一. 获取数据库连接
1. 之前新建项目时，在Dependencies窗口下，我们只选择了web中的spring-web-starter，现在我们新建一个项目，点击SQL，并勾选以下内容
2. 数据库的连接池这次我们不再使用用阿里家的Druid，而是使用SpringBoot为我们提供的com.zaxxer:HikariCP:3.2.0
ps. 如果想使用Druid，我们还需要在主配置文件中为其配置type：
spring: datasource: type: com.alibaba.druid.pool.DruidDataSource
3. 在SSM框架中，数据源的相关配置都是在applicationContext.xml中导入jdbc.properties进行配置：
<context:property-placeholder location="classpath:jdbc.properties"/>
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}"/> <!-- OGNL-->
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>
而SpringBoot一大特点便是主动为我们提供了很多配置并能简化配置文件，我们点击项目中的External Libraries，找到Maven:org.mybatis.spring.boot:mybatis-spring-boot-autoconfigure:2.1.0，并依次按照下图的中的目录点击找到jdbc中的DataSourceAutoConfiguration
打开DataSourceAutoConfiguration，按住ctrl键，单击DataSourceProperties.class
进入DataSourceProperties.class后，可以看到前缀和相关配置项
接下来我们就可以在application.yml文件中，根据上面的前缀和配置属性对数据库信息进行配置：
spring: datasource: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/gagamall?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC username: root password: zhangjia # type: com.alibaba.druid.pool.DruidDataSource 这里不再采用Druid连接池，而是采用SpringBoot自带的HikariCP
4. 最后编写测试类Springboot06ApplicationTests.java将DataSource注入，即可获取到数据库链接
package io.zhangjia.springboot06;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
@RunWith(SpringRunner.class)
@SpringBootTest
public class Springboot06ApplicationTests {
@Autowired
private DataSource dataSource;
@ Test //@和Test中间并无空格，为避免编辑器bug，所以添加了空格显示
public void contextLoads() throws SQLException {
Connection connection = dataSource.getConnection();
System.out.println(connection);
System.out.println(connection.getClass());
connection.close();
}
}
输出：
HikariProxyConnection@1834755909 wrapping com.mysql.jdbc.JDBC4Connection@44b29496
class com.zaxxer.hikari.pool.HikariProxyConnection
二. SpringBoot整合Mybatis
1. 首先在springboot3中新建mapper包，并编写BookMapper
package io.zhangjia.springboot06.mapper;
import io.zhangjia.springboot06.entity.Book;
import org.springframework.stereotype.Component;
import java.util.List;
@Component
public interface BookMapper {
int doInsert(Book book);
int doDelete(Integer bookId);
int doUpdate(Book book);
List<Book> queryAll();
Book queryById(Integer bookId);
}
2. 接下来在resources中新建mapper包，并添加BookMapper.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="io.zhangjia.springboot06.mapper.BookMapper">
<select id="queryAll" resultType="book">
select *
from book;
</select>
<insert id="doInsert" useGeneratedKeys="true" keyProperty="bookId">
INSERT INTO book (name, author, price) VALUE (#{name}, #{author}, #{price})
</insert>
<delete id="doDelete">
DELETE
FROM book
WHERE BOOK_ID = #{bookId}
</delete>
<update id="doUpdate">
UPDATE book
SET price = #{price},
author =#{author},
name = #{name}
WHERE book_id = #{bookId}
</update>
<select id="queryById" resultType="book">
select *
from book
WHERE book_id = #{bookId};
</select>
</mapper>
3. 编写BookService
package io.zhangjia.springboot06.service;
import io.zhangjia.springboot06.entity.Book;
import java.util.List;
public interface BookService {
List<Book> books();
Book getBook(Integer bookId);
Book saveOrUpdate(Book book);
Book delete(Integer id);
}
4. 实现BookServiceImpl，并添加@Service注解
package io.zhangjia.springboot06.service.impl;
import io.zhangjia.springboot06.entity.Book;
import io.zhangjia.springboot06.mapper.BookMapper;
import io.zhangjia.springboot06.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service("bookService")
public class BookServiceImpl implements BookService {
@Autowired
private BookMapper bookMapper;
@Override
public List<Book> books() {
return bookMapper.queryAll();
}
@Override
public Book getBook(Integer bookId) {
return bookMapper.queryById(bookId);
}
@Override
public Book saveOrUpdate(Book book) {
if (book.getBookId() == null) {
//添加
bookMapper.doInsert(book);
} else {
//修改
bookMapper.doUpdate(book);
}
return book;
}
@Override
public Book delete(Integer id) {
Book book = getBook(id);
bookMapper.doDelete(id);
return book;
}
}
5. 在SSM框架中，关于Mybatis的相关配置是在applicationContext.xml文件中完成的：
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="configLocation" value="classpath:mybatis-config.xml" /> <property name="mapperLocations" value="classpath:mapper/*.xml" /> <property name="typeAliasesPackage" value="io.zhangjia.ssm.entity" /> <!--起别名--> </bean> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer" > <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" /> <property name="basePackage" value="io.zhangjia.ssm.mapper"/> </bean>
SpringBoot也为我们提供了Mybatis的相关配置，点击项目中的External Libraries，找到Maven:org.mybatis.spring.boot:mybatis-spring-boot-autoconfigure:2.1.0，并依次找到jdbc中的autoconfigure中的MybatisAutoConfiguration，点击其中的{MybatisProperties.class}
@EnableConfigurationProperties({MybatisProperties.class})
即可看到Mybatis的配置前缀和相关配置信息：
@ConfigurationProperties(
prefix = "mybatis"
)
public class MybatisProperties {
public static final String MYBATIS_PREFIX = "mybatis";
private static final ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
private String configLocation;
private String[] mapperLocations;
private String typeAliasesPackage;
....
}
接下来在application.yml文件中，添加指定配置即可：
#添加 mybatis: mapper-locations: classpath:mapper/*.xml
注意，关于basePackage的配置，不能在主配置中完成，需要在Springboot启动类Springboot3Application中，添加@MapperScan(“io.zhangjia.springboot3.mapper”)注解。
package io.zhangjia.springboot06;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan(basePackages = "io.zhangjia.springboot06.mapper")
public class SpringBoot06Application {
public static void main(String[] args) {
SpringApplication.run(SpringBoot06Application.class, args);
}
}
6. 编写BookController
package io.zhangjia.springboot06.controller;
import io.zhangjia.springboot06.aspect.LoggingAspect;
import io.zhangjia.springboot06.entity.Book;
import io.zhangjia.springboot06.service.BookService;
import io.zhangjia.springboot06.util.R;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
public class BookController {
@Autowired
private BookService bookService;
private Logger logger = LoggerFactory.getLogger(BookController.class);
@GetMapping(value = "/books", produces = "application/json;charset=utf-8")
public R books() {
List<Book> books = bookService.books();
return R.success(books);
}
@GetMapping(value = "/book/{bookId}", produces = "application/json;charset=utf-8")
public R book(@PathVariable Integer bookId) {
Book book = bookService.getBook(bookId);
logger.info(book.toString());
return R.success(book);
}
@PostMapping(value = "/book", produces = "application/json;charset=utf-8")
public R save(Book book) {
Book book2 = bookService.saveOrUpdate(book);
return R.success(book2);
}
@PutMapping(value = "/book", produces = "application/json;charset=utf-8")
public R update(Book book) {
Book book2 = bookService.saveOrUpdate(book);
return R.success(book2);
}
@DeleteMapping(value = "/book/{bookId}", produces = "application/json;charset=utf-8")
public R delete(@PathVariable Integer bookId) {
Book book = bookService.delete(bookId);
return R.success(book);
}
}
在之前的controller中，我们的方法的返回值都是String类型，如果想把从数据库查到的数据显示在页面中，需要先将查询到的数据转换成JSON字符串，然后再将其返回，但是给Controller添加@RestController注解后，SpringBoot可以直接将查询到的数据直接作为JSON字符串返回，此时访问http://localhost:8888/book，即可查看到查询的数据。关于R类，请查看本站《SpringBoot：使用JSON的工具类进行JSR303数据校验》一文。
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