我對 maven spring boot 還很陌生。
我正在運行，mvn clean install然后mvn spring-boot:run
我可以發布 http 帖子并將資料插入資料庫。我可以做一個 http 獲取并查看資料。我可以在mysql中查看資料。
當我重新編譯并mvn clean install再次運行時，我不確定是什么導致它洗掉了資料庫中我的產品表中的所有資料。
pom.xml
<?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 https://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>2.7.0</version>
<relativePath/>
<!-- lookup parent from repository -->
</parent>
<groupId>sample.info</groupId>
<artifactId>mainapp</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>mainapp</name>
<description>Spring Boot Project</description>
<properties>
<java.version>18</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.session</groupId>
<artifactId>spring-session-core</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<configuration>
<forkCount>0</forkCount>
<reuseForks>true</reuseForks>
<argLine>-Xmx1024m -XX:MaxPermSize=256m</argLine>
</configuration>
</plugin>
</plugins>
</build>
</project>
應用程式屬性
spring.jpa.hibernate.ddl-auto=create
spring.datasource.url=jdbc:mysql://localhost:3306/appdb
spring.datasource.username=root
spring.datasource.password=
server.port = 9095
MainappApplication.java
package sample.info.mainapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
@EnableJpaAuditing
@SpringBootApplication
public class MainappApplication {
public static void main(String[] args) {
SpringApplication.run(MainappApplication.class, args);
}
}
控制器/ProductController.java
package sample.info.mainapp.controllers;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
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.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import sample.info.mainapp.model.Product;
import sample.info.mainapp.repository.ProductRepository;
@RestController
@RequestMapping("/api")
public class ProductController {
@Autowired
ProductRepository productRepository;
@GetMapping("/products")
public List<Product> getAllProducts() {
final List<Product> productList = new ArrayList<Product>();
Iterable<Product> iterable = productRepository.findAll();
iterable.forEach(productList::add);
return productList;
}
@GetMapping("/products/{id}")
public ResponseEntity<Product> getProductById(@PathVariable(value = "id") Long id) {
Optional<Product> product = productRepository.findById(id);
return product.isPresent() ? new ResponseEntity<Product>(product.get(), HttpStatus.OK)
: new ResponseEntity("No data found", HttpStatus.NOT_FOUND);
}
@PostMapping("/products")
public Product createProduct(@RequestBody Product product) {
return productRepository.save(product);
}
@PutMapping("/products/{id}")
public ResponseEntity<Product> updateProduct(@PathVariable(value = "id") Long id, @RequestBody Product newProduct) {
Optional<Product> product = productRepository.findById(id);
if (product.isPresent()) {
Product prod = product.get();
prod.setDescription(newProduct.getDescription());
prod.setPrice(newProduct.getPrice());
prod.setTitle(newProduct.getTitle());
prod = productRepository.save(prod);
return ResponseEntity.ok().body(prod);
} else {
return ResponseEntity.notFound().build();
}
}
@DeleteMapping("/products/{id}")
public ResponseEntity<Product> deleteProduct(@PathVariable(value = "id") Long id) {
Optional<Product> product = productRepository.findById(id);
if (product.isPresent()) {
productRepository.delete(product.get());
return new ResponseEntity("Product has been deleted successfully.", HttpStatus.OK);
} else {
return ResponseEntity.notFound().build();
}
}
}
模型/Product.java
package sample.info.mainapp.model;
import javax.persistence.*;
import org.springframework.data.annotation.CreatedDate;
import org.springframework.data.annotation.LastModifiedDate;
import org.springframework.data.jpa.domain.support.AuditingEntityListener;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import java.util.Date;
@Entity
@Table(name = "products")
@EntityListeners(AuditingEntityListener.class)
@JsonIgnoreProperties(value = { "created_at", "updated_at" }, allowGetters = true)
public class Product {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@Column(name = "title")
private String title;
@Column(name = "description")
private String description;
@Column(name = "price")
private float price;
@Column(nullable = false, updatable = false)
@Temporal(TemporalType.TIMESTAMP)
@CreatedDate
private Date created_at;
@Column(nullable = false)
@Temporal(TemporalType.TIMESTAMP)
@LastModifiedDate
private Date updated_at;
public Product() {
}
public Product(Long id, String title, String description, float price) {
this.id = id;
this.title = title;
this.description = description;
this.price = price;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
public Date getCreated_at() {
return created_at;
}
public Date getUpdated_at() {
return updated_at;
}
}
存盤庫/ProductRepository.java
package sample.info.mainapp.repository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import sample.info.mainapp.model.Product;
@Repository
public interface ProductRepository extends CrudRepository <Product, Long> {
}
uj5u.com熱心網友回復：
spring.jpa.hibernate.ddl-auto = create-- Hibernate 首先洗掉現有表，然后創建新表。點擊這里了解更多詳情。
從中洗掉/評論此屬性application.properties并嘗試。
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