英文:
Can't generate table from entity Spring Boot
问题
请帮忙！我无法从实体生成表格：
// 类 Application
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
@EntityScan("sb.entity")
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
// 类 Entity
package sb.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name = "category")
public class CategoryEntity {
@Column(name = "name")
private String name;
@Column(name = "code")
private String code;
}
// application.properties
server.port=8081
spring.datasource.url = jdbc:mysql://localhost:3306/springboot_database
spring.datasource.username = root
spring.datasource.password = hoa123456
spring.jpa.hibernate.ddl-auto = create-drop
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
// 文件 pom.xml
<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>
<groupId>sb</groupId>
<artifactId>sb</artifactId>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
</parent>
<properties>
<mysql.version>8.0.13</mysql.version>
<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>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.1.4.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.2.3.Final</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
这是控制台输出： 我在 Stack Overflow 上搜索了，只是已经添加了 <artifactId>spring-boot-starter-data-jpa</artifactId>。
org.springframework.beans.factory.BeanCreationException: 创建名为 'jpaMappingContext' 的 Bean 失败：初始化方法的调用失败；嵌套异常是 java.lang.IllegalArgumentException: 必须至少存在一个 JPA 元模型！
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
...
Caused by: java.lang.IllegalArgumentException: 必须至少存在一个 JPA 元模型！
at org.springframework.util.Assert.notEmpty(Assert.java:277) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.data.jpa.mapping.JpaMetamodelMappingContext.<init>(JpaMetamodelMappingContext.java:52) ~[spring-data-jpa-1.11.9.RELEASE.jar:na]
...
点击此处查看图像描述
1: https://i.stack.imgur.com/XU8mc.png
英文:
Please help !!! I can't generated table from entities**:
// class Application
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
@EntityScan("sb.entity")
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
// class Entity
package sb.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name = "category")
public class CategoryEntity {
@Column(name = "name")
private String name;
@Column(name = "code")
private String code;
}
// application.properties
server.port=8081
spring.datasource.url = jdbc:mysql://localhost:3306/springboot_database
spring.datasource.username = root
spring.datasource.password = hoa123456
spring.jpa.hibernate.ddl-auto = create-drop
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect
// file pom.xml
<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>
<groupId>sb</groupId>
<artifactId>sb</artifactId>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
</parent>
<properties>
<mysql.version>8.0.13</mysql.version>
<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>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.1.4.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>5.2.3.Final</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
This is console: I seach on overstack but i just add <artifactId>spring-boot-starter-data-jpa</artifactId> already.
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: At least one JPA metamodel must be present!
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:742) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
at sb.api.Application.main(Application.java:11) [classes/:na]
Caused by: java.lang.IllegalArgumentException: At least one JPA metamodel must be present!
at org.springframework.util.Assert.notEmpty(Assert.java:277) ~[spring-core-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.data.jpa.mapping.JpaMetamodelMappingContext.<init>(JpaMetamodelMappingContext.java:52) ~[spring-data-jpa-1.11.9.RELEASE.jar:na]
at org.springframework.data.jpa.repository.config.JpaMetamodelMappingContextFactoryBean.createInstance(JpaMetamodelMappingContextFactoryBean.java:71) ~[spring-data-jpa-1.11.9.RELEASE.jar:na]
at org.springframework.data.jpa.repository.config.JpaMetamodelMappingContextFactoryBean.createInstance(JpaMetamodelMappingContextFactoryBean.java:26) ~[spring-data-jpa-1.11.9.RELEASE.jar:na]
at org.springframework.beans.factory.config.AbstractFactoryBean.afterPropertiesSet(AbstractFactoryBean.java:134) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.13.RELEASE.jar:4.3.13.RELEASE]
... 16 common frames omitted
答案1
得分: 1
创建实体时，需要提供@Id注释。这是强制性的。我假设您之前出错是因为没有提供@Id注释。您可以尝试按照以下方式创建实体：
package sb.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Table;
@Entity
@Table(name = "category")
public class CategoryEntity {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@Column(name = "name")
private String name;
@Column(name = "code")
private String code;
}
英文:
When you create an Entity, you need to provide @Id annotation. This is mandatory. I am assuming you are getting error because of the same. Can you try creating entity as
package sb.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name = "category")
public class CategoryEntity {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
Long id;
@Column(name = "name")
private String name;
@Column(name = "code")
private String code;
}
答案2
得分: 0
请确保您已经将Application类的包正确地放置在package下。例如，如果您的Application.java（具有main方法）位于com.sb下面，那么Sb.java实体类应该位于com.sb包下面。
另一个例子
com.sb --> Application.java
com.sb.entity --> CategoryEntity.java
com.notscanned.test --> NotScannedCategoryEntity.java
层次结构很重要，任何位于com.sb.*下的内容都将被Spring自动扫描。
希望这解决了您的问题。
英文:
Please ensure you have that you have the Application class package in correctly placed under package. For example if you have your Application.java( which has main) under com.sb, then Sb.java entity class should be under com.sb package.
Another example
com.sb --> Application.java
com.sb.enity --> CategoryEntity.java
com.notscanned.test --> NotScannedCategoryEntity .java
The hierarchy matters , anything under com.sb.* will be autoscanned by spring.
Hope this solves your problem.
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