SpringBoot 数据访问

    科技2024-03-13  97

    一、JDBC

    <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> spring: datasource: username: root password: 123456 url: jdbc:mysql://192.168.15.22:3306/jdbc driver-class-name: com.mysql.jdbc.Driver

    效果:

    ​ 默认是用org.apache.tomcat.jdbc.pool.DataSource作为数据源;

    ​ 数据源的相关配置都在DataSourceProperties里面;

    自动配置原理:

    org.springframework.boot.autoconfigure.jdbc:

    1、参考DataSourceConfiguration,根据配置创建数据源,默认使用Tomcat连接池;可以使用spring.datasource.type指定自定义的数据源类型;

    2、SpringBoot默认可以支持;

    org.apache.tomcat.jdbc.pool.DataSource、HikariDataSource、BasicDataSource、

    3、自定义数据源类型

    /** * Generic DataSource configuration. */ @ConditionalOnMissingBean(DataSource.class) @ConditionalOnProperty(name = "spring.datasource.type") static class Generic { @Bean public DataSource dataSource(DataSourceProperties properties) { //使用DataSourceBuilder创建数据源,利用反射创建响应type的数据源,并且绑定相关属性 return properties.initializeDataSourceBuilder().build(); } }

    4、DataSourceInitializer:ApplicationListener;

    ​ 作用:

    ​ 1)、runSchemaScripts();运行建表语句;

    ​ 2)、runDataScripts();运行插入数据的sql语句;

    默认只需要将文件命名为:

    schema-*.sql、data-*.sql 默认规则:schema.sql,schema-all.sql; 可以使用 schema: - classpath:department.sql 指定位置

    5、操作数据库:自动配置了JdbcTemplate操作数据库

    二、整合Druid数据源

    导入druid数据源 @Configuration public class DruidConfig { @ConfigurationProperties(prefix = "spring.datasource") @Bean public DataSource druid(){ return new DruidDataSource(); } //配置Druid的监控 //1、配置一个管理后台的Servlet @Bean public ServletRegistrationBean statViewServlet(){ ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*"); Map<String,String> initParams = new HashMap<>(); initParams.put("loginUsername","admin"); initParams.put("loginPassword","123456"); initParams.put("allow","");//默认就是允许所有访问 initParams.put("deny","192.168.15.21"); bean.setInitParameters(initParams); return bean; } //2、配置一个web监控的filter @Bean public FilterRegistrationBean webStatFilter(){ FilterRegistrationBean bean = new FilterRegistrationBean(); bean.setFilter(new WebStatFilter()); Map<String,String> initParams = new HashMap<>(); initParams.put("exclusions","*.js,*.css,/druid/*"); bean.setInitParameters(initParams); bean.setUrlPatterns(Arrays.asList("/*")); return bean; } }

    三、整合MyBatis

    <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.1</version> </dependency>

    步骤:

    ​ 1)、配置数据源相关属性(见上一节Druid)

    ​ 2)、给数据库建表

    ​ 3)、创建JavaBean

    4)、注解版

    //指定这是一个操作数据库的mapper @Mapper public interface DepartmentMapper { @Select("select * from department where id=#{id}") public Department getDeptById(Integer id); @Delete("delete from department where id=#{id}") public int deleteDeptById(Integer id); @Options(useGeneratedKeys = true,keyProperty = "id") @Insert("insert into department(departmentName) values(#{departmentName})") public int insertDept(Department department); @Update("update department set departmentName=#{departmentName} where id=#{id}") public int updateDept(Department department); }

    问题:

    自定义MyBatis的配置规则;给容器中添加一个ConfigurationCustomizer;

    @org.springframework.context.annotation.Configuration public class MyBatisConfig { @Bean public ConfigurationCustomizer configurationCustomizer(){ return new ConfigurationCustomizer(){ @Override public void customize(Configuration configuration) { configuration.setMapUnderscoreToCamelCase(true); } }; } } 使用MapperScan批量扫描所有的Mapper接口; @MapperScan(value = "com.atguigu.springboot.mapper") @SpringBootApplication public class SpringBoot06DataMybatisApplication { public static void main(String[] args) { SpringApplication.run(SpringBoot06DataMybatisApplication.class, args); } }

    5)、配置文件版

    mybatis: config-location: classpath:mybatis/mybatis-config.xml 指定全局配置文件的位置 mapper-locations: classpath:mybatis/mapper/*.xml 指定sql映射文件的位置

    更多使用参照

    http://www.mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/

    四、整合SpringData JPA

    1)、SpringData简介

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    2)、整合SpringData JPA

    JPA:ORM(Object Relational Mapping);

    1)、编写一个实体类(bean)和数据表进行映射,并且配置好映射关系;

    //使用JPA注解配置映射关系 @Entity //告诉JPA这是一个实体类(和数据表映射的类) @Table(name = "tbl_user") //@Table来指定和哪个数据表对应;如果省略默认表名就是user; public class User { @Id //这是一个主键 @GeneratedValue(strategy = GenerationType.IDENTITY)//自增主键 private Integer id; @Column(name = "last_name",length = 50) //这是和数据表对应的一个列 private String lastName; @Column //省略默认列名就是属性名 private String email;

    2)、编写一个Dao接口来操作实体类对应的数据表(Repository)

    //继承JpaRepository来完成对数据库的操作 public interface UserRepository extends JpaRepository<User,Integer> { }

    3)、基本的配置JpaProperties

    spring: jpa: hibernate: # 更新或者创建数据表结构 ddl-auto: update # 控制台显示SQL show-sql: true
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