My Wiki: How to read a properties file in a web application

My Wiki: How to read a properties file in a web application

How to read a properties file in a web application

The code to do this is pretty simple. But going by the number of people who keep asking this question, i thought i would post the code over here. Let's consider that you have a war file named SampleApp.war which has a properties file named myApp.properties at it's root :

SampleApp.war
   |
   |-------- myApp.properties
   |
   |-------- WEB-INF
                |
                |---- classes
                         |
                         |----- org
                                 |------ myApp
                                           |------- MyPropertiesReader.class
                                           

Let's assume that you want to read the property named "abc" present in the properties file:

----------------
myApp.properties:
----------------

abc=some value
xyz=some other value

Let's consider that the class org.myApp.MyPropertiesReader present in your application wants to read the property. Here's the code for the same:

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1. package org.myapp;  
2.   
3. import java.io.IOException;  
4. import java.io.InputStream;  
5. import java.util.Properties;  
6.   
7. /** 
8.  * Simple class meant to read a properties file 
9.  *  
10.  * @author Jaikiran Pai 
11.  *  
12.  */  
13. public class MyPropertiesReader {  
14.   
15.     /** 
16.      * Default Constructor 
17.      *  
18.      */  
19.     public MyPropertiesReader() {  
20.   
21.     }  
22.   
23.     /** 
24.      * Some Method 
25.      *  
26.      * @throws IOException 
27.      *  
28.      */  
29.     public void doSomeOperation() throws IOException {  
30.         // Get the inputStream  
31.         InputStream inputStream = this.getClass().getClassLoader()  
32.                 .getResourceAsStream("myApp.properties");  
33.   
34.         Properties properties = new Properties();  
35.   
36.         System.out.println("InputStream is: " + inputStream);  
37.   
38.         // load the inputStream using the Properties  
39.         properties.load(inputStream);  
40.         // get the value of the property  
41.         String propValue = properties.getProperty("abc");  
42.   
43.         System.out.println("Property value is: " + propValue);  
44.     }  
45.   
46. }  

package org.myapp;

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

/**
 * Simple class meant to read a properties file
 *
 * @author Jaikiran Pai
 *
 */
public class MyPropertiesReader {

    /**
     * Default Constructor
     *
     */
    public MyPropertiesReader() {

    }

    /**
     * Some Method
     *
     * @throws IOException
     *
     */
    public void doSomeOperation() throws IOException {
        // Get the inputStream
        InputStream inputStream = this.getClass().getClassLoader()
                .getResourceAsStream("myApp.properties");

        Properties properties = new Properties();

        System.out.println("InputStream is: " + inputStream);

        // load the inputStream using the Properties
        properties.load(inputStream);
        // get the value of the property
        String propValue = properties.getProperty("abc");

        System.out.println("Property value is: " + propValue);
    }

}

Pretty straight-forward. Now suppose the properties file is not at the root of the application, but inside a folder (let's name it config) in the web application, something like:

SampleApp.war
   |
   |-------- config
   |           |------- myApp.properties   
   |           
   |
   |-------- WEB-INF
                |
                |---- classes
                         |
                         |----- org
                                 |------ myApp
                                           |------- MyPropertiesReader.class
                                           

There will just be one line change in the above code:

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1. public void doSomeOperation() throws IOException {  
2.       //Get the inputStream-->This time we have specified the folder name too.  
3.       InputStream inputStream = this.getClass().getClassLoader()  
4.               .getResourceAsStream("config/myApp.properties");  
5.         
6.       Properties properties = new Properties();  
7.          
8.       System.out.println("InputStream is: " + inputStream);  
9.         
10.       //load the inputStream using the Properties  
11.       properties.load(inputStream);  
12.       //get the value of the property  
13.       String propValue = properties.getProperty("abc");  
14.         
15.       System.out.println("Property value is: " + propValue);  
16.   }  
17.     

  public void doSomeOperation() throws IOException {
        //Get the inputStream-->This time we have specified the folder name too.
        InputStream inputStream = this.getClass().getClassLoader()
                .getResourceAsStream("config/myApp.properties");

        Properties properties = new Properties();

        System.out.println("InputStream is: " + inputStream);

        //load the inputStream using the Properties
        properties.load(inputStream);
        //get the value of the property
        String propValue = properties.getProperty("abc");

        System.out.println("Property value is: " + propValue);
    }

That's all that is required to get it working.