Spring Web Application: doing something on startup (initialization)

Question

I want to fill some tables of my DB from a text file on startup, I want my initialization method to be called only when my application do start.

I am using Spring (+MVC) and Hibernate with MySQL.

how can I do?

Answer 1

You can create an application listener, it's designed specifically for such needs. In this case it will be executed every time context is started (or refreshed).

@Component
public class DatabaseFillerOnStartup implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
        ...
    }
}

Answer 2

Hibernate comes with an way to add some files with sql statements that will be executed on startup.

The parameter is hibernate.hbm2ddl.import_files.

@See Hibernate Reference: Chapter 3.4. Optional configuration properties

• Table 3.7. Miscellaneous Properties
• hibernate.hbm2ddl.import_files:

Comma-separated names of the optional files containing SQL DML statements executed during the SessionFactory creation. This is useful for testing or demoing: by adding INSERT statements for example you can populate your database with a minimal set of data when it is deployed.

File order matters, the statements of a give file are executed before the statements of the following files. These statements are only executed if the schema is created ie if hibernate.hbm2ddl.auto is set to create or create-drop.

e.g. /humans.sql,/dogs.sql

I fond some hints that this may only work if hibernate is started in 'create' mode. But I am not sure.

Answer 3

Use the postconstuct annotation somewhere inside a bean :

@PostConstruct
public void init() {
     //startup logic here
}

Probably makes (desgin) sense to use a configuration bean, but it can be any bean at all.

Answer 4

Two options,

First: Let hibernate create your ddl everytime the services is startup(Only for local or dev environment)

<bean id="hibernateVendor" class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
      p:showSql="false"
      p:generateDdl="true"/>

Or create in spring a Bean with init-lazy false and add in there the logic to create the database if you dont have it or inject your script, or do whatever you want.

 <bean id="bootstrapStartup" class="com.tscompany.rest.bootstrap.BootstrapStartup" lazy-init="false" init-method="init"/>

Answer 5

You can create some bean in root-context configuration - like

<bean id="someBean" class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
    <property name="someProperty">
        ... description of the property
    </property>
    <property name="targetMethod" value="methodName" />
</bean>

Thus - on application startup method "methodName" will be invoked. We have DB upgrades implemented in such a way.

Answer 6

If you have your hibernate.hbm2ddl.auto property set to create or create-drop then the easiest way to do that is by setting hibernate.hbm2ddl.import_files property with SQL file name that contains SQL statements to load your initial data into the database schema, e.g. initial application users.

The following is an example method that I have in my DatabaseConfig class. It sets hibernate.hbm2ddl.import_files property with SQL file name import_initial_data.sql that contains SQL Insert statements to load my initial data to the database schema.

   @Bean
   public LocalSessionFactoryBean hibernate5SessionFactoryBean(){
      LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
      localSessionFactoryBean.setDataSource((DataSource) appContext.getBean("DataSource"));
      localSessionFactoryBean.setAnnotatedClasses( AppUser.class );
      Properties properties = new Properties();
      properties.put( "hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
      properties.put("hibernate.hbm2ddl.auto","create-drop");
      properties.put("hibernate.hbm2ddl.import_files", "import_initial_data.sql");
      properties.put("hibernate.show_sql","true");
      localSessionFactoryBean.setHibernateProperties(properties);
      return localSessionFactoryBean;
   }

This is my AppUser.java in model package:

package com.beniregev.model;

import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.NoArgsConstructor;
import javax.persistence.*;

@Entity
@NoArgsConstructor(access = AccessLevel.PUBLIC)
@AllArgsConstructor(access = AccessLevel.PUBLIC)
public class AppUser {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private int id;
   @Column(nullable = false, unique = true)
   private String userName;
   @Column(nullable = false)
   private String password;

   public AppUser(String userName, String password) {
      this.userName = userName;
      this.password = password;
   }
}

Maven dependency for lombok:

<dependency>
   <groupId>org.projectlombok</groupId>
   <artifactId>lombok</artifactId>
   <version>1.16.6</version>
   <scope>provided</scope>
</dependency>

The import_initial_data.sql file that I have in resources directory:

INSERT INTO appuser(username, password) VALUES ('jesus', 'christ');
INSERT INTO appuser(username, password) VALUES ('mary', 'virgin');
INSERT INTO appuser(username, password) VALUES ('josef', 'who?');
INSERT INTO appuser(username, password) VALUES ('jeremaia', 'profet');
COMMIT;

And the result of *SELECT * FROM appuser;*: