How to start HSQLDB in server mode from Spring boot application - spring

Question

I have a Spring boot application, running with jpa data and hsqldb 2.3.3 (in Centos 7), the application runs fine but I would like to use HSQLDB database manager to check the data status, however it failed:
application.properties:
spring.datasource.url=jdbc:hsqldb:mem:testdb
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.HSQLDialect
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=create
Command to start HSQLDB:
java -cp /home/mycentos/.m2/repository/org/hsqldb/hsqldb/2.3.3/hsqldb-2.3.3.jar org.hsqldb.util.DatabaseManagerSwing
If I tried to log in with HSQLDB server mode, it pops Connection refused error
jdbc:hsqldb:hsql://localhost/testdb
If I tried to log in in-memory db, I can log in but no table and data showing up
jdbc:hsqldb:hsql:testdb
Question:
How to make it works?
Do I have to refer to the hsqldb.jar from tomcat deployment folder because that is the one using by the application?
Any configuration difference to configure hsqldb in server mode or in-memory mode from Spring application?
Can any method make in-memory mode working in such situation (to check data by db created Spring boot)?

Answer 1

To access the HSQL DB created by Spring boot app, you have to start HSQL server. For example, create a XML configuration file hsql_cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<bean id="hqlServer" class="org.hsqldb.server.Server" init-method="start" destroy-method="stop">
<property name="properties"><bean class="org.hsqldb.persist.HsqlProperties">
<constructor-arg><props>
<prop key="server.database.0">mem:testdb</prop>
<prop key="server.dbname.0">testdb</prop><!--DB name for network connection-->
<prop key="server.no_system_exit">true</prop>
<prop key="server.port">9001</prop><!--default port is 9001 -->
</props></constructor-arg>
</bean></property>
</bean>
</beans>
Here is a example to import the XML configuration in main application class.
#SpringBootApplication
#ImportResource(value="classpath:/package/hsql_cfg.xml")
public class MyApplication {
}
The HSQL server will start with Spring boot app. Other applications could connect to the HSQL server using JDBC url
jdbc:hsqldb:hsql://ip_address:port/testdb
Of course, hsqldb.jar is required for loading JDBC driver class.

Answer 2

Just to add to beckyang's answer, here is my approach.
Includes a hack to redirect logs to slf4j.
Includes specifying a corresponding datasource.
import org.hsqldb.jdbc.JDBCDataSource;
import org.hsqldb.server.Server;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import javax.sql.DataSource;
import java.io.ByteArrayOutputStream;
import java.io.PrintWriter;
#Configuration
public class DataSourceConfiguration {
private final Logger log = LoggerFactory.getLogger(getClass());
#Bean(initMethod = "start", destroyMethod = "stop")
#ConfigurationProperties//(prefix = "alarms.idempotent.server")
public Server idempotentServer(#Value("${alarms.idempotent.server.path}") String path, #Value("${alarms.idempotent.port}") int port, #Value("${alarms.idempotent.name}") String name) {
Server server = new Server();
server.setDatabaseName(0, name);
server.setDatabasePath(0, path);
server.setPort(port);
server.setLogWriter(slf4jPrintWriter());
server.setErrWriter(slf4jPrintWriter());
return server;
}
#Bean("idempotentDataSource")
#Primary
#ConfigurationProperties
public DataSource idempotentDataSource(#Value("${alarms.idempotent.datasource.url}") String urlNoPath, #Value("${alarms.idempotent.name}") String name) {
JDBCDataSource jdbcDataSource = new JDBCDataSource();
String url = urlNoPath;
if (!url.endsWith("/")) {
url += "/";
}
url += name;
jdbcDataSource.setUrl(url);
jdbcDataSource.setUser("sa");
return jdbcDataSource;
}
private PrintWriter slf4jPrintWriter() {
PrintWriter printWriter = new PrintWriter(new ByteArrayOutputStream()) {
#Override
public void println(final String x) {
log.debug(x);
}
};
return printWriter;
}
}