java - 在Spring boot中创建外键-H2数据库

Question

假设，我有两个简单的表要在我的 Spring Boot 应用程序中实现。

这是 ER 图:

这是我的PasswordReset 类:

@Data
@Entity
public class PasswordReset {
@Id @GeneratedValue Long passwordResetID;
String eMail;
String token;
String createdAt;


PasswordReset()
{

}
public PasswordReset(String eMail,String token,String createdAt)
{
    this.eMail=eMail;
    this.token=token;
    this.createdAt=createdAt;
}
}

这是我的User类(部分):

@Data
   @Entity
   public class User {
@Id @GeneratedValue Long UserID;
String eMail;
String createdAt;
String updatedAt;


User()
{

}
public User(String eMail,String createdAt,String updatedAt)
{
    this.eMail=eMail;
    this.createdAt=createdAt;
    this.updatedAt=updatedAt;
}
}

现在我的问题是如何在我的 Spring Boot 项目中创建像 ER 图这样的外键？

这是我的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 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>2.1.6.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.mua</groupId>
<artifactId>cse616</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>cse616</name>
<description>Project for CSE-616</description>

<properties>
    <java.version>11</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web-services</artifactId>
    </dependency>

    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </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>

Answer 1

• mappedBy 在父实体(拥有实体)
• CascadeType.PERSIST、CascadeType.ALL 用于在一次请求时保存具有父项的子项(您可以根据需要找到其他项 CascadeType )
• @JoinColumn 位于我们必须加入的列的子实体

User.java

@OneToMany(mappedBy="user",fetch=FetchType.LAZY,cascade = CascadeType.PERSIST)
private List<ResetPassword> resetpassword = new ArrayList<ResetPassword>();

ResetPassword.java

@ManyToOne(fetch = FetchType.LAZY, targetEntity = User.class)
@JoinColumn(name="userId", referencedColumnName = "userId", nullable = false)
private User user;