滕州建网站,东莞浩智建设网站公司,天津工程网站建设,自己做网站都需要什么Spring Boot JpaRepository 示例
Spring Boot建立在 Spring 之上#xff0c;包含 Spring 的所有功能。由于其快速的生产就绪环境#xff0c;使开发人员能够直接专注于逻辑#xff0c;而不必费力配置和设置#xff0c;因此如今它正成为开发人员的最爱。Spring Boot 是一个基…Spring Boot JpaRepository 示例
Spring Boot建立在 Spring 之上包含 Spring 的所有功能。由于其快速的生产就绪环境使开发人员能够直接专注于逻辑而不必费力配置和设置因此如今它正成为开发人员的最爱。Spring Boot 是一个基于微服务的框架在其中创建生产就绪的应用程序只需很少的时间。以下是 Spring Boot 的一些功能
它可以避免 Spring 中繁重的 XML 配置。它提供了 REST 端点的轻松维护和创建。它包括一个嵌入式的 Tomcat 服务器。部署很简单war和jar文件可以轻松地部署在Tomcat服务器中。
有关更多信息请参阅本文Spring Boot 简介。在本文中我们将讨论如何使用JpaRepository来管理 Spring Boot 应用程序中的数据。
Jpa存储库
JpaRepository 是 Repository 的一个JPAJava 持久性 API特定扩展。它包含CrudRepository 和 PagingAndSortingRepository的完整 API 。因此它包含用于基本 CRUD 操作的 API 以及用于分页和排序的 API。
句法
public interface JpaRepositoryT,ID
extends PagingAndSortingRepositoryT,ID, QueryByExampleExecutorT
这里
T存储库管理的域类型通常是实体/模型类名ID存储库管理的实体的 id 类型通常是在实体/模型类中创建的 Id 的包装类
插图
public interface DepartmentRepository extends JpaRepositoryDepartment, Long {}
方法
JpaRepository 中的一些最重要的方法如下
方法 1saveAll()
保存所有给定的实体。
句法
S extends T ListS saveAll(IterableS entities)
参数实体注意它们不能为空也不能包含空。
返回类型已保存的实体永远不会为空。返回的 Iterable 将与作为参数传递的 Iterable 具有相同的大小。
抛出异常如果给定的实体或其某个实体为空则会抛出IllegalArgumentException 。
方法 2getById()
返回具有给定标识符的实体的引用。根据 JPA 持久性提供程序的实现方式这很可能始终返回一个实例并在首次访问时抛出 EntityNotFoundException。其中一些会立即拒绝无效标识符。
句法
T getById(ID id)
参数id – 不能为空。
返回类型对具有给定标识符的实体的引用。
方法 3flush()
刷新数据库中所有待处理的更改。
句法
void flush()
方法 4saveAndFlush()
保存实体并立即刷新更改。
句法
S extends T S saveAndFlush(S entity)
参数要保存的实体。不能为空。
返回类型已保存的实体
方法 5deleteAllInBatch()
批量删除给定实体这意味着它将创建单个查询。此类操作会导致 JPA 一级缓存和数据库不同步。在调用此方法之前请考虑刷新 EntityManager。
句法 void deleteAllInBatch(IterableT entities)
参数要删除的实体不能为空。
实现
让我们考虑一个使用 JpaRepository 管理 Department 实体的 Spring Boot 应用程序。数据保存在 H2 数据库中。我们使用 RESTful 控制器。
步骤1使用IntelliJ IDEA创建Spring Boot项目创建一个Spring Boot项目。
第 2 步添加以下依赖项
Spring WebH2 DatabaseLombokSpring Data JPA
示例这是pom.xml文件的完整代码。
?xml version1.0 encodingUTF-8? project xmlnshttp://maven.apache.org/POM/4.0.0 xmlns:xsihttp://www.w3.org/2001/XMLSchema-instance xsi:schemaLocationhttp://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd !-- Model version -- modelVersion4.0.0/modelVersion !-- Parent configuration for Spring Boot -- parent groupIdorg.springframework.boot/groupId artifactIdspring-boot-starter-parent/artifactId version3.0.0/version relativePath/ !-- lookup parent from repository -- /parent !-- Project metadata -- groupIdcom.amiya/groupId artifactIdSpring-Boot-Demo-Project/artifactId version1.0.0-SNAPSHOT/version nameSpring-Boot-Demo-Project/name descriptionDemo project for Spring Boot/description !-- Java version property -- properties java.version17/java.version /properties !-- Dependencies required for the project -- dependencies !-- Spring Boot Starter Web: To build web applications -- dependency groupIdorg.springframework.boot/groupId artifactIdspring-boot-starter-web/artifactId /dependency !-- Spring Boot Starter Data JPA: To work with JPA for data access -- dependency groupIdorg.springframework.boot/groupId artifactIdspring-boot-starter-data-jpa/artifactId /dependency !-- Spring Boot Starter Validation: For Jakarta EE bean validation -- dependency groupIdorg.springframework.boot/groupId artifactIdspring-boot-starter-validation/artifactId /dependency !-- H2 Database: In-memory database for development and testing -- dependency groupIdcom.h2database/groupId artifactIdh2/artifactId scoperuntime/scope /dependency !-- Lombok: To reduce boilerplate code in Java classes -- dependency groupIdorg.projectlombok/groupId artifactIdlombok/artifactId optionaltrue/optional /dependency /dependencies !-- Build configuration -- build plugins !-- Spring Boot Maven Plugin: To package the application as a jar/war -- plugin groupIdorg.springframework.boot/groupId artifactIdspring-boot-maven-plugin/artifactId configuration excludes !-- Exclude Lombok from the final build -- exclude groupIdorg.projectlombok/groupId artifactIdlombok/artifactId /exclude /excludes /configuration /plugin /plugins /build /project 步骤 3创建下面列出的 4 个包并在这些包中创建一些类和接口如下图所示
entityrepositoryservicecontroller 注意
绿色圆形图标“I”按钮是界面蓝色圆形图标“C”按钮属于类 步骤 4实体包内部
在 Department.java 文件中创建一个简单的POJO 类。
package com.amiya.springbootdemoproject.entity;
import jakarta.persistence.Entity; import jakarta.persistence.GeneratedValue; import jakarta.persistence.GenerationType; import jakarta.persistence.Id; import lombok.AllArgsConstructor; import lombok.Builder; import lombok.Data; import lombok.NoArgsConstructor;
/** * Represents a Department entity in the application. */ Entity Data // Generates getters, setters, toString, equals, and hashCode methods. NoArgsConstructor // Generates a no-args constructor. AllArgsConstructor // Generates a constructor with all arguments. Builder // Generates a builder pattern for creating instances. public class Department { Id // Specifies the primary key of the entity. GeneratedValue(strategy GenerationType.AUTO) // Auto-generates the primary key value. private Long departmentId; // Unique identifier for the department. private String departmentName; // Name of the department. private String departmentAddress; // Address of the department. private String departmentCode; // Code representing the department. } 步骤 5存储库包内部
创建一个简单的接口并将该接口命名为 DepartmentRepository。正如我们上面讨论的那样这个接口将扩展JpaRepository 。 例子
// Java Program to Illustrate DepartmentRepository File
// Importing necessary packages package com.amiya.springbootdemoproject.repository;
import com.amiya.springbootdemoproject.entity.Department; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.stereotype.Repository;
/** * Repository interface for Department entity. * Provides CRUD operations and custom query methods through JpaRepository. */ Repository // Indicates that this interface is a Spring Data repository. public interface DepartmentRepository extends JpaRepositoryDepartment, Long {} 步骤 6服务包内
在包内创建一个名为DepartmentService 的接口和一个名为DepartmentServiceImpl 的类。
示例 1-A
// Java Program to Demonstrate DepartmentService File
// Importing required packages package com.amiya.springbootdemoproject.service;
import com.amiya.springbootdemoproject.entity.Department; import java.util.List;
/** * Service interface for Department entity. * Defines methods for CRUD operations and additional business logic. */ public interface DepartmentService { /** * Saves a department entity. * param department the department to save * return the saved department */ Department saveDepartment(Department department); /** * Fetches the list of all department entities. * return a list of departments */ ListDepartment fetchDepartmentList(); /** * Updates an existing department entity. * param department the department with updated information * param departmentId the ID of the department to update * return the updated department */ Department updateDepartment(Department department, Long departmentId); /** * Deletes a department entity by its ID. * param departmentId the ID of the department to delete */ void deleteDepartmentById(Long departmentId); }
示例 1-B
// Java Program to Illustrate DepartmentServiceImpl File
package com.amiya.springbootdemoproject.service;
import com.amiya.springbootdemoproject.entity.Department; import com.amiya.springbootdemoproject.repository.DepartmentRepository; import java.util.List; import java.util.Objects; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service;
/** * Implementation of DepartmentService. * Provides business logic for handling department-related operations. */ Service // Marks this class as a Spring service component. public class DepartmentServiceImpl implements DepartmentService { Autowired private DepartmentRepository departmentRepository; // Injects the DepartmentRepository dependency. Override public Department saveDepartment(Department department) { // Saves and returns the department entity. return departmentRepository.save(department); } Override public ListDepartment fetchDepartmentList() { // Retrieves and returns a list of all department entities. return (ListDepartment) departmentRepository.findAll(); } Override public Department updateDepartment(Department department, Long departmentId) { // Finds the existing department by ID. Department depDB departmentRepository.findById(departmentId).get(); // Updates fields if they are not null or empty. if (Objects.nonNull(department.getDepartmentName()) !.equalsIgnoreCase(department.getDepartmentName())) { depDB.setDepartmentName(department.getDepartmentName()); } if (Objects.nonNull(department.getDepartmentAddress()) !.equalsIgnoreCase(department.getDepartmentAddress())) { depDB.setDepartmentAddress(department.getDepartmentAddress()); } if (Objects.nonNull(department.getDepartmentCode()) !.equalsIgnoreCase(department.getDepartmentCode())) { depDB.setDepartmentCode(department.getDepartmentCode()); } // Saves and returns the updated department entity. return departmentRepository.save(depDB); } Override public void deleteDepartmentById(Long departmentId) { // Deletes the department entity by its ID. departmentRepository.deleteById(departmentId); } } 步骤 7控制器包装内部
在包内创建一个名为DepartmentController 的类。
// Java Program to Demonstrate DepartmentController File
package com.amiya.springbootdemoproject.controller;
import com.amiya.springbootdemoproject.entity.Department; import com.amiya.springbootdemoproject.service.DepartmentService; import java.util.List; import jakarta.validation.Valid; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*;
/** * REST controller for managing Department entities. * Handles HTTP requests and routes them to the appropriate service methods. */ RestController // Marks this class as a RESTful controller. public class DepartmentController { Autowired private DepartmentService departmentService; // Injects the DepartmentService dependency. /** * Handles POST requests to save a new department. * param department the department entity to be saved * return the saved department entity */ PostMapping(/departments) public Department saveDepartment(Valid RequestBody Department department) { return departmentService.saveDepartment(department); } /** * Handles GET requests to fetch the list of all departments. * return a list of department entities */ GetMapping(/departments) public ListDepartment fetchDepartmentList() { return departmentService.fetchDepartmentList(); } /** * Handles PUT requests to update an existing department. * param department the department entity with updated information * param departmentId the ID of the department to be updated * return the updated department entity */ PutMapping(/departments/{id}) public Department updateDepartment(RequestBody Department department, PathVariable(id) Long departmentId) { return departmentService.updateDepartment(department, departmentId); } /** * Handles DELETE requests to remove a department by ID. * param departmentId the ID of the department to be deleted * return a success message */ DeleteMapping(/departments/{id}) public String deleteDepartmentById(PathVariable(id) Long departmentId) { departmentService.deleteDepartmentById(departmentId); return Deleted Successfully; } } 步骤 8下面是 application.properties 文件的代码
server.port8082# H2 Database
spring.h2.console.enabledtrue
spring.datasource.urljdbc:h2:mem:dcbapp
spring.datasource.driverClassNameorg.h2.Driver
spring.datasource.usernamesa
spring.datasource.passwordpassword
spring.jpa.database-platformorg.hibernate.dialect.H2Dialect
现在运行您的应用程序让我们在 Postman 中测试端点并参考我们的 H2 数据库。
在 Postman 中测试端点
端点 1 POST – http://localhost:8082/departments/ 端点 2 GET – http://localhost:8082/departments/ 端点 3 PUT – http://localhost:8082/departments/1 端点 4删除 – http://localhost:8082/departments/1 H2数据库如下
