JPA全称为Java Persistence API(Java持久层API),它是Sun公司在JavaEE 5中提出的Java持久化规范。
它为Java开发人员提供了一种对象/关联映射工具,来管理Java应用中的关系数据,JPA吸取了目前Java持久化技术的优点,旨在规范、简化Java对象的持久化工作。
JPA对于单表的或者简单的SQL查询非常友好,甚至可以说非常智能。他为你准备好了大量的拿来即用的持久层操作方法。甚至只要写findByName这样一个接口方法,他就能智能的帮你执行根据名称查找实体类对应的表数据,完全不用写SQL。
它相对于mybatis来说不用写xml等配置,简直方便的不行,对于我们开发者来说,谁更简单,开发效率更高,我们就喜欢谁(不喜欢不行,看看产品经理手里的菜刀)!!!
这时候mybatis就不服了,我确实需要写一大堆乱七八糟的xml,但是也可以用注解啊。
还不是要写sql,总是一写增删改查sql,有没有把这些常见的增删改查全部封装起来,我们直接调用api,sql让它们自动组装就好了,说实话我自己封装了一个基于mybatis的组件,常见的增删改查,自己组装成sql去查询,后来由于没有oracle,sqlserver的数据库环境,对这些数据库的时间等等函数支持不好,又有jpa和mybatisplus这些现有的,我也就偷懒了
好了我们之前有实现过springboot-mybatis
springboot-mybatisplus的整合,现在就来实现一下jpa的,你们看看哪个比较方便好用,可以自己用用看
这是我实现的demo预览
由于我想看到效果,又不想装postman来测试,我就集成了swagger
最终效果如上图
好了,我直接放代码了
4.0.0 com.zkb spring-data-jpa 1.0-SNAPSHOT org.apache.maven.plugins maven-compiler-plugin 8 8 org.springframework.boot spring-boot-starter-web 2.1.1.RELEASE org.springframework.boot spring-boot-starter-data-jpa 2.1.1.RELEASE mysql mysql-connector-java 8.0.18 org.projectlombok lombok 1.18.12 org.springframework.boot spring-boot-devtools 2.0.4.RELEASE org.springframework.boot spring-boot-starter-test 2.1.2.RELEASE test com.alibaba druid 1.0.31 org.junit.jupiter junit-jupiter RELEASE compile org.junit.jupiter junit-jupiter RELEASE compile org.slf4j slf4j-api 1.7.25 org.springframework.boot spring-boot-test 2.2.2.RELEASE compile io.springfox springfox-swagger2 2.9.2 io.swagger swagger-annotations io.swagger swagger-models io.swagger swagger-annotations 1.5.22 io.swagger swagger-models 1.5.22 io.springfox springfox-swagger-ui 2.9.2 com.github.xiaoymin swagger-bootstrap-ui 1.9.1
server: port: 5001 spring: datasource: type: com.alibaba.druid.pool.DruidDataSource #Druid 是阿里巴巴开源平台上一个数据库连接池实现,结合了 C3P0、DBCP、PROXOOL 等 DB 池的优点,同时加入了日志监控 driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/test-demo?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC&autoReconnect=true&failOverReadOnly=false&zeroDateTimeBehavior=convertToNull username: root password: root dbcp2: min-idle: 5 initial-size: 5 max-total: 5 max-wait-millis: 200 jpa: database: mysql database-platform: org.hibernate.dialect.MySQL5InnoDBDialect show-sql: true hibernate: ddl-auto: update
package com.zkb.entity; import com.fasterxml.jackson.databind.annotation.JsonSerialize; import com.fasterxml.jackson.databind.ser.std.ToStringSerializer; import io.swagger.annotations.ApiModel; import io.swagger.annotations.ApiModelProperty; import lombok.Data; import javax.persistence.*; /** * 实体类 */ @Entity @Table(name = "t_user") @Data @ApiModel(value = "用户信息", description = "用户信息") public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @ApiModelProperty(value = "主键") @JsonSerialize(using = ToStringSerializer.class) private Long id; @Column(name = "username") @ApiModelProperty(value = "用户名") private String username; @Column(name = "password") @ApiModelProperty(value = "密码") private String password; }
package com.zkb.dao; import com.zkb.entity.User; import org.springframework.data.jpa.repository.JpaRepository; public interface UserRepository extends JpaRepository{ }
package com.zkb.service; import com.zkb.entity.User; import java.util.List; public interface UserService { public void deleteUser(Long id); ListgetList(); }
package com.zkb.service.impl; import com.zkb.dao.UserRepository; import com.zkb.entity.User; import com.zkb.service.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import java.util.List; @Service public class UserServiceImpl implements UserService { @Autowired private UserRepository userRepository; @Override public void deleteUser(Long id) { System.out.println(userRepository); userRepository.deleteById(id); } @Override public ListgetList() { return userRepository.findAll(); } }
package com.zkb.controller; import com.zkb.entity.User; import com.zkb.service.UserService; import io.swagger.annotations.Api; import io.swagger.annotations.ApiOperation; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; import java.util.List; @RestController @RequestMapping("/user") @Api(value = "user",tags = "user") public class UserController { @Autowired private UserService userService; @PostMapping("/del") @ApiOperation(value="删除",notes = "删除") public String delete(@RequestParam("id") Long id){ userService.deleteUser(id); return "true"; } @PostMapping("/getList") @ApiOperation(value="查询所有",notes = "查询所有") public ListgetList(){ return userService.getList(); } }
package com.zkb.conf; import io.swagger.annotations.ApiOperation; import io.swagger.models.auth.In; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import springfox.documentation.builders.ApiInfoBuilder; import springfox.documentation.builders.PathSelectors; import springfox.documentation.builders.RequestHandlerSelectors; import springfox.documentation.service.ApiInfo; import springfox.documentation.service.ApiKey; import springfox.documentation.service.Contact; import springfox.documentation.spi.DocumentationType; import springfox.documentation.spring.web.plugins.Docket; import springfox.documentation.swagger2.annotations.EnableSwagger2; import java.util.Arrays; import java.util.List; @Configuration @EnableSwagger2 public class SwaggerApp { @Bean public Docket createRestApi1() { return new Docket(DocumentationType.SWAGGER_2).enable(true).apiInfo(apiInfo()).select() .apis(RequestHandlerSelectors.withMethodAnnotation(ApiOperation.class)) .apis(RequestHandlerSelectors.basePackage("com.zkb.controller")) .paths(PathSelectors.any()).build().securitySchemes(apiKeyList()).groupName("接口中心"); } private ApiInfo apiInfo() { return new ApiInfoBuilder() .title("API") .contact(new Contact("XXXXX", "http://XXXXXX.XXXX/", "")) .version("1.0") .description("API 描述") .build(); } private ListapiKeyList() { return Arrays.asList(new ApiKey("登录token", "token", In.HEADER.name()), new ApiKey("设备类型(android,ios,pc)---必填", "deviceType", In.HEADER.name())); } }
package com.zkb; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import springfox.documentation.swagger2.annotations.EnableSwagger2; @SpringBootApplication @EnableSwagger2 public class App { public static void main(String[] args) { SpringApplication.run(App.class,args); } }
CREATE TABLE `t_user` ( `id` bigint NOT NULL AUTO_INCREMENT, `username` varchar(50) COLLATE utf8mb4_general_ci DEFAULT NULL, `password` varchar(50) COLLATE utf8mb4_general_ci DEFAULT NULL, PRIMARY KEY (`id`) USING BTREE ) ENGINE=InnoDB AUTO_INCREMENT=1214893367637352451 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;
非常简单的一张表,注意数据库名称
到这里就已经实现了一个非常简单的jpa demo了
当然我这里只是指路,让知怎么用
补充:SpringBoot使用JPA实现增删查改
一、运行环境
SpringBoot2.3.0
JDK1.8
IDEA2020.1.2
MySQL5.7
二、依赖及应用程序配置
org.springframework.boot spring-boot-starter-data-jpa org.springframework.boot spring-boot-starter-thymeleaf org.springframework.boot spring-boot-starter-validation org.springframework.boot spring-boot-starter-web mysql mysql-connector-java runtime org.projectlombok lombok true org.springframework.boot spring-boot-starter-test test org.junit.vintage junit-vintage-engine
1、升级到SpringBoot2.2,spring-boot-starter-test默认使用JUnit 5作为单元测试框架 ,写单元测试时注解@RunWith(Spring.class)升级为@ExtendWith(SpringExtension.class)
2、升级到SpringBoot2.3,hibernate-validator从spring-boot-starter-web移除,需要单独引入
3、升级到SpringBoot2.3,MySQL驱动由com.mysql.jdbc.Driver变更为com.mysql.cj.jdbc.Driver;同时,数据源url需要添加serverTimezone=UTC&useSSL=false参数
3、升级到SpringBoot2.x,默认不自动注入HiddenHttpMethodFilter,需要设置spring.mvc.hiddenmethod.filter.enabled=true开启PUT、DELETE方法支持
应用程序配置如下:
spring.application.name=springbootjpa management.endpoints.jmx.exposure.include=* management.endpoints.web.exposure.include=* management.endpoint.health.show-details=always # 应用服务 WEB 访问端口 server.port=8080 # Actuator Web 访问端口 management.server.port=8081 # mysql setting spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver spring.datasource.url=jdbc:mysql://localhost:3306/springbootjpa?serverTimezone=UTC&useSSL=false spring.datasource.username=username spring.datasource.password=password # JPA setting spring.jpa.properties.hibernate.hbm2ddl.auto=update spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect spring.jpa.show-sql=true # thymeleaf setting spring.thymeleaf.cache=false # delete、put方法支持 spring.mvc.hiddenmethod.filter.enabled=true
三、定义实体
使用@Entity标记实体类
import lombok.Data; import javax.persistence.*; import javax.validation.constraints.NotEmpty; import java.io.Serializable; @Entity @Data public class Article extends BaseEntity implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(nullable = false, unique = true) @NotEmpty(message = "标题不能为空") private String title; @Column(nullable = false) private String body; }
为了自动添加创建日期、修改日期、创建人及修改人,我们把创建、修改信息放到父类中由实体类继承,并开启SpringBoot的自动审计功能,将创建/修改信息自动注入
1、定义实体类的父类,@CreatedDate、@LastModifiedDate、@CreatedBy、@LastModifiedBy标注相应字段
import org.hibernate.annotations.Columns; import org.springframework.data.annotation.CreatedBy; import org.springframework.data.annotation.CreatedDate; import org.springframework.data.annotation.LastModifiedBy; import org.springframework.data.annotation.LastModifiedDate; import org.springframework.data.jpa.domain.support.AuditingEntityListener; import javax.persistence.Column; import javax.persistence.EntityListeners; import javax.persistence.MappedSuperclass; @MappedSuperclass @EntityListeners(AuditingEntityListener.class) public class BaseEntity { @CreatedDate private Long createTime; @LastModifiedDate private Long updateTime; @Column(name = "create_by") @CreatedBy private String createBy; @Column(name = "lastmodified_by") @LastModifiedBy private String lastmodifiedBy; public Long getCreateTime() { return createTime; } public void setCreateTime(Long createTime) { this.createTime = createTime; } public Long getUpdateTime() { return updateTime; } public void setUpdateTime(Long updateTime) { this.updateTime = updateTime; } public String getCreateBy() { return createBy; } public void setCreateBy(String createBy) { this.createBy = createBy; } public String getLastmodifiedBy() { return lastmodifiedBy; } public void setLastmodifiedBy(String lastmodifiedBy) { this.lastmodifiedBy = lastmodifiedBy; } }
@MappedSuperclass注解:
作用于实体类的父类上,父类不生成对应的数据库表
标注@MappedSuperclass的类不能再标注@Entity或@Table注解,也无需实现序列化接口
每个子类(实体类)对应一张数据库表,数据库表包含子类属性和父类属性
标注@MappedSuperclass的类可以直接标注@EntityListeners实体监听器
@EntityListeners(AuditingEntityListener.class)注解:
作用范围仅在标注@MappedSuperclass类的所有继承类中,并且实体监听器可以被其子类继承或重载
开启JPA的审计功能,需要在SpringBoot的入口类标注@EnableJpaAuditing
创建日期、修改日期有默认方法注入值,但创建人和修改人注入则需要手动实现AuditorAware接口:
@Configuration public class BaseEntityAuditor implements AuditorAware{ @Override public Optional getCurrentAuditor() { return ""; } }
四、DAO层实现
JPA支持通过约定方法名进行数据库查询、修改:
import org.springframework.data.jpa.repository.JpaRepository; import springbootjpa.entity.Article; public interface ArticleRepository extends JpaRepository{ Article findById(long id); }
通过约定方法名查询,只需实现JpaRepository接口声明查询方法而不需要具体实现
此外,可以在方法上标注@Query实现JPQL或原生SQL查询
JpaRepository
@Autowired private ArticleRepository articleRepository; @RequestMapping("") public ModelAndView articlelist(@RequestParam(value = "start", defaultValue = "0") Integer start, @RequestParam(value = "limit", defaultValue = "5") Integer limit) { start = start < 0 ? 0 : start; Sort sort = Sort.by(Sort.Direction.DESC, "id"); Pageable pageable = PageRequest.of(start, limit, sort); Pagepage = articleRepository.findAll(pageable); ModelAndView modelAndView = new ModelAndView("article/list"); modelAndView.addObject("page", page); return modelAndView; }
如果根据某一字段排序,可以用Sort.by方法构建Sort对象;如果根据多个字段排序,首先构建Sort.Order数组List
PageRequest.of方法生成Pageable对象
五、Contrller 控制器
import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageRequest; import org.springframework.data.domain.Pageable; import org.springframework.data.domain.Sort; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.*; import org.springframework.web.servlet.ModelAndView; import springbootjpa.entity.Article; import springbootjpa.repository.ArticleRepository; @Controller @RequestMapping("/article") public class ArticleController { @Autowired private ArticleRepository articleRepository; @RequestMapping("") public ModelAndView articlelist(@RequestParam(value = "start", defaultValue = "0") Integer start, @RequestParam(value = "limit", defaultValue = "5") Integer limit) { start = start < 0 ? 0 : start; Sort sort = Sort.by(Sort.Direction.DESC, "id"); Pageable pageable = PageRequest.of(start, limit, sort); Pagepage = articleRepository.findAll(pageable); ModelAndView modelAndView = new ModelAndView("article/list"); modelAndView.addObject("page", page); return modelAndView; } @RequestMapping("/add") public String addArticle() { return "article/add"; } @PostMapping("") public String saveArticle(Article article) { articleRepository.save(article); return "redirect:/article"; } @GetMapping("/{id}") public ModelAndView getArticle(@PathVariable("id") Integer id) { Article article = articleRepository.findById(id); ModelAndView modelAndView = new ModelAndView("article/show"); modelAndView.addObject("article", article); return modelAndView; } @DeleteMapping("/{id}") public String deleteArticle(@PathVariable("id") long id) { System.out.println("put 方法"); articleRepository.deleteById(id); return "redirect:/article"; } @GetMapping("edit/{id}") public ModelAndView editArticle(@PathVariable("id") Integer id) { Article article = articleRepository.findById(id); ModelAndView modelAndView = new ModelAndView("article/edit"); modelAndView.addObject("article", article); return modelAndView; } @PutMapping("/{id}") public String editArticleSave(Article article, long id) { System.out.println("put 方法"); article.setId(id); articleRepository.save(article); return "redirect:/article"; } }
因为