SpringBoot和数据访问

1 简介

• 对于数据访问层，无论是SQL还是NoSQL，SpringBoot默认采用整合SpringData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。
• 对于我们来说只需要进行简单的设置即可。

2 整合基本JDBC和数据源

2.1 导入相关jar包的maven坐标

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

2.2 配置application.yml

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://192.168.179.100:3306/test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true&nullCatalogMeansCurrent=true
    driver-class-name: com.mysql.jdbc.Driver

• 默认使用的数据源是org.apache.tomcat.jdbc.pool.DataSource。

• 数据源的相关配置都在DataSourceProperties里面。

• 自动配置原理。

• 1️⃣参考org.springframework.boot.autoconfigure.jdbc.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。

abstract class DataSourceConfiguration {
    /**
	 * Tomcat Pool DataSource configuration.
	 */
	@ConditionalOnClass(org.apache.tomcat.jdbc.pool.DataSource.class)
	@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.tomcat.jdbc.pool.DataSource", matchIfMissing = true)
	static class Tomcat extends DataSourceConfiguration {

		@Bean
		@ConfigurationProperties(prefix = "spring.datasource.tomcat")
		public org.apache.tomcat.jdbc.pool.DataSource dataSource(
				DataSourceProperties properties) {
			org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(
					properties, org.apache.tomcat.jdbc.pool.DataSource.class);
			DatabaseDriver databaseDriver = DatabaseDriver
					.fromJdbcUrl(properties.determineUrl());
			String validationQuery = databaseDriver.getValidationQuery();
			if (validationQuery != null) {
				dataSource.setTestOnBorrow(true);
				dataSource.setValidationQuery(validationQuery);
			}
			return dataSource;
		}

	}
    
    	/**
	 * Hikari DataSource configuration.
	 */
	@ConditionalOnClass(HikariDataSource.class)
	@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource", matchIfMissing = true)
	static class Hikari extends DataSourceConfiguration {

		@Bean
		@ConfigurationProperties(prefix = "spring.datasource.hikari")
		public HikariDataSource dataSource(DataSourceProperties properties) {
			return createDataSource(properties, HikariDataSource.class);
		}

	}

	/**
	 * DBCP DataSource configuration.
	 *
	 * @deprecated as of 1.5 in favor of DBCP2
	 */
	@ConditionalOnClass(org.apache.commons.dbcp.BasicDataSource.class)
	@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp.BasicDataSource", matchIfMissing = true)
	@Deprecated
	static class Dbcp extends DataSourceConfiguration {

		@Bean
		@ConfigurationProperties(prefix = "spring.datasource.dbcp")
		public org.apache.commons.dbcp.BasicDataSource dataSource(
				DataSourceProperties properties) {
			org.apache.commons.dbcp.BasicDataSource dataSource = createDataSource(
					properties, org.apache.commons.dbcp.BasicDataSource.class);
			DatabaseDriver databaseDriver = DatabaseDriver
					.fromJdbcUrl(properties.determineUrl());
			String validationQuery = databaseDriver.getValidationQuery();
			if (validationQuery != null) {
				dataSource.setTestOnBorrow(true);
				dataSource.setValidationQuery(validationQuery);
			}
			return dataSource;
		}

	}

	/**
	 * DBCP DataSource configuration.
	 */
	@ConditionalOnClass(org.apache.commons.dbcp2.BasicDataSource.class)
	@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "org.apache.commons.dbcp2.BasicDataSource", matchIfMissing = true)
	static class Dbcp2 extends DataSourceConfiguration {

		@Bean
		@ConfigurationProperties(prefix = "spring.datasource.dbcp2")
		public org.apache.commons.dbcp2.BasicDataSource dataSource(
				DataSourceProperties properties) {
			return createDataSource(properties,
					org.apache.commons.dbcp2.BasicDataSource.class);
		}

	}
    //其他略
    
}    

• 2️⃣SpringBoot默认支持org.apache.tomcat.jdbc.pool.DataSource、HikariDataSource、org.apache.commons.dbcp.BasicDataSource和org.apache.commons.dbcp2.BasicDataSource数据源。
• 3️⃣自定义数据源类型：

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

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

	}
    //其他略
}    

• 4️⃣DataSourceInitializer是ApplicationListener，其作用是：
  • ①运行建表语句，sql脚本的规则是schema-*.sql。
  • ②运行插入数据的语句，sql脚本的规则是data-*.sql。

@Configuration
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@EnableConfigurationProperties(DataSourceProperties.class)
@Import({ Registrar.class, DataSourcePoolMetadataProvidersConfiguration.class })
public class DataSourceAutoConfiguration {
    
 	@Bean
	@ConditionalOnMissingBean
	public DataSourceInitializer dataSourceInitializer(DataSourceProperties properties,
			ApplicationContext applicationContext) {
		return new DataSourceInitializer(properties, applicationContext);
	}   
    //其他略   
}    

• 5️⃣自动配置了JdbcTemplate和NamedParameterJdbcTemplate，用来操作数据库。

package org.springframework.boot.autoconfigure.jdbc;

import javax.sql.DataSource;

import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.core.JdbcOperations;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

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

	private final DataSource dataSource;

	public JdbcTemplateAutoConfiguration(DataSource dataSource) {
		this.dataSource = dataSource;
	}

	@Bean
	@Primary
	@ConditionalOnMissingBean(JdbcOperations.class)
	public JdbcTemplate jdbcTemplate() {
		return new JdbcTemplate(this.dataSource);
	}

	@Bean
	@Primary
	@ConditionalOnMissingBean(NamedParameterJdbcOperations.class)
	public NamedParameterJdbcTemplate namedParameterJdbcTemplate() {
		return new NamedParameterJdbcTemplate(this.dataSource);
	}
}

2.3 整合数据源Druid

2.3.1 引入druid

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.23</version>
</dependency>

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://192.168.64.101:3306/test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true&nullCatalogMeansCurrent=true
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    # 数据源的其他配置
    druid:
      # 初始化
      initial-size: 5
      # 最小
      min-idle: 5
      # 最大
      max-active: 20
      # 连接等待超时时间
      max-wait: 60000
      # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
      time-between-eviction-runs-millis: 60000
      # 配置一个连接在池中最小生存的时间，单位是毫秒
      min-evictable-idle-time-millis: 300000
      validation-query: SELECT 1 FROM DUAL
      test-on-borrow: false
      test-while-idle: true
      test-on-return: false
      # 打开PSCache，并且指定每个连接上PSCache的大小
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      #   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
      #合并多个DruidDataSource的监控数据
      use-global-data-source-stat: true
      # 通过connectProperties属性来打开mergeSql功能；慢SQL记录
      connection-properties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
      # 配置DruidStatFilter
      web-stat-filter:
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*"
      # 配置DruidStatViewServlet
      stat-view-servlet:
        enabled: true
        url-pattern: "/druid/*"
        # IP白名单(没有配置或者为空，则允许所有访问)
#        allow:
        # IP黑名单 (存在共同时，deny优先于allow)
#        deny:
        #  禁用HTML页面上的“Reset All”功能
        reset-enable: false
        # 登录名
        login-username: admin
        # 登录密码
        login-password: 123456

3 整合Mybatis

3.1 导入相关jar包的Maven坐标

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.23</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.3</version>
</dependency>

3.2 sql脚本

DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `gender` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

3.3 创建JavaBean

package com.sunxiaping.springboot.domain;

public class Employee {

    private Integer id;

    private String name;

    private String gender;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                '}';
    }
}

3.4 注解版

• 创建Mapper接口：

package com.sunxiaping.springboot.mapper;

import com.sunxiaping.springboot.domain.Employee;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Options;

//指定这是一个操作数据库的Mapper
@Mapper
public interface EmployeeMapper {

    @Options(useGeneratedKeys = true,keyProperty = "id")
    @Insert("INSERT into `employee` (`name`,`gender`) values (#{name},#{gender})")
    void save(Employee employee);

}

• 在SpringBoot的启动类上加上@MapperScan注解，指定Mapper接口所在的包名

package com.sunxiaping.springboot;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

/**
 * 主程序，用来启动SpringBoot应用
 */
@SpringBootApplication
@ServletComponentScan
//指定扫描的Mapper接口的包名
@MapperScan(basePackages = "com.sunxiaping.springboot.mapper")
public class WebApplication {

    public static void main(String[] args) {
        SpringApplication.run(WebApplication.class, args);
    }

}

• 自定义Mybatis规则：

package com.sunxiaping.springboot.config;


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

@Configuration
public class MybatisConfig {

    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return (configuration)->{
            //开启驼峰命名
            configuration.setMapUnderscoreToCamelCase(true);
        };
    }
}

• 测试：

package com.sunxiaping.springboot;

import com.sunxiaping.springboot.domain.Employee;
import com.sunxiaping.springboot.mapper.EmployeeMapper;
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;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootApplicationTests {

    @Autowired
    private EmployeeMapper employeeMapper;

    @Test
    public void test() {
        Employee employee = new Employee();
        employee.setName("张三");
        employee.setGender("男");

        employeeMapper.save(employee);

        System.out.println("employee = " + employee);
    }
}

3.5 配置版

• 编写EmployeeMapper接口：

package com.sunxiaping.springboot.mapper;

import com.sunxiaping.springboot.domain.Employee;
import org.apache.ibatis.annotations.Mapper;

//指定这是一个操作数据库的Mapper
@Mapper
public interface EmployeeMapper {

    void save( Employee employee);

}

• 编写mybatis-config.xml

<?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>

• 编写EmployeeMapper.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.sunxiaping.springboot.mapper.EmployeeMapper">

    <insert id="save" parameterType="com.sunxiaping.springboot.domain.Employee" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO `employee`(`name`,`gender`)
        VALUES (#{name},#{gender})
    </insert>
</mapper>

• application.yml

spring:
  # 数据源
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://192.168.64.101:3306/test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true&nullCatalogMeansCurrent=true
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    # 数据源的其他配置
    druid:
      # 初始化
      initial-size: 5
      # 最小
      min-idle: 5
      # 最大
      max-active: 20
      # 连接等待超时时间
      max-wait: 60000
      # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
      time-between-eviction-runs-millis: 60000
      # 配置一个连接在池中最小生存的时间，单位是毫秒
      min-evictable-idle-time-millis: 300000
      validation-query: SELECT 1 FROM DUAL
      test-on-borrow: false
      test-while-idle: true
      test-on-return: false
      # 打开PSCache，并且指定每个连接上PSCache的大小
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      #   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
      #合并多个DruidDataSource的监控数据
      use-global-data-source-stat: true
      # 通过connectProperties属性来打开mergeSql功能；慢SQL记录
      connection-properties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
      # 配置DruidStatFilter
      web-stat-filter:
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*"
      # 配置DruidStatViewServlet
      stat-view-servlet:
        enabled: true
        url-pattern: "/druid/*"
        # IP白名单(没有配置或者为空，则允许所有访问)
        #        allow:
        # IP黑名单 (存在共同时，deny优先于allow)
        #        deny:
        #  禁用HTML页面上的“Reset All”功能
        reset-enable: false
        # 登录名
        login-username: admin
        # 登录密码
        login-password: 123456
mybatis:
  mapper-locations: classpath:com/sunxiaping/springboot/mapper/*.xml
  config-location: classpath:mybatis-config.xml

• 测试：

package com.sunxiaping.springboot;

import com.sunxiaping.springboot.domain.Employee;
import com.sunxiaping.springboot.mapper.EmployeeMapper;
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;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootApplicationTests {

    @Autowired
    private EmployeeMapper employeeMapper;

    @Test
    public void test() {
        Employee employee = new Employee();
        employee.setName("张三");
        employee.setGender("男");

        employeeMapper.save(employee);

        System.out.println("employee = " + employee);
    }
}

4 整合JPA

4.1 导入相关jar包的Maven坐标：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.23</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

4.2 编写实体类

package com.sunxiaping.springboot.domain;

import javax.persistence.*;

@Entity
@Table(name = "`employee`")
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "`name`")
    private String name;

    @Column(name = "`gender`")
    private String gender;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                '}';
    }
}

4.3 编写application.yml

spring:
  # 数据源
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://192.168.64.101:3306/test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&serverTimezone=GMT%2B8&allowPublicKeyRetrieval=true&nullCatalogMeansCurrent=true
    driver-class-name: com.mysql.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    # 数据源的其他配置
    druid:
      # 初始化
      initial-size: 5
      # 最小
      min-idle: 5
      # 最大
      max-active: 20
      # 连接等待超时时间
      max-wait: 60000
      # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
      time-between-eviction-runs-millis: 60000
      # 配置一个连接在池中最小生存的时间，单位是毫秒
      min-evictable-idle-time-millis: 300000
      validation-query: SELECT 1 FROM DUAL
      test-on-borrow: false
      test-while-idle: true
      test-on-return: false
      # 打开PSCache，并且指定每个连接上PSCache的大小
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      #   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
      #合并多个DruidDataSource的监控数据
      use-global-data-source-stat: true
      # 通过connectProperties属性来打开mergeSql功能；慢SQL记录
      connection-properties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
      # 配置DruidStatFilter
      web-stat-filter:
        enabled: true
        url-pattern: "/*"
        exclusions: "*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*"
      # 配置DruidStatViewServlet
      stat-view-servlet:
        enabled: true
        url-pattern: "/druid/*"
        # IP白名单(没有配置或者为空，则允许所有访问)
        #        allow:
        # IP黑名单 (存在共同时，deny优先于allow)
        #        deny:
        #  禁用HTML页面上的“Reset All”功能
        reset-enable: false
        # 登录名
        login-username: admin
        # 登录密码
        login-password: 123456
  jpa:
    show-sql: true
    open-in-view: true
    hibernate:
      ddl-auto: update

4.3 编写Repository

package com.sunxiaping.springboot.repository;

import com.sunxiaping.springboot.domain.Employee;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

public interface EmployeeRepository extends JpaRepository<Employee,Integer>, JpaSpecificationExecutor<Employee> {

}

4.4 测试

package com.sunxiaping.springboot;

import com.sunxiaping.springboot.domain.Employee;
import com.sunxiaping.springboot.repository.EmployeeRepository;
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 java.util.List;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootApplicationTests {

    @Autowired
    private EmployeeRepository employeeRepository;


    @Test
    public void test() {
        System.out.println("employeeRepository = " + employeeRepository);

        List<Employee> employeeList = employeeRepository.findAll();

        System.out.println("employeeList = " + employeeList);

    }
}