springboot-jpa的實現(xiàn)操作

更新時間：2021年03月02日 10:01:29 作者：斗碼士

這篇文章主要介紹了springboot-jpa的實現(xiàn)操作，具有很好的參考價值，希望對大家有所幫助。一起跟隨小編過來看看吧

JPA全稱為Java Persistence API（Java持久層API），它是Sun公司在JavaEE 5中提出的Java持久化規(guī)范。

它為Java開發(fā)人員提供了一種對象/關(guān)聯(lián)映射工具，來管理Java應(yīng)用中的關(guān)系數(shù)據(jù)，JPA吸取了目前Java持久化技術(shù)的優(yōu)點，旨在規(guī)范、簡化Java對象的持久化工作。

JPA對于單表的或者簡單的SQL查詢非常友好，甚至可以說非常智能。他為你準(zhǔn)備好了大量的拿來即用的持久層操作方法。甚至只要寫findByName這樣一個接口方法，他就能智能的幫你執(zhí)行根據(jù)名稱查找實體類對應(yīng)的表數(shù)據(jù)，完全不用寫SQL。

它相對于mybatis來說不用寫xml等配置，簡直方便的不行，對于我們開發(fā)者來說，誰更簡單，開發(fā)效率更高，我們就喜歡誰(不喜歡不行，看看產(chǎn)品經(jīng)理手里的菜刀)！??！

這時候mybatis就不服了，我確實需要寫一大堆亂七八糟的xml，但是也可以用注解啊。

還不是要寫sql，總是一寫增刪改查sql，有沒有把這些常見的增刪改查全部封裝起來，我們直接調(diào)用api，sql讓它們自動組裝就好了，說實話我自己封裝了一個基于mybatis的組件，常見的增刪改查，自己組裝成sql去查詢，后來由于沒有oracle，sqlserver的數(shù)據(jù)庫環(huán)境，對這些數(shù)據(jù)庫的時間等等函數(shù)支持不好，又有jpa和mybatisplus這些現(xiàn)有的，我也就偷懶了

好了我們之前有實現(xiàn)過springboot-mybatis

springboot-mybatisplus的整合，現(xiàn)在就來實現(xiàn)一下jpa的，你們看看哪個比較方便好用，可以自己用用看

這是我實現(xiàn)的demo預(yù)覽

由于我想看到效果，又不想裝postman來測試，我就集成了swagger

最終效果如上圖

好了，我直接放代碼了

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
 
  <groupId>com.zkb</groupId>
  <artifactId>spring-data-jpa</artifactId>
  <version>1.0-SNAPSHOT</version>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>8</source>
          <target>8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
      <version>2.1.1.RELEASE</version>
    </dependency>
 
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-jpa</artifactId>
      <version>2.1.1.RELEASE</version>
    </dependency>
 
 
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.18</version>
    </dependency>
 
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.18.12</version>
    </dependency>
 
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-devtools</artifactId>
      <version>2.0.4.RELEASE</version>
    </dependency>
 
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <version>2.1.2.RELEASE</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.alibaba</groupId>
      <artifactId>druid</artifactId>
      <version>1.0.31</version>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>RELEASE</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>RELEASE</version>
      <scope>compile</scope>
    </dependency>
 
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>1.7.25</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-test</artifactId>
      <version>2.2.2.RELEASE</version>
      <scope>compile</scope>
    </dependency>
 
    <dependency>
      <groupId>io.springfox</groupId>
      <artifactId>springfox-swagger2</artifactId>
      <version>2.9.2</version>
      <exclusions>
        <exclusion>
          <groupId>io.swagger</groupId>
          <artifactId>swagger-annotations</artifactId>
        </exclusion>
        <exclusion>
          <groupId>io.swagger</groupId>
          <artifactId>swagger-models</artifactId>
        </exclusion>
      </exclusions>
    </dependency>
    <dependency>
      <groupId>io.swagger</groupId>
      <artifactId>swagger-annotations</artifactId>
      <version>1.5.22</version>
    </dependency>
 
    <dependency>
      <groupId>io.swagger</groupId>
      <artifactId>swagger-models</artifactId>
      <version>1.5.22</version>
    </dependency>
    <!-- swagger-ui -->
    <dependency>
      <groupId>io.springfox</groupId>
      <artifactId>springfox-swagger-ui</artifactId>
      <version>2.9.2</version>
    </dependency>
 
    <dependency>
      <groupId>com.github.xiaoymin</groupId>
      <artifactId>swagger-bootstrap-ui</artifactId>
      <version>1.9.1</version>
    </dependency>
  </dependencies>
 
</project>

server:
 port: 5001
spring:
 datasource:
  type: com.alibaba.druid.pool.DruidDataSource #Druid 是阿里巴巴開源平臺上一個數(shù)據(jù)庫連接池實現(xiàn)，結(jié)合了 C3P0、DBCP、PROXOOL 等 DB 池的優(yōu)點，同時加入了日志監(jiān)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.*; 
/**
 * 實體類
 */
@Entity
@Table(name = "t_user")
@Data
@ApiModel(value = "用戶信息", description = "用戶信息")
public class User { 
  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  @ApiModelProperty(value = "主鍵")
  @JsonSerialize(using = ToStringSerializer.class)
  private Long id;
 
  @Column(name = "username")
  @ApiModelProperty(value = "用戶名")
  private String username;
 
  @Column(name = "password")
  @ApiModelProperty(value = "密碼")
  private String password;
 
}

package com.zkb.dao; 
import com.zkb.entity.User;
import org.springframework.data.jpa.repository.JpaRepository; 
public interface UserRepository extends JpaRepository<User,Long> {
}

package com.zkb.service; 
import com.zkb.entity.User; 
import java.util.List; 
public interface UserService { 
  public void deleteUser(Long id); 
  List<User> getList();
}

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 List<User> getList() {
    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="刪除",notes = "刪除")
  public String delete(@RequestParam("id") Long id){
    userService.deleteUser(id);
    return "true";
  }
 
  @PostMapping("/getList")
  @ApiOperation(value="查詢所有",notes = "查詢所有")
  public List<User> getList(){
    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 List<ApiKey> apiKeyList() {
    return Arrays.asList(new ApiKey("登錄token", "token", In.HEADER.name()),
        new ApiKey("設(shè)備類型(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;

非常簡單的一張表，注意數(shù)據(jù)庫名稱

到這里就已經(jīng)實現(xiàn)了一個非常簡單的jpa demo了

當(dāng)然我這里只是指路，讓知怎么用

補充：SpringBoot使用JPA實現(xiàn)增刪查改

一、運行環(huán)境

SpringBoot2.3.0

JDK1.8

IDEA2020.1.2

MySQL5.7

二、依賴及應(yīng)用程序配置

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</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-validation</artifactId>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <scope>runtime</scope>
</dependency>
<dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <optional>true</optional>
</dependency>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-test</artifactId>
  <scope>test</scope>
  <exclusions>
    <exclusion>
      <groupId>org.junit.vintage</groupId>
      <artifactId>junit-vintage-engine</artifactId>
    </exclusion>
  </exclusions>
</dependency>

1、升級到SpringBoot2.2，spring-boot-starter-test默認(rèn)使用JUnit 5作為單元測試框架，寫單元測試時注解@RunWith(Spring.class)升級為@ExtendWith(SpringExtension.class)

2、升級到SpringBoot2.3，hibernate-validator從spring-boot-starter-web移除，需要單獨引入

3、升級到SpringBoot2.3，MySQL驅(qū)動由com.mysql.jdbc.Driver變更為com.mysql.cj.jdbc.Driver;同時，數(shù)據(jù)源url需要添加serverTimezone=UTC&useSSL=false參數(shù)

3、升級到SpringBoot2.x，默認(rèn)不自動注入HiddenHttpMethodFilter，需要設(shè)置spring.mvc.hiddenmethod.filter.enabled=true開啟PUT、DELETE方法支持

應(yīng)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
# 應(yīng)用服務(wù) WEB 訪問端口
server.port=8080
# Actuator Web 訪問端口
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、定義實體

使用@Entity標(biāo)記實體類

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 = "標(biāo)題不能為空")
  private String title;
  @Column(nullable = false)
  private String body;
}

為了自動添加創(chuàng)建日期、修改日期、創(chuàng)建人及修改人，我們把創(chuàng)建、修改信息放到父類中由實體類繼承，并開啟SpringBoot的自動審計功能，將創(chuàng)建/修改信息自動注入

1、定義實體類的父類,@CreatedDate、@LastModifiedDate、@CreatedBy、@LastModifiedBy標(biāo)注相應(yīng)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：

作用于實體類的父類上，父類不生成對應(yīng)的數(shù)據(jù)庫表

標(biāo)注@MappedSuperclass的類不能再標(biāo)注@Entity或@Table注解，也無需實現(xiàn)序列化接口

每個子類（實體類）對應(yīng)一張數(shù)據(jù)庫表，數(shù)據(jù)庫表包含子類屬性和父類屬性

標(biāo)注@MappedSuperclass的類可以直接標(biāo)注@EntityListeners實體監(jiān)聽器

@EntityListeners(AuditingEntityListener.class)注解：

作用范圍僅在標(biāo)注@MappedSuperclass類的所有繼承類中，并且實體監(jiān)聽器可以被其子類繼承或重載

開啟JPA的審計功能，需要在SpringBoot的入口類標(biāo)注@EnableJpaAuditing

創(chuàng)建日期、修改日期有默認(rèn)方法注入值，但創(chuàng)建人和修改人注入則需要手動實現(xiàn)AuditorAware接口:

@Configuration
public class BaseEntityAuditor implements AuditorAware<String> {
  @Override
  public Optional<String> getCurrentAuditor() {
    return "";
  }
}

四、DAO層實現(xiàn)

JPA支持通過約定方法名進(jìn)行數(shù)據(jù)庫查詢、修改：

import org.springframework.data.jpa.repository.JpaRepository;
import springbootjpa.entity.Article;
public interface ArticleRepository extends JpaRepository<Article, Long> {
  Article findById(long id);
}

通過約定方法名查詢，只需實現(xiàn)JpaRepository接口聲明查詢方法而不需要具體實現(xiàn)

此外，可以在方法上標(biāo)注@Query實現(xiàn)JPQL或原生SQL查詢

JpaRepository<T, ID>,T表示要操作的實體對象，ID表示主鍵。該接口繼承了分頁排序接口PadingAndSortRepository,通過構(gòu)建Pageable實現(xiàn)分頁查詢：

@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);
    Page<Article> page = articleRepository.findAll(pageable);
    ModelAndView modelAndView = new ModelAndView("article/list");
    modelAndView.addObject("page", page);
    return modelAndView;
}

如果根據(jù)某一字段排序，可以用Sort.by方法構(gòu)建Sort對象；如果根據(jù)多個字段排序，首先構(gòu)建Sort.Order數(shù)組List<Sort.Order>,然后再傳入Sort.by方法構(gòu)建Sort對象。

PageRequest.of方法生成Pageable對象

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);
    Page<Article> page = 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";
  }
}

因為<form>表單只能發(fā)送GET或POST請求，spring3引入一個監(jiān)聽器HiddenHttpMethodFilter來將POST請求轉(zhuǎn)換為PUT或POST請求。

SpringBoot2.x開始默認(rèn)不自動注入HiddenHttpMethodFilter，需要設(shè)置spring.mvc.hiddenmethod.filter.enabled=true開啟PUT、DELETE方法支持

配置完后，前端頁面需要在表單中加入隱藏域，表明實際請求方法：

<!-- DELETE 請求 -->
<form id="deletePost" method="POST" action="">
<input type="hidden" name="_method" value="delete">
</form>
<!-- PUT 請求 -->
<form id="putPost" method="POST" action="">
<input type="hidden" name="_method" value="put">
</form>