[六]SpringBoot 之 连接数据库(mybatis)

在进行配置之前首先要了解springboot是如何使用纯java代码方式初始化一个bean的

以前的版本是在xml中使用beans标签,在其里面配置bean,那么纯Java代码怎么实现呢?

答案就是使用@Configuration注解和@Bean,代码如下:当然搜资料过程中你会学习到其他的知识,并尝试使用

1.mybatis-spring-boot-stater的Maven依赖

<dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

        <dependency>
            <groupId>commons-dbcp</groupId>
            <artifactId>commons-dbcp</artifactId>
        </dependency>

2.配置数据源，这里使用的dbcp的数据源，具体大家可以看自己的情况来使用

在src/main/resource中，添加一个application.properties配置文件，这里面添加了一些数据库连接的信息

########################################################
###datasource
########################################################

spring.datasource.url = jdbc:mysql://123.206.228.200:3306/test

spring.datasource.username = shijunjie

spring.datasource.password = ******

spring.datasource.driverClassName = com.mysql.jdbc.Driver

spring.datasource.max-active=20

spring.datasource.max-idle=8

spring.datasource.max-maxWait=100

spring.datasource.min-idle=8

spring.datasource.initial-size=10

2.1注入数据源

package me.shijunjie.config;

import org.apache.commons.dbcp.BasicDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@PropertySource("classpath:application.properties")
public class DataSourceConfiguration {
    @Value("${spring.datasource.driverClassName}")
    private String driver;
    @Value("${spring.datasource.url}")
    private String url;
    @Value("${spring.datasource.username}")
    private String username;
    @Value("${spring.datasource.password}")
    private String password;
    @Value("${spring.datasource.max-active}")
    private int maxActive;
    @Value("${spring.datasource.max-idle}")
    private int maxIdel;
    @Value("${spring.datasource.max-maxWait}")
    private long maxWait;
    
    @Bean
    public BasicDataSource dataSource(){
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName(driver);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        dataSource.setMaxActive(maxActive);
        dataSource.setMaxIdle(maxIdel);
        dataSource.setMaxWait(maxWait);
        dataSource.setValidationQuery("SELECT 1");
        dataSource.setTestOnBorrow(true);
        return dataSource;
    }
}

2.2MyBatis的配置

package me.shijunjie.config;

import javax.sql.DataSource;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.transaction.annotation.TransactionManagementConfigurer;

@Configuration
//加上这个注解，使得支持事务
@EnableTransactionManagement
public class MybatisConfig implements TransactionManagementConfigurer {
    @Autowired
    private DataSource dataSource;

    @Override
    public PlatformTransactionManager annotationDrivenTransactionManager() {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactoryBean() {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        try {
            return bean.getObject();
        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }
    
    @Bean
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

2.3配置MyBatis配置文件的路径，这个配置需要与上面的配置分开来写，因为它们有着一个先后顺序

package me.shijunjie.config;

import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@AutoConfigureAfter(MybatisConfig.class)
public class MyBatisMapperScannerConfig {
    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        //获取之前注入的beanName为sqlSessionFactory的对象
        mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
        //指定xml配置文件的路径
        mapperScannerConfigurer.setBasePackage("me.shijunjie.dao");
        return mapperScannerConfigurer;
    }
}

2.4使用@Mapper注解来标识一个接口为MyBatis的接口，MyBatis会自动寻找这个接口

package me.shijunjie.dao;

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;

import me.shijunjie.entity.Demo2;

@Mapper
public interface DemoDao2{
    
    @Insert("insert into t_demo(tname) "+
            "values(#{name})")
    int save(Demo2  demo);
}

3.编写Controller 和 Service 以及实体类

编写实体类：

package me.shijunjie.entity;

public class Demo2 {

    public Demo2() {
    }

    public Demo2(long id, String name) {
        this.id = id;
        this.name = name;
    }

    private long id;

    private String name;

    public long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }


}

编写service和实现类：

package me.shijunjie.service;

import me.shijunjie.entity.Demo2;

public interface DemoService {
    public void save(Demo2 demo);
}

package me.shijunjie.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import me.shijunjie.dao.DemoDao2;
import me.shijunjie.entity.Demo2;
import me.shijunjie.service.DemoService;

@Service
public class DemoServiceImpl implements DemoService {

    @Autowired
    private DemoDao2 demoDao;

    public void save(Demo2 demo){
        demoDao.save(demo);
    }
}

编写Controller

package me.shijunjie.controller;

import javax.annotation.Resource;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import me.shijunjie.entity.Demo2;
import me.shijunjie.service.DemoService;

@RestController
@RequestMapping("/demo")
public class DemoController {

    @Resource
    private DemoService demoService;

    /**

     * 测试保存数据方法.

     * @return

     */

    @RequestMapping("/save")
    public String save(){
        Demo2 d = new Demo2();
        d.setName("Angel2");
        demoService.save(d);//保存数据.
        return "ok.DemoController.save";

    }
}

编写入口类

package me.shijunjie.controller;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.web.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.scheduling.annotation.EnableScheduling;

@ComponentScan(basePackages={"me.shijunjie"}) // 扫描该包路径下的所有spring组件
/*@EnableJpaRepositories("me.shijunjie.dao") // JPA扫描该包路径下的Repositorie
*//*@EntityScan("me.shijunjie.entity") // 扫描实体类
*/@SpringBootApplication
@EnableScheduling
public class App extends SpringBootServletInitializer{
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

测试

打开浏览器输入http://localhost:8080/demo/save

成功