[spring] 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?

Here is an additional answer that was also great help for me to understand how it worked : http://www.javacodegeeks.com/2013/07/spring-bean-and-propertyplaceholderconfigurer.html

any BeanFactoryPostProcessor beans have to be declared with a static, modifier

@Configuration
@PropertySource("classpath:root/test.props")
public class SampleConfig {
 @Value("${test.prop}")
 private String attr;
 @Bean
 public SampleService sampleService() {
  return new SampleService(attr);
 }

 @Bean
 public static PropertySourcesPlaceholderConfigurer placeHolderConfigurer() {
  return new PropertySourcesPlaceholderConfigurer();
 }
}

In configuration class

@Configuration
@PropertySource("classpath:/com/myco/app.properties")
public class AppConfig {
   @Autowired
   Environment env;

   @Bean
   public TestBean testBean() {
       TestBean testBean = new TestBean();
       testBean.setName(env.getProperty("testbean.name"));
       return testBean;
   }
}

Another way is using a ResourceBundle. Basically you get the bundle using its name without the '.properties'

private static final ResourceBundle resource = ResourceBundle.getBundle("config");

And you recover any value using this:

private final String prop = resource.getString("propName");

I'll recommend reading this link https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html from SpringBoot docs about injecting external configs. They didn't only talk about retrieving from a properties file but also YAML and even JSON files. I found it helpful. I hope you do too.

You need to put a PropertyPlaceholderConfigurer bean in your application context and set its location property.

See details here : http://www.zparacha.com/how-to-read-properties-file-in-spring/

You might have to modify your property file a bit for this thing to work.

Hope it helps.

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");
    }
}

I wanted an utility class which is not managed by spring, so no spring annotations like @Component, @Configuration etc. But I wanted the class to read from application.properties

I managed to get it working by getting the class to be aware of the Spring Context, hence is aware of Environment, and hence environment.getProperty() works as expected.

To be explicit, I have:

application.properties

mypath=somestring

Utils.java

import org.springframework.core.env.Environment;

// No spring annotations here
public class Utils {
    public String execute(String cmd) {
        // Making the class Spring context aware
        ApplicationContextProvider appContext = new ApplicationContextProvider();
        Environment env = appContext.getApplicationContext().getEnvironment();

        // env.getProperty() works!!!
        System.out.println(env.getProperty("mypath")) 
    }
}

ApplicationContextProvider.java (see Spring get current ApplicationContext)

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class ApplicationContextProvider implements ApplicationContextAware {
    private static ApplicationContext CONTEXT;

    public ApplicationContext getApplicationContext() {
        return CONTEXT;
    }

    public void setApplicationContext(ApplicationContext context) throws BeansException {
        CONTEXT = context;
    }

    public static Object getBean(String beanName) {
        return CONTEXT.getBean(beanName);
    }
}

 [project structure]: http://i.stack.imgur.com/RAGX3.jpg
-------------------------------
    package beans;

        import java.util.Properties;
        import java.util.Set;

        public class PropertiesBeans {

            private Properties properties;

            public void setProperties(Properties properties) {
                this.properties = properties;
            }

            public void getProperty(){
                Set keys = properties.keySet();
                for (Object key : keys) {
                    System.out.println(key+" : "+properties.getProperty(key.toString()));
                }
            }

        }
    ----------------------------

        package beans;

        import org.springframework.context.ApplicationContext;
        import org.springframework.context.support.ClassPathXmlApplicationContext;

        public class Test {

            public static void main(String[] args) {
                // TODO Auto-generated method stub
                ApplicationContext ap = new ClassPathXmlApplicationContext("resource/spring.xml");
                PropertiesBeans p = (PropertiesBeans)ap.getBean("p");
                p.getProperty();
            }

        }
    ----------------------------

 - driver.properties

    Driver = com.mysql.jdbc.Driver
    url = jdbc:mysql://localhost:3306/test
    username = root
    password = root
    ----------------------------



     <beans xmlns="http://www.springframework.org/schema/beans"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
               xmlns:util="http://www.springframework.org/schema/util"
               xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd">

            <bean id="p" class="beans.PropertiesBeans">
                <property name="properties">
                    <util:properties location="classpath:resource/driver.properties"/>
                </property>
            </bean>

        </beans>

If you need to manually read a properties file without using @Value.

Thanks for the well written page by Lokesh Gupta : Blog

package utils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.ResourceUtils;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import java.io.File;


public class Utils {

    private static final Logger LOGGER = LoggerFactory.getLogger(Utils.class.getName());

    public static Properties fetchProperties(){
        Properties properties = new Properties();
        try {
            File file = ResourceUtils.getFile("classpath:application.properties");
            InputStream in = new FileInputStream(file);
            properties.load(in);
        } catch (IOException e) {
            LOGGER.error(e.getMessage());
        }
        return properties;
    }
}