Using properties files in Spring

Using properties files by MessageSource in Spring: In previous chapters we will discuss about ApplicationContext and BeanFactory. ApplicationContext has some extra functionalities in Spring Framework which Internatiolization, Messaging, Properties file etc.

1. Using org.springframework.context.MessageSource: 
Its using read message in the class files and display message as the output, below given example show how to use properties files with org.springframework.context.MessageSource.

myMessage.properties
greeting=Hello Dinesh!
drawing.circle=Circle is Drawn!

Now to read this properties file in the spring application we have to use the a class name "org.springframework.context.support.ResourceBundleMessageSource" this help to pick the properties files into to the application, this define as bean in the spring configuration file(spring.xml). As follows

spring.xml
<beans xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p" xmlns:security="http://www.springframework.org/schema/security" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.springframework.org/schema/beans" xsi:schemalocation="http://www.springframework.org/schema/beans">

<context:annotation-config> </context:annotation-config>
<context:component-scan base-package="com.dineshonjava.sdnext.tutorial.property"></context:component-scan>

<bean class="com.dineshonjava.sdnext.tutorial.property.Point" id="center">
 <property name="x" value="20"></property>
 <property name="y" value="0"></property>
</bean>
 
<bean class="org.springframework.context.support.ResourceBundleMessageSource" id="messageSource">
 <property name="basenames">
  <list>
      <value>myMessages</value>
  </list>
 </property>
</bean>

</beans>

Now "messageSource" using as property of the bean circle as follows:
Circle.java
package com.dineshonjava.sdnext.tutorial.property;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Component;

/**
 * @author Dinesh Rajput
 *
 */
@Component
public class Circle
{
 @Autowired
 private Point center;
 @Autowired
 private MessageSource messageSource;

 /**
  * @param messageSource the messageSource to set
  */
 public void setMessageSource(MessageSource messageSource) 
 {
  this.messageSource = messageSource;
 }

 /**
  * @param center the center to set
  */
 public void setCenter(Point center)
 {
  this.center = center;
 }

 public void draw()
 {
System.out.println(this.messageSource.getMessage("drawing.circle", null, "Default Drawing Greeting", null));
 }
}

In the above class file two property "center" and "messageSource" which autowired with the bean name "circle". We get the message of the properties file in the draw() method by using following method

org.springframework.context.MessageSource.getMessage(String arg0, Object[] arg1, String arg2, Locale arg3)

where String arg0 give the key of properties file to read its related message. 
as our example we are using "drawing.circle" and "greeting" as keys.

Object[] arg1 is the array of parameters which are applied to the properties file.

Example.
drawing.point=Circle: Point is: ({0}, {1})

Here there are two parameters {0}, {1} passes as

getMessage("drawing.point", new Object[]{center.getX(), center.getY()}, "Default Drawing Greeting", null)

Here center.getX() is replace with the {0}
and center.getY() is replace with the {1}

Point.java
package com.dineshonjava.sdnext.tutorial.property;

/**
 * @author Dinesh Rajput
 *
 */
public class Point 
{
 private int x;
 private int y;
 /**
  * @return the x
  */
 public int getX() 
 {
  return x;
 }
 /**
  * @param x the x to set
  */
 public void setX(int x) 
 {
  this.x = x;
 }
 /**
  * @return the y
  */
 public int getY()
 {
  return y;
 }
 /**
  * @param y the y to set
  */
 public void setY(int y)
 {
  this.y = y;
 } 
}

Now run the following class file.
DrawingApp.java
package com.dineshonjava.sdnext.tutorial.property;

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

/**
 * @author Dinesh Rajput
 *
 */
public class DrawingApp
{

 /**
  * @param args
  */
 public static void main(String[] args)
 {
ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
System.out.println(context.getMessage("greeting", null, "Default Greeting", null));
Circle circle = (Circle)context.getBean("circle");
shape.draw();
 }
}

If every thing ok then we get the following output:
Output:
Jul 18, 2012 9:04:33 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@758fc9: startup date [Wed Jul 18 21:04:33 IST 2012]; root of context hierarchy
Jul 18, 2012 9:04:33 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [spring.xml]
Jul 18, 2012 9:04:34 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1238bd2: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,circle,center,messageSource,org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor#0]; root of factory hierarchy
Hello Dinesh!
Circle is Drawn!

Using properties file with parameters:

myMessage.properties
greeting=Hello Dinesh!
drawing.circle=Circle is Drawn!
drawing.point=Circle: Point is: ({0}, {1})

Now make some change in the draw() method of Circle.java file.

public void draw()
{
System.out.println(this.messageSource.getMessage("drawing.circle", null, "Default Drawing Greeting", null));
System.out.println(this.messageSource.getMessage("drawing.point", new Object[]   {center.getX(), center.getY()}, "Default Drawing Greeting", null));
}

After make these change run the main application file then we get the following output:
Hello Dinesh!
Circle is Drawn!
Circle: Point is: (20, 0)


Using properties files in Spring

 

2. Using org.springframework.beans.factory.config.PropertyPlaceholderConfigurer:

If you need to read properties file in your Spring application all you need is to configure a PropertyPlaceholderConfigurer bean in your application context.
Following example shows how to read property values from a properties file named myMessage.properties. This file needs to be in your classpath so Spring can find it.

myMessage.properties
X-axis=20
Y-axis=0

spring.xml
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" id="placeholderConfig">    
<property name="location" value="classpath:myMessage.properties"> 
   
  </property>
</bean>  
<bean class="com.dineshonjava.sdnext.tutorial.property.Point" id="center">
 <property name="x" value="${X-axis}"></property>
 <property name="y" value="${Y-axis}"></property>
</bean>

Notice the placeholderConfig bean. This is where we are instructing Spring container to load the values from myMessage.properties file. You can name your will whatever you like.




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