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>