How to read values from properties file?

I am using spring. I need to read values from properties file. This is internal properties file not the external properties file. Properties file can be as below.

some.properties ---file name. values are below.

abc = abc
def = dsd
ghi = weds
jil = sdd

I need to read those values from the properties file not in traditional way. How to achieve it? Is there any latest approach with spring 3.0?

Solution 1:

Configure PropertyPlaceholder in your context:

<context:property-placeholder location="classpath*:my.properties"/>

Then you refer to the properties in your beans:

@Component
class MyClass {
  @Value("${my.property.name}")
  private String[] myValues;
}

To parse property with multiple comma-separated values:

my.property.name=aaa,bbb,ccc

If that doesn't work, you can define a bean with properties, inject and process it manually:

<bean id="myProperties"
      class="org.springframework.beans.factory.config.PropertiesFactoryBean">
  <property name="locations">
    <list>
      <value>classpath*:my.properties</value>
    </list>
  </property>
</bean>

and the bean:

@Component
class MyClass {
  @Resource(name="myProperties")
  private Properties myProperties;

  @PostConstruct
  public void init() {
    // do whatever you need with properties
  }
}

Solution 2:

There are various ways to achieve the same. Below are some commonly used ways in spring-

1. Using PropertyPlaceholderConfigurer

2. Using PropertySource

3. Using ResourceBundleMessageSource

4. Using PropertiesFactoryBean

   and many more........................

Assuming ds.type is key in your property file.

Using PropertyPlaceholderConfigurer

Register PropertyPlaceholderConfigurer bean-

<context:property-placeholder location="classpath:path/filename.properties"/>

or

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
  <property name="locations" value="classpath:path/filename.properties" ></property>
</bean>

or

@Configuration
public class SampleConfig {
 @Bean
 public static PropertySourcesPlaceholderConfigurer placeHolderConfigurer() {
  return new PropertySourcesPlaceholderConfigurer();
  //set locations as well.
 }
}

After registering PropertySourcesPlaceholderConfigurer, you can access the value-

@Value("${ds.type}")private String attr; 

Using PropertySource

In the latest spring version you don't need to register PropertyPlaceHolderConfigurer with @PropertySource, I found a good link to understand version compatibility-

@PropertySource("classpath:path/filename.properties")
@Component
public class BeanTester {
    @Autowired Environment environment; 
    public void execute() {
        String attr = this.environment.getProperty("ds.type");
    }
}

Using ResourceBundleMessageSource

Register Bean-

<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
  <property name="basenames">
    <list>
      <value>classpath:path/filename.properties</value>
    </list>
  </property>
</bean>

Access Value-

((ApplicationContext)context).getMessage("ds.type", null, null);

or

@Component
public class BeanTester {
    @Autowired MessageSource messageSource; 
    public void execute() {
        String attr = this.messageSource.getMessage("ds.type", null, null);
    }
}

Using PropertiesFactoryBean

Register Bean-

<bean id="properties"
      class="org.springframework.beans.factory.config.PropertiesFactoryBean">
  <property name="locations">
    <list>
      <value>classpath:path/filename.properties</value>
    </list>
  </property>
</bean>

Wire Properties instance into your class-

@Component
public class BeanTester {
    @Autowired Properties properties; 
    public void execute() {
        String attr = properties.getProperty("ds.type");
    }
}