What are the good ways to configure database connection? - spring

Question

I placed the database configuration inside a configuration class :
#Configuration
#ComponentScan("com.ambre.pta")
#EnableTransactionManagement
#PropertySources({
#PropertySource("classpath:fr/referentiel.properties")
})
public class ApplicationContextConfig {
#Autowired
private Environment env;
#Bean
public static PropertySourcesPlaceholderConfigurer properties() {
return new PropertySourcesPlaceholderConfigurer();
}
#Bean(name = "viewResolver")
public InternalResourceViewResolver getViewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setPrefix("/WEB-INF/views/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
#Bean(name = "dataSource")
public DataSource getDataSource() {
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName("oracle.jdbc.driver.OracleDriver");
dataSource.setUrl("jdbc:oracle:thin:#192.168.1.123:1521:xe");
dataSource.setUsername("pta");
dataSource.setPassword("pta");
return dataSource;
}
...
}
The problem is that everytime the project will be delivered to a different customer then the developer has to modify these configs and rebuild the project and finally regenrate the war file.
So are there simple procedures to change database configs without rebuilding nor regenerating the war file ?

Answer 1

You can move DB configuration into external properties.
Add something like this
#PropertySources({
#PropertySource("classpath:fr/referentiel.properties")
#PropertySource("${db.properties}")
})
and then when you run your application just add this parameter (notice 'file:' prefix)
-Ddb.properties=file:/path-to.properties
you can access db properties in your config like this
#Autowired
private Environment env;
...
dataSource.setDriverClassName(env.getProperty("db.driver"));
dataSource.setUrl(env.getProperty("db.url"));
dataSource.setUsername(env.getProperty("db.username"));
dataSource.setPassword(env.getProperty("db.password"));
or with #Value annotation, e.g.
#Value("${db.driver}")
private String dbDriver;
Properties file path-to.properties should be just a regular properties file. So
db.driver=oracle.jdbc.driver.OracleDriver
db.url=jdbc:oracle:thin:#192.168.1.123:1521:xe
db.username=pta
db.password=pta

Answer 2

I suggest you to use Spring boot which provides out of the box template projects. Also, setting up db connection in a Spring boot app is very simple. These are the two ways I have used so far.
If you want an in memory database, you can just include H2/HSQLDB/DERBY dependency in you pom.xml file and you are good to go. Spring boot sees these dependencies in you pom and creates a data source out of the box for you. One downside with these databases is they don't provide persistent storage.
If you want a persistent storage, like PostgreSQL, you can include the dependency in your pom.xml file and maintain a application.properties file inside your /src/main/resources folder.
For example, if you have a postgresql database track-courier running on your local machine on port 5432, the contents of this file will look something like below
spring.datasource.url=jdbc:postgresql://localhost:5432/track-courier
spring.datasource.username=postgres
spring.datasource.password=postgres
spring.jpa.hibernate.ddl-auto=update
And you don't need to manually create any data source bean in a configuration class. Spring boot take care of that out of the box. You can look at this link for reference.

Answer 3

You can use datasource for connecting to DB.
Below is sample code to connect database using data souce.
#Bean
public DataSource dataSource_aw_es() {
DataSource dataSource = null;
Context ctx = null;
try {
ctx = new InitialContext();
dataSource = (DataSource) ctx.lookup("java:/comp/env/jdbc/DataSourcename");
} catch (NamingException e) {
}
return dataSource;
}
You just need to configure data source in your server.
Most important is , no need to share the db credentials to connect to DB.
Below is configuration for data source on server.(Below configuartion is for Tomcat server.We need to configure below snippet in context.xml of tomcat server.)
<Resource name="jdbc/DataSourceName" auth="Container" type="javax.sql.DataSource"
maxActive="-1" maxIdle="-1" maxWait="-1"
username="user" password="password"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://IP_DB:7011/Schema_name"/>