SpringBoot与数据访问的用法

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1. JDBC

    org.springframework.boot    spring-boot-starter-jdbc    mysql    mysql-connector-java    runtime

spring:  datasource:    username: root    password: zhangjiahui    url: jdbc:mysql://192.168.199.172:3306/jdbc    driver-class-name: com.mysql.cj.jdbc.Driver

效果：

默认是用com.zaxxer.hikari.HikariDataSource作为数据源

数据源相关配置都在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HikariDataSource；可以使用spring.datasource.type指定自定义的数据源类型

2. SpringBoot默认可以支持以下几种数据源

   org.apache.commons.dbcp2.BasicDataSourcecom.zaxxer.hikari.HikariDataSourceorg.apache.tomcat.jdbc.pool.DataSource

   
   

3. 自定义数据源

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

   
   

4. DataSourceInitializerInvoker

DataSourceAutoConfiguration

@Configuration@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })@EnableConfigurationProperties(DataSourceProperties.class)@Import({ DataSourcePoolMetadataProvidersConfiguration.class,      DataSourceInitializationConfiguration.class })public class DataSourceAutoConfiguration {

DataSourceInitializationConfiguration

@Configuration@Import({ DataSourceInitializerInvoker.class,      DataSourceInitializationConfiguration.Registrar.class })class DataSourceInitializationConfiguration {

DataSourceInitializerInvoker

/** * Bean to handle {@link DataSource} initialization by running {@literal schema-*.sql} on * {@link InitializingBean#afterPropertiesSet()} and {@literal data-*.sql} SQL scripts on * a {@link DataSourceSchemaCreatedEvent}. * * @author Stephane Nicoll * @see DataSourceAutoConfiguration */class DataSourceInitializerInvoker      implements ApplicationListener, InitializingBean {        @Override        public void onApplicationEvent(DataSourceSchemaCreatedEvent event) {                // NOTE the event can happen more than once and                // the event datasource is not used here                DataSourceInitializer initializer = getDataSourceInitializer();                if (!this.initialized && initializer != null) {                        initializer.initSchema();                        this.initialized = true;                }        }

4. DataSourceInitializerInvoker将为我们自动创建表并初始化数据，只需要我们将脚本以特定的命名方法，放置在指定的目录即可：

   默认放在classpath路径下，命名规则如下：

1. 建表脚本：schema-*.sql

2. 初始化数据脚本：data-*.sql

自定义路径：

spring:  datasource:    schema:      - classpath:db/department.sql      - classpath:db/init_department.sql

SpringBoot2.X重要设置项：spring.datasource.initialization-mode 初始化模式（springboot2.0），其中有三个值，always为始终执行初始化，embedded只初始化内存数据库（默认值）,如h3等，never为不执行初始化。

注：mysql数据库对大小写敏感

5. JdbcTemplate自动注入

@Configuration@ConditionalOnClass({ DataSource.class, JdbcTemplate.class })@ConditionalOnSingleCandidate(DataSource.class)@AutoConfigureAfter(DataSourceAutoConfiguration.class)@EnableConfigurationProperties(JdbcProperties.class)public class JdbcTemplateAutoConfiguration {

2. 整合基本Druid数据源

Druid数据源配置：

1. 引入数据源

       com.alibaba    druid    1.1.12

   
   

2. 数据源属性绑定

   @Configurationpublic class DruidConfig {    @ConfigurationProperties(prefix = "spring.datasource")    @Bean    public DataSource druid() {        return new DruidDataSource();    }}

   
   

3. 属性配置

   spring:  datasource:    initialSize: 5    minIdle: 5    maxActive: 20    maxWait: 60000    timeBetweenEvictionRunMillis: 60000    minEvictableIdleTimeMillis: 300000    validationQuery: SELECT 1 FROM DUAL    testWhileIdle: true    testOnBorrow: false    testOnReturn: false    poolPreparedStatements: true    #配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙    filters: stat,wall,log4j2    maxPoolPreparedStatementPerConnectionSize: 20    useGlobalDataSourceStat: true    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

   
   

4. 配置Servlet和Filter

@Configurationpublic class DruidConfig {    @Bean    public ServletRegistrationBean statViewServlet() {        ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");        Map initParams = new HashMap<>();        initParams.put("loginUsername", "admin");        initParams.put("loginPassword", "admin");        initParams.put("allow", "");        initParams.put("deny", "");        bean.setInitParameters(initParams);        return bean;    }    @Bean    public FilterRegistrationBean webStatFilter() {        FilterRegistrationBean bean = new FilterRegistrationBean();        Map initParams = new HashMap<>();        initParams.put("exclusions", "*.js,*.png,*.io,/druid/*");        bean.setFilter(new WebStatFilter());        bean.setUrlPatterns(Arrays.asList("/*"));        bean.setInitParameters(initParams);        return bean;    }}

3. 整合Mybatis

    org.mybatis.spring.boot    mybatis-spring-boot-starter    1.3.2

依赖关系：

步骤：

1. 引入依赖、配置属性（见上一节）

2. 建数据库表

3. 创建JavaBean：Department/Employee

4. 实现增删改查

1. 注解版

1. Mapper

//指定这是一个操作数据库的mapper@Mapperpublic 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 dept);    @Update("UPDATE department SET departmentName=${departmentName} WHERE id=${id}")    public int updateDept(Department dept);}

2. Controller

@RestControllerpublic class DeptController {    @Autowired    DepartmentMapper departmentMapper;    @GetMapping("/dept/{id}")    public Department getDept(@PathVariable("id") Integer id) {        return departmentMapper.getDeptById(id);    }    @GetMapping("/dept")    public Department insertDept(Department department) {        departmentMapper.insertDept(department);        return department;    }}

3. 自定义Mybatis配置方法

@org.springframework.context.annotation.Configurationpublic class MybatisConfig {    @Bean    public ConfigurationCustomizer configurationCustomizer() {        return new ConfigurationCustomizer() {            @Override            public void customize(Configuration configuration) {                configuration.setMapUnderscoreToCamelCase(true);            }        };    }}

2. 配置文件版

1. Mapper

//@Mapper或者@MapperScan将接口扫描装配到容器中public interface EmployeeMapper {    public Employee getEmpById(Integer id);    public void insertEmp(Employee employee);}

2. Controller

@Controllerpublic class EmpController {    @Autowired    EmployeeMapper employeeMapper;    @ResponseBody    @GetMapping("/emp/{id}")    public Employee getEmp(@PathVariable(value = "id") Integer id) {        Employee employee = employeeMapper.getEmpById(id);        return employee;    }}

3. mybatis主配置文件mybatis-config.xml

4. mapper配置文件EmployeeMapper.xml

                SELECT * FROM employee WHERE id=#{id}                INSERT INTO employee(last_name, email, gender, department_id, birth) VALUES(#{lastName}, #{email}, #{gender}, #{departmentId}, CURRENT_DATE);    

5. 主配置文件及mapper文件路径指定

#mybatis相关配置，都以mybatis开头mybatis:  #指定主配置文件路径  config-location: classpath:mybatis/mybatis-config.xml  #指定mapper配置文件路径（数组，可使用通配符进行匹配）  mapper-locations: classpath:mybatis/mapper/*.xml

5. 指定Mapper的两种方法

1. 使用@Mapper注解

   //直接将@Mapper注解加在接口类上，指定这是一个操作数据库的mapper@Mapperpublic 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 dept);    @Update("UPDATE department SET departmentName=${departmentName} WHERE id=${id}")    public int updateDept(Department dept);}

   
   

2. 使用@MapperScan(value="mapper-package")注解

   //在SpringBoot主程序上添加注解@MapperScan(value="mapper-package")//则mapper-package包下所有类都会被标识为mapper@MapperScan(value = "com.qiang.springboot.mapper")@SpringBootApplicationpublic class SpringBoot06DataMybatisApplication {    public static void main(String[] args) {        SpringApplication.run(SpringBoot06DataMybatisApplication.class, args);    }}

   
   

4. 整合JPA

1. Spring Data简介

2. 整合Spring Data JPA

JPA是基于ORM（Object Relational Mapping）思想的

1. 编写一个实体类（bean）和数据表进行映射，并且配置好关系

@Entity //告诉JPA这是一个实体类（和数据表映射的类）@Table(name = "tbl_user") //指定和哪个数据表相对应，如果省略此注解，则默认使用小写类名作为映射表名public class User {    /**     * @Id : 告诉JPA这是一个主键字段     * @GeneratedValue : 设置自增     */    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY) //设置自增    private Integer id;    /**     * @Column : 和数据表中某列对应的属性，默认属性名就是列名     */    @Column    private String lastName;    /**     * @Column : 可使用name指定列名，使用length指定列长度     */    @Column(name = "user_email", length = 50)    private String email;        //getter & setter    //...}

2. 编写一个dao接口来操作实体类对应的数据表（Repository）

//Repository必须是一个接口//继承JpaRepository来完成对数据库的操作public interface UserRepository extends JpaRepository {}

3. 基本的配置JpaProperties

spring:  datasource:    url: jdbc:mysql://192.168.199.172:3306/jpa    username: root    password: zhangjiahui    driver-class-name: com.mysql.cj.jdbc.Driver  jpa:    hibernate:      #更新或者创建数据表结构      ddl-auto: update    #在控制台显示SQL    show-sql: true

JPA 2.x版本后 findOne() 的变化

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