Java code commonly needs to query system properties for configuration. Often, these checks are given default values to use if the property is not set.
The problem comes when code is run under a
SecurityManager
that denies the property read attempts. Instead of the null that is expected from trying
to read a property that does not exist, a
SecurityException
is thrown, stopping the execution of the application.
The following code is often used to read a property. But this code either requires time-consuming discovery of the properties to be read and changes to the security policy to allow the read, or it will simply fail and not be able to run under a Security Manager.
String value = System.getProperty("key");The proper way to read a system property requires the read to be wrapped in a try so that failures
are caught and dealt with. While correct, sprinkling this all over your code results in a lower
signal to noise ratio and makes it harder to see at a glance what is done:
String value = null;
try {
value = System.getProperty("key");
} catch(SecurityException e) {
}PropertyUtils allows you to not care why the property read failed and just continue on as though the property was not set. It eliminates boilerplate required for robustly reading a property value.
When property reads fail either because the property is not set or because the SecurityManager
denied the read attempt a null or a default value will be returned. No exceptions are thrown
and code can ignore that it may be running under a restrictive SecurityManager.
import com.eagen.propertyutils.PropertyUtils;
String value = PropertyUtils.getSystemProperty("key");
String val_or_default = PropertyUtils.getSystemProperty("key", "default");