SpringBoot(九) -- SpringBoot与数据访问

一.简介
　　对于数据访问层，无论是SQL还是NOSQL，Spring Boot默认采用整合Spring Data的方式进行统一处理，添加大量自动配置，屏蔽了很多设置。引入各种xxxTemplate，xxxRepository来简化我们对数据访问层的操作。对我们来说只需要进行简单的设置即可。

二.整合JDBC和数据源
　　1.查看POM依赖:

　　2.配置datasource:

　　3.观察其自动装配:

　　4.在其运行时,具有一个DataSourceConfiguration的类,可以实现自定义的数据源配置,默认启用tomcat.jdbc数据源,同时还支持HikariDataSource,dbcp,dbcp2等数据源,我们还可以自定义数据源:

     /**
      * Generic DataSource configuration.
      */
     @ConditionalOnMissingBean(DataSource.class)
     @ConditionalOnProperty(name = "spring.datasource.type")
     static class Generic {

         @Bean
         public DataSource dataSource(DataSourceProperties properties) {
             return properties.initializeDataSourceBuilder().build();
         }

     } 

　　4.自定义的数据源使用DataSourceBulider来实现自定义数据源的装配,使用反射去创建我们自定义的数据源:

     public DataSource build() {
         Class<? extends DataSource> type = getType();
         DataSource result = BeanUtils.instantiate(type);
         maybeGetDriverClassName();
         bind(result);
         return result;
     }

　　5.在DataSourceInitializer类中定义了一个 DataSourceInitializer implements ApplicationListener<DataSourceInitializedEvent>,该类主要可以帮助我们在程序初始化的时候自动云运行 schema-*.sql data-*.sql:

     @PostConstruct
     public void init() {
         if (!this.properties.isInitialize()) {
             logger.debug("Initialization disabled (not running DDL scripts)");
             return;
         }
         if (this.applicationContext.getBeanNamesForType(DataSource.class, false,
                 false).length > 0) {
             this.dataSource = this.applicationContext.getBean(DataSource.class);
         }
         if (this.dataSource == null) {
             logger.debug("No DataSource found so not initializing");
             return;
         }
         runSchemaScripts();
     }

　　6.可以在程序运行时帮助我们执行建表语句;
　　7.运行插入数据的sql语句:

     @Override
     public void onApplicationEvent(DataSourceInitializedEvent event) {
         if (!this.properties.isInitialize()) {
             logger.debug("Initialization disabled (not running data scripts)");
             return;
         }
         // NOTE the event can happen more than once and
         // the event datasource is not used here
         if (!this.initialized) {
             runDataScripts();
             this.initialized = true;
         }
     }

　　8.其默认规则只需要将这些文件命名为scheme-*.sql(建表语句),data-*.sql(数据形式的sql文件);将建表语句的sql文件放置在resources文件夹下命名为schema-all(schema).sql,则将在程序运行时自动创建我们的建表语句:

　　9.我们也可以在配置属性文件中直接指定schema:

　　10.如果我们要操作数据库,SpringBoot还具有一个默认的自动配置:JdbcTemplateAutoConfiguration:自动配置了JdbcTemplate操纵数据库

三.数据库操纵演示
　　自定义一个Controller实现数据查询:

 package com.skykuqi.springboot.datajdbc.controller;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.ResponseBody;

 import java.util.List;
 import java.util.Map;

 /**
  * @author : S K Y
  * @version :0.0.1
  */
 @Controller
 public class HelloController {

     @Autowired
     JdbcTemplate template;

     @ResponseBody
     @GetMapping("/query")
     public Map<String, Object> map() {
         List<Map<String, Object>> list = template.queryForList("select * from department");
         return list.get(0);
     }
 }

四.整合使用druid数据源
　　1.引入druid:

         <!--引入druid数据源-->
         <dependency>
             <groupId>com.alibaba</groupId>
             <artifactId>druid</artifactId>
             <version>1.1.8</version>
         </dependency>

　　2.配置druid数据源

 package com.skykuqi.springboot.datajdbc.condig;

 import com.alibaba.druid.pool.DruidDataSource;
 import com.alibaba.druid.support.http.StatViewServlet;
 import com.alibaba.druid.support.http.WebStatFilter;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.boot.web.servlet.ServletRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 import javax.sql.DataSource;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;

 /**
  * @author : S K Y
  * @version :0.0.1
  */
 @Configuration
 public class DruidConfig {
     @Bean
     @ConfigurationProperties(prefix = "spring.datasource")
     public DataSource druid() {
         return new DruidDataSource();
     }

     //配置Durid的监控
     //1. 配置一个管理后台的Service
     @Bean
     public ServletRegistrationBean statViewServlet() {
         ServletRegistrationBean bean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
         Map<String, String> initParameters = new HashMap<>();
         //配置登录后台时的用户名
         initParameters.put("loginUsername", "admin");
         //配置登录后台的密码
         initParameters.put("loginPassword", "123456");
         //默认允许所有访问,配置只允许本地登录
         initParameters.put("allow", "127.0.0.1");
         //阻止该地址的访问
         initParameters.put("deny", "192.168.1.108");
         bean.setInitParameters(initParameters);
         return bean;
     }

     //2.配置一个监控的filter
     @Bean
     public FilterRegistrationBean webStartFilter() {
         FilterRegistrationBean bean = new FilterRegistrationBean();
         bean.setFilter(new WebStatFilter());
         Map<String, String> initParameters = new HashMap<>();
         //设置不拦截以下请求
         initParameters.put("exclusions","*.js,*.css,/druid");
         //设置拦截以下所有请求
         bean.setInitParameters(initParameters);
         bean.setUrlPatterns(Collections.singletonList("/*"));
         return bean;
     }
 }

 spring:
   datasource:
     username: root
     password: 123456
     url: jdbc:mysql://192.168.1.108:3306/jdbc?useSSL=false
     driver-class-name: com.mysql.jdbc.Driver
     schema:
       - classpath:department.sql
     type: com.alibaba.druid.pool.DruidDataSource
     #   数据源其他配置
     initialSize: 5
     minIdle: 5
     maxActive: 20
     maxWait: 60000
     timeBetweenEvictionRunsMillis: 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,log4j
     maxPoolPreparedStatementPerConnectionSize: 20
     useGlobalDataSourceStat: true
     connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

五.整合Mybatis
　　1.查看POM依赖

     <dependencies>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-jdbc</artifactId>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
         </dependency>
         <dependency>
             <groupId>org.mybatis.spring.boot</groupId>
             <artifactId>mybatis-spring-boot-starter</artifactId>
             <version>2.1.1</version>
         </dependency>

         <dependency>
             <groupId>mysql</groupId>
             <artifactId>mysql-connector-java</artifactId>
             <scope>runtime</scope>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
     </dependencies>

　　2.配置使用Mybatis
　　(1)配置数据源相关;
　　(2)在数据库中建立相关数据表
　　(3)创建javaBean;
　　(4)使用SpringBoot整合Mybatis;

 package com.skykuqi.springboot.mybatis.mapper;

 import com.skykuqi.springboot.mybatis.entity.Department;
 import org.apache.ibatis.annotations.*;

 /**
  * @author : S K Y
  * @version :0.0.1
  */
 @Mapper     //指定这是一个操作数据库的mapper
 public interface DepartmentMapper {
     @Select("select * from department where id=#{id}")
     Department queryDepartmentById(Integer id);

     @Delete("delete from department where id=#{id}")
     int deleteDepartmentById(Integer id);

     @Insert("insert into department(departmentName) values(#{departmentName}) ")
     int insertDepartment(Department department);

     @Update("update department set departmentName=#{departmentName} where id=#{id}")
     int updataDepartment(Department department);
 }

 package com.skykuqi.springboot.mybatis.controller;

 import com.skykuqi.springboot.mybatis.entity.Department;
 import com.skykuqi.springboot.mybatis.mapper.DepartmentMapper;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;

 /**
  * @author : S K Y
  * @version :0.0.1
  */
 @org.springframework.web.bind.annotation.RestController
 public class RestController {
     @Autowired
     DepartmentMapper departmentMapper;

     @GetMapping("/dept/{id}")
     public Department getDepartment(@PathVariable("id") Integer id) {
         return departmentMapper.queryDepartmentById(id);
     }

     @GetMapping("/dept")
     public Department insertDept(Department department) {
         departmentMapper.insertDepartment(department);
         return department;
     }
 }

　　--实现插入语句的id值回显:

     @Options(useGeneratedKeys = true,keyProperty = "id")
     @Insert("insert into department(departmentName) values(#{departmentName}) ")
     int insertDepartment(Department department);

　　(5)当javaBean中的名称与数据库中的名称不一致时.例如javaBean中为departmentName,而在数据库中为department_name,在Mybatis的自动配置中存在ConfigurationCustomizer相关的配置,我们可以自定义实现该接口:

 package com.skykuqi.springboot.mybatis.config;

 import org.mybatis.spring.boot.autoconfigure.ConfigurationCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;

 /**
  * @author : S K Y
  * @version :0.0.1
  */
 @Configuration
 public class MyBatisConfig {
     @Bean
     public ConfigurationCustomizer configurationCustomizer() {
         return configuration -> {
             configuration.setMapUnderscoreToCamelCase(true);        //开启驼峰命名法
         };
     }
 }

　　(6)可以使用@MapperScan 来配置mapper包扫描,避免过多的Mapper注解的实现

　　3.使用配置文件的方式来进行Mybatis的整合
　　(1)在yml配置文件中注册配置类:

　　(2)在xml文件中配置启用mapUnderscoreToCamelCase

 <?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>
     <settings>
         <setting name="mapUnderscoreToCamelCase" value="true"/>
     </settings>
 </configuration>

　　(3)编写mapper.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.skykuqi.springboot.mybatis.mapper.EmployeeMapper">
     <select id="queryEmpById" parameterType="Integer"
             resultType="com.skykuqi.springboot.mybatis.entity.Employee">
         select *
         from employee
         where id = #{id}
     </select>

     <insert id="insertEmp" parameterType="com.skykuqi.springboot.mybatis.entity.Employee">
         insert into employee(lastName, email, gender, d_id)
         values (#{lastName}, #{email}, #{gender}, #{d_id})
     </insert>
 </mapper>