基于文件的h2持久但未在Spring Boot中加载 [英] File based h2 persisted but not loaded in Spring Boot

问题描述

我根据Spring Boot制作了一个小应用程序：

I made a small application based on Spring Boot:

• spring-boot-starter-web


• spring-boot-starter-data-jpa

该应用程序只有一个域类 Post。的java 。
因此有一个RestController和一个DAO。
数据应该保存在基于文件的hsql db中。

The application has simply one domain class Post.java. Accordingly there is a RestController and a DAO. The data is supposed to be persisted in a file based hsql db.

当应用程序运行时，一切似乎都很好。数据存储。
h2文件已创建并包含插入语句。

When the application is running everything seems fine. Data is stored. The h2 file is created and contains insert statements.

然而，当我终止应用程序并再次启动它时。没有加载数据。 （好像创建了一个全新的db文件，它覆盖了旧文件）。

However, when I kill the application and start it a second time. No data is loaded. (As if a brand new db file was created, which overwrote the old one).

application.properties

spring.datasource.url = jdbc:h2:file:~/testdb
spring.datasource.username = sa
spring.datasource.password = sa
spring.datasource.driverClassName = org.h2.Driver

pom.xml

<!-- Spring Boot Web -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- Spring Boot Data JPA -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<!-- H2 DB -->
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>1.4.179</version>
</dependency>

PostDAO.java

public interface PostDAO extends JpaRepository<Post, Integer>{
    public Post findByMessage(String message);
}

Post.java

@Entity
public class Post {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;
    private String message;

    public Post(){
    }

    public Post(String message) {
        super();
        this.message = message;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

推荐答案

如果您使用嵌入式数据库， spring.jpa.hibernate.ddl-auto 的默认值为 create-drop 。你可能希望它是空的，或只是验证（无可能也可以，但我认为hibernate不推荐这样做）。

The default for spring.jpa.hibernate.ddl-auto is create-drop if you use an embedded database. You probably want it to be empty, or just validate (none might work as well but I think that's deprecated by hibernate).

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