Spring Boot Crud 操作示例与 Hibernate · HowToDoInJava 中文系列教程

# Spring Boot Crud 操作示例与 Hibernate > 原文： [https://howtodoinjava.com/spring-boot2/spring-boot-crud-hibernate/](https://howtodoinjava.com/spring-boot2/spring-boot-crud-hibernate/) 学习在 [**spring boot**](https://howtodoinjava.com/spring-boot-tutorials/) 应用程序中为 **CURD 操作**创建 api / 方法，该应用程序使用 [**Hibernate**](https://howtodoinjava.com/hibernate-tutorials/) / jpa 持久性 api 修改数据库中的数据。 ## 1\. 概述在此示例中，我们将创建原始操作并通过 [REST API](http://restfulapi.net/) 公开它们，以便 UI 客户端可以调用这些操作。演示操作使客户端能够修改数据库中的员工记录。该演示的目的是展示使这些交互成为可能的细节，而不涉及现实应用中涉及的业务逻辑的复杂性。 ## 2\. Maven 依赖在此示例中，我们使用 maven 在项目中添加运行时 jar。如果您使用 gradle，请查找相关的依赖项。 `pom.xml` ```java <?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> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.5.RELEASE</version> <relativePath />  </parent> <groupId>com.howtodoinjava.demo</groupId> <artifactId>SpringBoot2Demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>SpringBoot2Demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> ``` * `spring-boot-starter-web`：用于使用 Spring MVC 构建 Web 层，包括 REST API 和应用程序。使用 Tomcat 作为默认的嵌入式容器。 * `spring-boot-starter-data-jpa`：它包括 spring 数据，hibernate，HikariCP，[JPA API](https://howtodoinjava.com/jpa-tutorials-and-examples/) ，**JPA 实现（默认为 Hibernate）**，JDBC 和其他必需的库。 * `h2`：尽管我们可以使用`application.properties`文件中的数据源属性轻松添加任何数据库，但我们仍在使用 h2 数据库来减少不必要的复杂性。 * `spring-boot-starter-test`：用于通过包含 [JUnit](https://howtodoinjava.com/junit-4/)，Hamcrest 和 [Mockito](https://howtodoinjava.com/mockito/junit-mockito-example/) 的库来测试 Spring Boot 应用程序。 ## 3\. Hibernate 配置 #### 3.1. 实体和存储库使用数据库中数据的第一步是在 JPA 实体类中对其结构建模，并为其创建存储库接口。尽可能扩展`JpaRepository`接口，以允许在运行时为任何给定的实体类自动创建存储库实现。实体类别的类型及其 ID 字段在`JpaRepository`的通用参数中指定。请记住，仅包含 JPA API 注解（`javax.persistence.*`）可使 Hibernate 与应用程序代码脱钩。 `EmployeeEntity.java` ```java import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name="TBL_EMPLOYEES") public class EmployeeEntity { @Id @GeneratedValue private Long id; @Column(name="first_name") private String firstName; @Column(name="last_name") private String lastName; @Column(name="email", nullable=false, length=200) private String email; //Setters and getters @Override public String toString() { return "EmployeeEntity [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]"; } } ``` `EmployeeRepository.java` ```java import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.stereotype.Repository; import com.howtodoinjava.demo.entity.EmployeeEntity; @Repository public interface EmployeeRepository extends JpaRepository<EmployeeEntity, Long> { } ``` #### 3.2. 数据源配置要连接到数据库，我们必须配置数据源。我们正在使用 H2 数据库，因此将使用各自的属性。另外，我们使用了几个其他属性来启用 [H2](https://howtodoinjava.com/spring-boot2/h2-database-example/) 控制台和大量日志记录。 `application.properties` ```java spring.datasource.url=jdbc:h2:file:~/test spring.datasource.driverClassName=org.h2.Driver spring.datasource.username=sa spring.datasource.password= spring.jpa.database-platform=org.hibernate.dialect.H2Dialect # Enabling H2 Console spring.h2.console.enabled=true # Custom H2 Console URL spring.h2.console.path=/h2-console # create database schema from SQL files spring.jpa.hibernate.ddl-auto=none #Turn Statistics on and log SQL stmts spring.jpa.show-sql=true spring.jpa.properties.hibernate.format_sql=true spring.jpa.properties.hibernate.generate_statistics=false #logging.level.org.hibernate.type=trace #logging.level.org.hibernate.stat=debug logging.pattern.console=%d{yyyy-MM-dd HH:mm:ss} - %msg%n ``` ## 4\. 服务（使用存储库）服务层是可选的 – 仍然建议执行其他业务逻辑（如果有）。通常，我们将在此处与存储库连接以进行原始操作。 `EmployeeService.java` ```java import java.util.ArrayList; import java.util.List; import java.util.Optional; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.howtodoinjava.demo.entity.EmployeeEntity; import com.howtodoinjava.demo.exception.RecordNotFoundException; import com.howtodoinjava.demo.repository.EmployeeRepository; @Service public class EmployeeService { @Autowired EmployeeRepository repository; public List<EmployeeEntity> getAllEmployees() { List<EmployeeEntity> employeeList = repository.findAll(); if(employeeList.size() > 0) { return employeeList; } else { return new ArrayList<EmployeeEntity>(); } } public EmployeeEntity getEmployeeById(Long id) throws RecordNotFoundException { Optional<EmployeeEntity> employee = repository.findById(id); if(employee.isPresent()) { return employee.get(); } else { throw new RecordNotFoundException("No employee record exist for given id"); } } public EmployeeEntity createOrUpdateEmployee(EmployeeEntity entity) throws RecordNotFoundException { Optional<EmployeeEntity> employee = repository.findById(entity.getId()); if(employee.isPresent()) { EmployeeEntity newEntity = employee.get(); newEntity.setEmail(entity.getEmail()); newEntity.setFirstName(entity.getFirstName()); newEntity.setLastName(entity.getLastName()); newEntity = repository.save(newEntity); return newEntity; } else { entity = repository.save(entity); return entity; } } public void deleteEmployeeById(Long id) throws RecordNotFoundException { Optional<EmployeeEntity> employee = repository.findById(id); if(employee.isPresent()) { repository.deleteById(id); } else { throw new RecordNotFoundException("No employee record exist for given id"); } } } ``` ## 5\. REST 控制器最后，通过 MVC URL 或 REST 端点公开所有操作。客户将与这些端点连接以获取/更新/删除员工记录。请注意注解`@RestController`，`@RequestMapping`，[`@GetMapping`](https://howtodoinjava.com/spring5/webmvc/controller-getmapping-postmapping/)，`@PostMapping`和`@DeleteMapping`，它们将各种 URI 映射到控制器方法。 `EmployeeController.java` ```java import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpStatus; import org.springframework.http.ResponseEntity; import org.springframework.web.bind.annotation.DeleteMapping; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.PostMapping; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; import com.howtodoinjava.demo.entity.EmployeeEntity; import com.howtodoinjava.demo.exception.RecordNotFoundException; import com.howtodoinjava.demo.service.EmployeeService; @RestController @RequestMapping("/employees") public class EmployeeController { @Autowired EmployeeService service; @GetMapping public ResponseEntity<List<EmployeeEntity>> getAllEmployees() { List<EmployeeEntity> list = service.getAllEmployees(); return new ResponseEntity<List<EmployeeEntity>>(list, new HttpHeaders(), HttpStatus.OK); } @GetMapping("/{id}") public ResponseEntity<EmployeeEntity> getEmployeeById(@PathVariable("id") Long id) throws RecordNotFoundException { EmployeeEntity entity = service.getEmployeeById(id); return new ResponseEntity<EmployeeEntity>(entity, new HttpHeaders(), HttpStatus.OK); } @PostMapping public ResponseEntity<EmployeeEntity> createOrUpdateEmployee(EmployeeEntity employee) throws RecordNotFoundException { EmployeeEntity updated = service.createOrUpdateEmployee(employee); return new ResponseEntity<EmployeeEntity>(updated, new HttpHeaders(), HttpStatus.OK); } @DeleteMapping("/{id}") public HttpStatus deleteEmployeeById(@PathVariable("id") Long id) throws RecordNotFoundException { service.deleteEmployeeById(id); return HttpStatus.FORBIDDEN; } } ``` ## 6\. Spring Boot Crud 操作演示现在，完成编码部分后，启动 spring boot 应用程序。它将与 H2 数据库控制台一起使用所有 URL 端点。 * `HTTP GET http://localhost:8080/employees` `Console` ```java Hibernate: select employeeen0_.id as id1_0_, employeeen0_.email as email2_0_, employeeen0_.first_name as first_na3_0_, employeeen0_.last_name as last_nam4_0_ from tbl_employees employeeen0_ ``` `API Response` ```java [ { "id": 1, "firstName": "Lokesh", "lastName": "Gupta", "email": "abc@gmail.com" }, { "id": 2, "firstName": "Deja", "lastName": "Vu", "email": "xyz@email.com" }, { "id": 3, "firstName": "Caption", "lastName": "America", "email": "cap@marvel.com" } ] ``` * `HTTP GET http://localhost:8080/employees/2` `Console` ```java Hibernate: select employeeen0_.id as id1_0_0_, employeeen0_.email as email2_0_0_, employeeen0_.first_name as first_na3_0_0_, employeeen0_.last_name as last_nam4_0_0_ from tbl_employees employeeen0_ where employeeen0_.id=? ``` `API Response` ```java { "id": 2, "firstName": "Deja", "lastName": "Vu", "email": "xyz@email.com" } ``` 在有关**在具有 JPA Hibernate**来管理后端数据更新的 Spring Boot 应用程序中创建和公开 CRUD 操作的注解中，向您提问。学习愉快！ [下载源码](https://howtodoinjava.com/wp-content/downloads/spring-boot-hibernate-crud-demo.zip)