Configure Datasource
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In order to use Hibernate, Jdbc, or JPA similar persistence framework or tools, you have to configure a java.sql.DataSource
for it.
Spring DataSource support is available in sring-jdbc
. Added it into your pom.xml.
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
</dependency>
A simple DataSouce
configuration looks like.
@Configuration
public class DataSourceConfig {
@Bean
public DataSource testDataSource() {
BasicDataSource bds = new BasicDataSource();
bds.setDriverClassName("com.mysql.jdbc.Driver");
bds.setUrl("jdbc:mysql://localhost:3306");
bds.setUsername("jdbc.username");
bds.setPassword("jdbc.password");
return bds;
}
}
Here, I uses Apache Commons Dbcp's BasicDataSource
to build a DataSource
. It is configured for MySQL database, before use it, do not forget to add mysql driver into pom.xml.
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
Declares this configuration class in getRootConfigClasses
method of AppInitializer
.
In above codes, we set username, password etc in hard codes, but in a real application, it is better to externalize these configurations into a property file.
Create another @configuration
class for this purpose.
@Configuration
@ComponentScan(
basePackageClasses = {Constants.class},
excludeFilters = {
@Filter(
type = FilterType.ANNOTATION,
value = {
RestController.class,
ControllerAdvice.class,
Configuration.class
}
)
}
)
@PropertySource("classpath:/app.properties")
@PropertySource(value = "classpath:/database.properties", ignoreResourceNotFound = true)
public class AppConfig {
}
AppConfig
work as an entr configuration for this application. @ComponentScan
use a fitler to load all none web components.
Use @PropertySource
to load the external properties files, app.properties
is use for application properties, and database.properties for holding database datasource properties.
jdbc.url=@jdbc.url@
jdbc.username=@jdbc.username@
jdbc.password=@jdbc.password@
hibernate.dialect=@hibernate.dialect@
In DataSouce configuration, use Environment
to fetch these properties.
private static final String ENV_JDBC_PASSWORD = "jdbc.password";
private static final String ENV_JDBC_USERNAME = "jdbc.username";
private static final String ENV_JDBC_URL = "jdbc.url";
@Inject
private Environment env;
@Bean
public DataSource testDataSource() {
BasicDataSource bds = new BasicDataSource();
bds.setDriverClassName("com.mysql.jdbc.Driver");
bds.setUrl(env.getProperty(ENV_JDBC_URL));
bds.setUsername(env.getProperty(ENV_JDBC_USERNAME));
bds.setPassword(env.getProperty(ENV_JDBC_PASSWORD));
return bds;
}
Spring Jdbc provides a simple EmbeddedDatabaseBuilder
to build an embedded datasource on the fly way.
@Bean
public DataSource dataSource() {
return new EmbeddedDatabaseBuilder()
.setType(EmbeddedDatabaseType.H2)
.build();
}
Here we build an embedded H2 datasource.
An embedded datasource is every helpful for development stage, everytime when we run the application, or run the tests, we are getting a fresh runtime environment.
Spring Jdbc also provides other built-in DataSource, such as DriverManagerDataSource, and some application server specific DataSource, eg. for Webphere.
For a production runtime environment, we should use pooled datasource, such as Apache Commons Dbcp, or application server built-in DataSource to get better performance.
We have discussed the usages of Apache Commons Dbcp earlier, you can add extra pool configuration for this datasource.
For application server built-in DataSource, Spring can access it via a Jndi proxy. Firstly configure a Jndi DataSource in appliation server GUI, then defines JndiObjectFactoryBean
to access it via Jndi name.
@Bean
public DataSource prodDataSource() {
JndiObjectFactoryBean ds = new JndiObjectFactoryBean();
ds.setLookupOnStartup(true);
ds.setJndiName("jdbc/postDS");
ds.setCache(true);
return (DataSource) ds.getObject();
}
The complete codes of DataSouceConfig
.
@Configuration
public class DataSourceConfig {
private static final String ENV_JDBC_PASSWORD = "jdbc.password";
private static final String ENV_JDBC_USERNAME = "jdbc.username";
private static final String ENV_JDBC_URL = "jdbc.url";
@Inject
private Environment env;
@Bean
@Profile("dev")
public DataSource dataSource() {
return new EmbeddedDatabaseBuilder()
.setType(EmbeddedDatabaseType.H2)
.build();
}
@Bean
@Profile("staging")
public DataSource testDataSource() {
BasicDataSource bds = new BasicDataSource();
bds.setDriverClassName("com.mysql.jdbc.Driver");
bds.setUrl(env.getProperty(ENV_JDBC_URL));
bds.setUsername(env.getProperty(ENV_JDBC_USERNAME));
bds.setPassword(env.getProperty(ENV_JDBC_PASSWORD));
return bds;
}
@Bean
@Profile("prod")
public DataSource prodDataSource() {
JndiObjectFactoryBean ds = new JndiObjectFactoryBean();
ds.setLookupOnStartup(true);
ds.setJndiName("jdbc/postDS");
ds.setCache(true);
return (DataSource) ds.getObject();
}
}
Three DataSouce beans are configured. Do not worry about the @Profile
annotation, I will explain it in a Spring Profile related section for it.