如何从另一个Spring Boot应用程序访问一个Spring Boot应用程序的内存h2数据库

问题描述：

在我的项目中，我创建了3个spring boot应用程序.第一个spring boot应用程序具有h2嵌入式数据库.现在，我想直接从第二和第三次Spring Boot应用程序访问此数据库，而无需编写任何服务来获取此数据.那么谁能告诉我如何做到这一点?

In my project, i have created 3 spring boot application. First spring boot application has h2 embedded database. Now i want to access this database from my 2nd and 3rd spring boot application directly without writing any services to get this data. So can anyone tell me how can i achieve this?

答

您可以将H2 Server设置为Spring Bean.

You can setup H2 Server as Spring Bean.

首先编辑pom.xml-从h2依赖项中删除<scope>runtime</scope>:

First edit pom.xml - delete <scope>runtime</scope> from h2 dependency:

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
</dependency>

然后将H2服务器bean添加到SpringBootApplication或Configuration类:

Then add H2 server bean to SpringBootApplication or Configuration class:

@SpringBootApplication
public class Application {

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

    /**
     * Start internal H2 server so we can query the DB from IDE
     *
     * @return H2 Server instance
     * @throws SQLException
     */
    @Bean(initMethod = "start", destroyMethod = "stop")
    public Server h2Server() throws SQLException {
        return Server.createTcpServer("-tcp", "-tcpAllowOthers", "-tcpPort", "9092");
    }
}

最后-编辑application.properties-设置数据库名称:

Last - edit application.properties - set the name of the database:

spring.datasource.url=jdbc:h2:mem:dbname
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=create

然后，您可以使用以下连接从外部连接到此H2服务器(例如，使用H2 DB连接到您的应用程序):

Then you can connect to this H2 Server from outside (e.g. to your application with H2 DB) using this connection:

jdbc:h2:tcp://localhost:9092/mem:dbname

作为奖励，使用此URL，您可以直接从IDE连接到应用程序的数据库.

As a bonus using this url you can connect to the database of your app right from your IDE.

更新

尝试连接到1.5.x版本的Spring Boot应用程序的H2时，可能会出现错误.在这种情况下，只需将H2的版本更改为以前的版本即可，例如:

There is a chance of getting an error when trying to connect to the H2 for Spring Boot app of 1.5.x version. In this case just change a version of H2 to previous one, for example:

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>1.4.193</version>
</dependency>

更新2

如果需要在同一主机上同时运行多个具有H2的应用程序，则应在Server.createTcpServer方法中设置它们上不同的H2端口，例如:9092、9093等.

If you need to run several apps with H2 simultaneously on the same host you should set the different H2 ports on them in Server.createTcpServer mothod, for example: 9092, 9093, etc..

// First App
@Bean(initMethod = "start", destroyMethod = "stop")
public Server h2Server() throws SQLException {
    return Server.createTcpServer("-tcp", "-tcpAllowOthers", "-tcpPort", "9092");
}

// Second App
@Bean(initMethod = "start", destroyMethod = "stop")
public Server h2Server() throws SQLException {
    return Server.createTcpServer("-tcp", "-tcpAllowOthers", "-tcpPort", "9093");
}

然后，您可以使用以下网址连接到这些应用程序的H2 DB:

Then you can connect to the H2 DB of these apps with following urls:

App1 H2: jdbc:h2:tcp://localhost:9092/mem:dbname
App2 H2: jdbc:h2:tcp://localhost:9093/mem:dbname

如何从另一个Spring Boot应用程序访问一个Spring Boot应用程序的内存h2数据库

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