如何在 Spring Boot 中跳过某些 @Entity 类在 h2（内存中）数据库中创建为表？答案

【问题标题】：How do I skip certain @Entity classes from being created as a table in h2 (in memory) database in Spring Boot?如何在 Spring Boot 中跳过某些 @Entity 类在 h2（内存中）数据库中创建为表？
【发布时间】：2020-06-10 17:14:34
【问题描述】：

我正在尝试构建一个使用 2 个数据源的 Spring Boot 应用程序。我现在的主数据库是内存数据库（仅用于测试目的），其中的表是在我创建的 sql 文件的帮助下填充的。另一个数据库 (oracledb) 具有已填充的表。

我想达到什么目的？ 我正在尝试从 oracledb 中提取数据，对其进行处理并在 h2 数据库中填充表。

我面临什么问题？ 我只希望将 h2 db 的实体创建为 in-mem 数据库中的表（我希望能够指定 h2 扫描和创建表的实体，而不是所有具有 @Entity 注释的类）。所有具有@Entity 的类都在我的内存数据库中创建为表，这就是我要避免的。

我尝试了什么？ 我为属于 h2 和 oracledb 的实体创建了两个单独的包，并使用 @EntityScan 我只扫描了包含 h2 实体的包。这行得通，但是，我需要扫描 oracledb 的其他实体，以便我能够使用它们。

我所拥有的代码片段：

我的 applications.properties 文件

#spring.jpa.hibernate.ddl-auto=none
spring.jpa.generate-ddl=true

spring.h2.console.enabled=true
spring.h2.console.path=/h2


# first data source
spring.datasource.url=jdbc:h2:mem:mydb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=

spring.application.name=Health Monitor


## 2nd data source
spring.production-datasource.url= jdbc:oracle://localhost:3306/db2
spring.production-datasource.driverClassName=oracle.jdbc.driver.OracleDriver
spring.production-datasource.username=abcd
spring.production-datasource.password=xyz123

DemoApplication.java

package com.automation.demo;

import java.sql.SQLException;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.domain.EntityScan;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
//@EntityScan( basePackages = {"domain"} )
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }


    @Bean(initMethod = "start", destroyMethod = "stop")
    public org.h2.tools.Server inMemoryH2DatabaseaServer() throws SQLException {
        return org.h2.tools.Server.createTcpServer(
          "-tcp", "-tcpAllowOthers", "-tcpPort", "9090");
    }



}

ConfigureDB.java

package com.automation.demo.configurations;

import javax.sql.DataSource;

import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

import com.zaxxer.hikari.HikariDataSource;

@Configuration
public class ConfigureDB {

    @Primary
    @Bean
    @ConfigurationProperties(prefix="spring.datasource")
    public DataSourceProperties devDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("spring.datasource.configuration")
    public DataSource devDataSource() {
        return devDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();
    }

    @Bean
    @ConfigurationProperties("spring.production-datasource")
    public DataSourceProperties productionDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @ConfigurationProperties("spring.production-datasource.configuration")
    public DataSource productionDataSource() {

        return productionDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();

    }

}

Employee.java（用于 h2 数据库）

package com.automation.demo.dev.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="test")
public class Employee {

    // define fields
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="ID")
    private int id;

    @Column(name="FirstName")
    private String firstName;

    @Column(name="LastName")
    private String lastName;

    @Column(name="Email")
    private String email;


    // define constructors

    public Employee() {

    }

    public Employee(String firstName, String lastName, String email) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

    // define getter/setter

    public int getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    // define tostring

    @Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
    }

}

CustomerInfo.java（这是oracledb中代表表的实体，我想防止在h2数据库中创建代表该实体的表）

package com.automation.demo.production.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="customer")
public class CustomerInfo {

    // define fields
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="ID")
    private int id;

    @Column(name="FirstName")
    private String firstName;

    @Column(name="LastName")
    private String lastName;

    @Column(name="Email")
    private String email;


    // define constructors

    public CustomerInfo() {

    }

    public CustomerInfo(String firstName, String lastName, String email) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
    }

    // define getter/setter

    public int getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    // define tostring

    @Override
    public String toString() {
        return "Customer [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
    }

}

如果我遗漏了什么，请告诉我。此外，如果我犯了任何其他错误但与我当前的问题无关，请同时提及。

谢谢。

【问题讨论】：

您还需要在 SpringBoot 中配置 2 个 EntityManagers ... 每个数据源一个。

标签： java spring hibernate spring-boot jpa

【解决方案1】：

Hibernate 可以通过 SchemaFilterProvider 完成此操作。

SchemaFilterProvider

public class MySchemaFilterProvider implements SchemaFilterProvider {

    @Override
    public SchemaFilter getCreateFilter() {
        return MySchemaFilter.INSTANCE;
    }

    @Override
    public SchemaFilter getDropFilter() {
        return MySchemaFilter.INSTANCE;
    }

    @Override
    public SchemaFilter getMigrateFilter() {
        return MySchemaFilter.INSTANCE;
    }

    @Override
    public SchemaFilter getValidateFilter() {
        return MySchemaFilter.INSTANCE;
    }
}

架构过滤器

public class MySchemaFilter implements SchemaFilter {

    public static final MySchemaFilter INSTANCE = new MySchemaFilter();

    @Override
    public boolean includeNamespace(Namespace namespace) {
        return true;
    }

    @Override
    public boolean includeTable(Table table) {
        if (table.getName().equals("customer")) {
            return false;
        }

        return true;
    }

    @Override
    public boolean includeSequence(Sequence sequence) {
        return true;
    }
}

Spring 属性配置

spring.jpa.properties.hibernate.hbm2ddl.schema_filter_provider=MySchemaFilterProvider

【讨论】：