How to read a properties file in Java? [duplicate]

Question

I am using servlets where I hard-code the database connection details, so if make any change I have to recompile the code. So instead I'd like to use a .properties file (which I can modify later) and use that as the source for my database connection.

The problem is I don't know how to read the property file. Could someone please help me to read the file?

Answer 1

   . . .
   // create and load default properties
   Properties defaultProps = new Properties();
   FileInputStream in = new FileInputStream("defaultProperties");
   defaultProps.load(in);
   in.close();

   // create application properties with default
   Properties applicationProps = new Properties(defaultProps);

   // now load properties from last invocation
   in = new FileInputStream("appProperties");
   applicationProps.load(in);
   in.close();
   . . .

Example is coming from here Properties (Java)

The methods of Properties can throw exceptions. - When the file path is not valid (FileNotFoundException). Please try to create a File object and check, whether the File is existing. - ...

Answer 2

You may take a look at Apache Commons Configuration. Using it you can read properties file like that:

Configuration config = new PropertiesConfiguration("user.properties");
String connectionUrl = config.getString("connection.url");

This information regarding file location may be also important:

If you do not specify an absolute path, the file will be searched automatically in the following locations:

• in the current directory
• in the user home directory
• in the classpath

So in case of reading properties file in a servlet you should put properties file in a classpath (e.g. in WEB-INF/classes).

You can find more examples at their website.

Answer 3

You can use java.util.Properties

Answer 4

The biggest problem in reading a property file in web application is that you actually don't know about the actaul path of the file. So we have to use the relative path and for that we have to use various functions and classes like getresourceAsStream(), InputStream, FileinputStream etc.

And the method getReourceAsStream behaves differently in static and non static methogs.. you can do this in below way

1. Non Static

   InputStream input = getClass().getClassLoader().getResourceAsStream("config.properties");

2. Static

   InputStream input = ReadPropertyFile.class.getClassLoader().getResourceAsStream("config.properties");

For complete reference you can follow these links..

http://www.codingeek.com/java/using-getresourceasstream-in-static-method-reading-property-files

http://www.codingeek.com/java/read-and-write-properties-file-in-java-examples/

Answer 5

InputStream in = Thread.currentThread().getContextClassLoader().getResourceAsStream("my.properties");
Properties p = new Properties();
p.load(in);
in.close();