SpringBoot1.x之数据访问

其他 2020-02-07 10:18:01 阅读次数: 0

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，屏蔽了很多细节设置。引入了各种xxxTemplate，xxxRepository来简化我们对数据访问层的操作。

2 整合基本JDBC和数据源

2.1 JDBC

2.1.1 导入依赖的jar包

<!-- SpringBoot的web模块 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- SpringBoot的web模块 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2.1.2 application.yml配置

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://47.103.20.129:3306/jdbc

2.1.3 测试

  • 示例：
package com.sunxiaping.restful;

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 javax.sql.DataSource;
import java.sql.SQLException;

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

    @Autowired
    private DataSource dataSource;

    @Test
    public void test() throws SQLException {
        System.out.println(dataSource.getClass()); //org.apache.tomcat.jdbc.pool.DataSource
        System.out.println(dataSource.getConnection());
    }

}
  • 效果：
  • 默认是用org.apache.tomcat.jdbc.pool.DataSource作为数据源的。
  • 数据源的相关配置都是在DataSourceProperties里面。
  • 自动配置原理：
  • ①参考DataSourceConfiguration，根据配置创建数据源，默认使用的是Tomcat的连接池，当然可以使用spring.datasource.type指定自定义的数据源类型。其源码如下：
package org.springframework.boot.autoconfigure.jdbc;

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;
        }

    }

}
  • ②SpringBoot默认支持的数据源：
org.apache.tomcat.jdbc.pool.DataSource、HikariDataSource、org.apache.commons.dbcp.BasicDataSource
  • ③自定义数据源类型：
package org.springframework.boot.autoconfigure.jdbc;

abstract class DataSourceConfiguration {

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

        @Bean
        public DataSource dataSource(DataSourceProperties properties) {
            //使用DataSourceProperties创建数据源，利用反射创建相应type类型的数据源，并绑定相关属性
            return properties.initializeDataSourceBuilder().build();
        }
    }

}
  • ④在DataSourceAutoConfiguration注册了DataSourceInitializer这个组件，其源码如下：
package org.springframework.boot.autoconfigure.jdbc;

@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);
    }

 }
  • 而DataSourceInitializer的源码如下：
package org.springframework.boot.autoconfigure.jdbc;

/**
 * Bean to handle {@link DataSource} initialization by running {@literal schema-*.sql} on
 * {@link PostConstruct} and {@literal data-*.sql} SQL scripts on a
 * {@link DataSourceInitializedEvent}.
 *
 * @author Dave Syer
 * @author Phillip Webb
 * @author Eddú Meléndez
 * @author Stephane Nicoll
 * @author Kazuki Shimizu
 * @since 1.1.0
 * @see DataSourceAutoConfiguration
 */
class DataSourceInitializer implements ApplicationListener<DataSourceInitializedEvent> {


}
  • 从中我们可以知道DataSourceInitializer就是ApplicationListener，其作用：
  • 1. runSchemaScripts();运行建表语句。
  • 2. runDataScripts();运行插入数据语句。
schema‐*.sql、data‐*.sql
默认规则：schema.sql，schema‐all.sql；
spring:
  datasource:
    # 建表语句
    schema: 
      - classpath:employee.sql
      - classpath:department.sql 
    # 插入数据语句
    data: 
      - classpath:schema-employee-data.sql
  • ⑤SpringBoot默认自动配置了JdbcTemplate来操作数据库。
package org.springframework.boot.autoconfigure.jdbc;

@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);
    }
}

2.2 整合Druid数据源

2.2.1 导入依赖的jar包

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.21</version>
</dependency>

2.2.2 配置application.yml

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://47.103.20.129:3306/jdbc?characterEncoding=utf-8&useSSL=false
    #指定Druid数据源
    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

2.2.3 DruidConfig.java

  • 示例：
package com.sunxiaping.restful.config;

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.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class DruidConfig {

    @ConfigurationProperties(prefix = "spring.dataSource")
    @Bean
    public DataSource dataSource(){
        return new DruidDataSource();
    }

    //配置Druid的监控
    //1.配置一个管理后台的Servlet
    @Bean
    public ServletRegistrationBean servletRegistrationBean(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(),"/druid/*");

        Map<String,String> map = new HashMap<>();
        map.put("loginUsername", "admin");
        map.put("loginPassword", "123456");
        map.put("allow", "");//默认就是允许所有访问
//        map.put("deny", "192.168.15.21"); 拒绝谁访问

        servletRegistrationBean.setInitParameters(map);

        return servletRegistrationBean;
    }

    //2.配置一个监控的filter
    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

        filterRegistrationBean.setFilter(new WebStatFilter());
        Map<String,String> initParams = new HashMap<>();
        initParams.put("exclusions","*.js,*.css,/druid/*");
        filterRegistrationBean.setInitParameters(initParams);

        filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
        return filterRegistrationBean;
    }



}

3 SpringBoot整合Mybatis

3.1 基础环境搭建

  • pom.xml
<!-- SpringBoot的web模块 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.21</version>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>1.3.1</version>
</dependency>
  • application.yml
spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://47.103.20.129:3306/jdbc?characterEncoding=utf-8&useSSL=false
    #指定Druid数据源
    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
View Code
  • DruidConfig.java
package com.sunxiaping.restful.config;

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.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class DruidConfig {

    @ConfigurationProperties(prefix = "spring.dataSource")
    @Bean
    public DataSource dataSource(){
        return new DruidDataSource();
    }

    //配置Druid的监控
    //1.配置一个管理后台的Servlet
    @Bean
    public ServletRegistrationBean servletRegistrationBean(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(),"/druid/*");

        Map<String,String> map = new HashMap<>();
        map.put("loginUsername", "admin");
        map.put("loginPassword", "123456");
        map.put("allow", "");//默认就是允许所有访问
//        map.put("deny", "192.168.15.21"); 拒绝谁访问

        servletRegistrationBean.setInitParameters(map);

        return servletRegistrationBean;
    }

    //2.配置一个监控的filter
    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

        filterRegistrationBean.setFilter(new WebStatFilter());
        Map<String,String> initParams = new HashMap<>();
        initParams.put("exclusions","*.js,*.css,/druid/*");
        filterRegistrationBean.setInitParameters(initParams);

        filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
        return filterRegistrationBean;
    }



}
View Code
  • 建表语句文件：
/*
Navicat MySQL Data Transfer

Source Server         : 本地
Source Server Version : 50528
Source Host           : 127.0.0.1:3306
Source Database       : restful_crud

Target Server Type    : MYSQL
Target Server Version : 50528
File Encoding         : 65001

Date: 2018-03-05 10:41:40
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for department
-- ----------------------------
DROP TABLE IF EXISTS `department`;
CREATE TABLE `department` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `departmentName` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
View Code 
/*
Navicat MySQL Data Transfer

Source Server         : 本地
Source Server Version : 50528
Source Host           : 127.0.0.1:3306
Source Database       : restful_crud

Target Server Type    : MYSQL
Target Server Version : 50528
File Encoding         : 65001

Date: 2018-03-05 10:41:58
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for employee
-- ----------------------------
DROP TABLE IF EXISTS `employee`;
CREATE TABLE `employee` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `lastName` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `gender` int(2) DEFAULT NULL,
  `d_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
View Code
  • 创建JavaBean：
  • Employee.java
package com.sunxiaping.restful.bean;

public class Employee {

    private Integer id;
    private String lastName;
    private Integer gender;
    private String email;
    private Integer dId;

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

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

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

    public void setEmail(String email) {
        this.email = email;
    }

    public void setdId(Integer dId) {
        this.dId = dId;
    }

    public Integer getId() {
        return id;
    }

    public String getLastName() {
        return lastName;
    }

    public Integer getGender() {
        return gender;
    }

    public String getEmail() {
        return email;
    }

    public Integer getdId() {
        return dId;
    }
}
View Code
  • Department.java
package com.sunxiaping.restful.bean;

public class Department {

    private Integer id;
    private String departmentName;

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

    public void setDepartmentName(String departmentName) {
        this.departmentName = departmentName;
    }

    public Integer getId() {
        return id;
    }

    public String getDepartmentName() {
        return departmentName;
    }
}
View Code

3.2 注解版

  • 示例：
package com.sunxiaping.restful.mapper;

import com.sunxiaping.restful.entities.Department;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Select;

@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 getDeptById(Integer id);

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

}
  • 如果需要自定义Mybatis配置规则，则需要给容器中添加一个ConfigurationCustomizer的组件：
package com.sunxiaping.restful.config;

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

@Configuration
public class MybatisConfig {
    
    public ConfigurationCustomizer configurationCustomizer(){
        return new ConfigurationCustomizer() {
            @Override
            public void customize(org.apache.ibatis.session.Configuration configuration) {
                //开启驼峰命名
                configuration.setMapUnderscoreToCamelCase(true);      
            }
        };
    }
    
}
  • 如果不想在Mapper接口上加@Mapper接口，那么可以在配置类上加上@MapperScan注解即可。
package com.sunxiaping.restful;

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

//使用@MapperScan批量扫描所有的Mapper接口
@MapperScan(value = "com.sunxiaping.restful.mapper")
@SpringBootApplication
public class RestfulApplication {
    public static void main(String[] args) {
        SpringApplication.run(RestfulApplication.class, args);
    }
}

3.3 配置版

  • 在classpath：下新建mybatis-config.xml和EmployeeMapper.xml文件：
  • 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>
View Code
  • 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.restful.mapper.EmployeeMapper">
   <!--    public Employee getEmpById(Integer id);

    public void insertEmp(Employee employee);-->
    <select id="getEmpById" resultType="com.sunxiaping.restful.bean.Employee">
        SELECT * FROM employee WHERE id=#{id}
    </select>


</mapper>
View Code

  • application.yml
mybatis:
  #指定全局配置文件的位置
  config-location: classpath:com/sunxiaping/restful/mybatis-config.xml
  #指定SQL映射问加你的位置
  mapper-locations: classpath:com/sunxiaping/restful/mapper/*.xml

4 SpringBoot整合SpringData JPA

4.1 基础环境搭建

  • pom.xml
<!-- SpringBoot的web模块 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.21</version>
</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>
View Code
  • application.yml
spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    username: root
    password: 123456
    url: jdbc:mysql://47.103.20.129:3306/jdbc?characterEncoding=utf-8&useSSL=false
    #指定Druid数据源
    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
  # jpa
  jpa:
    hibernate:
      # ddl
      ddl-auto: update
    # 显示sql
    show-sql: true
View Code
  • DruidConfig.java
package com.sunxiaping.restful.config;

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.Arrays;
import java.util.HashMap;
import java.util.Map;

@Configuration
public class DruidConfig {

    @ConfigurationProperties(prefix = "spring.dataSource")
    @Bean
    public DataSource dataSource(){
        return new DruidDataSource();
    }

    //配置Druid的监控
    //1.配置一个管理后台的Servlet
    @Bean
    public ServletRegistrationBean servletRegistrationBean(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(),"/druid/*");

        Map<String,String> map = new HashMap<>();
        map.put("loginUsername", "admin");
        map.put("loginPassword", "123456");
        map.put("allow", "");//默认就是允许所有访问
//        map.put("deny", "192.168.15.21"); 拒绝谁访问

        servletRegistrationBean.setInitParameters(map);

        return servletRegistrationBean;
    }

    //2.配置一个监控的filter
    @Bean
    public FilterRegistrationBean filterRegistrationBean(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

        filterRegistrationBean.setFilter(new WebStatFilter());
        Map<String,String> initParams = new HashMap<>();
        initParams.put("exclusions","*.js,*.css,/druid/*");
        filterRegistrationBean.setInitParameters(initParams);

        filterRegistrationBean.setUrlPatterns(Arrays.asList("/*"));
        return filterRegistrationBean;
    }



}
View Code

4.2 编写实体类和映射关系

  • 示例：User.java
package com.sunxiaping.restful.entity;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "`user`")
public class User implements Serializable {

    private Integer id;

    private String lastName;

    private String email;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    public Integer getId() {
        return id;
    }

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

    @Column(name = "`last_name`")
    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Column(name = "`email`")
    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

4.3 编写一个Dao接口来操作实体类对应的数据表

  • 示例：UserRepository.java
package com.sunxiaping.restful.repository;

import com.sunxiaping.restful.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Integer> {

}

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