的

@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class, DataSourceTransactionManagerAutoConfiguration.class })

package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
//在启动类的@SpringBootApplication加上
//避免冲突，加入exclude
@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class, DataSourceTransactionManagerAutoConfiguration.class })
public class DemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}
}

测试:

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