de.weltraumschaf.config

Class ReloadingPropertiesConfiguration

java.lang.Object

de.weltraumschaf.config.ReloadingPropertiesConfiguration

public abstract class ReloadingPropertiesConfiguration
extends Object

This configuration is a Java properties file based configuration, which reloads its content if the properties file has changed.

This configuration does not need you to force an application restart, if you changed the properties file.

Based on this blog post.

Example:

 final class MyAppConfig extends ReloadingPropertiesConfiguration {

     public MyAppConfig(final Path file) {
         super(file);
     }

     public String getServiceUrl() {
          return getRequiredProperty("service.url");
     }

     public boolean getShouldStartSlow() {
          return getFlag("start-slow", false);
     }

     public int getHttpPort(final int defaultPort) {
          return getInteger("myapp.http.port", defaultPort);
     }

 }
 
 

This class is thread safe because the method reading the file is synchronized.

Since:

1.1.0

Author:

Sven Strittmatter

Field Summary

Fields

Modifier and Type	Field and Description
private Path	configFile Where the configuration is loaded from.
private long	lastLoad Time in milliseconds.
private Properties	properties Holds the configuration values.

Constructor Summary

Constructors

Constructor and Description
ReloadingPropertiesConfiguration(File file) Convenience constructor for file.
ReloadingPropertiesConfiguration(Path file) Dedicated constructor.
ReloadingPropertiesConfiguration(String filename) Convenience constructor for file name as string.

Method Summary

Methods

Modifier and Type	Method and Description
private void	ensureConfigurationIsFresh() Reads the property file from disk if the files modification date is after the last one read.
boolean	getFlag(String propertyName, boolean defaultValue) Get a boolean property by name.
int	getInteger(String propertyName, int defaultValue) Get a integer property by name.
private String	getProperty(String propertyName) Get the property from the underlying object and ensures it is fresh loaded.
String	getProperty(String propertyName, String defaultValue) Get a property by name.
String	getRequiredProperty(String propertyName) Get a property by name.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

properties

private final Properties properties

Holds the configuration values.

configFile

private final Path configFile

Where the configuration is loaded from.

lastLoad

private long lastLoad

Time in milliseconds.

Initial -1 so that file will be read anyway on first property access.

Constructor Detail

ReloadingPropertiesConfiguration

public ReloadingPropertiesConfiguration(String filename)

Convenience constructor for file name as string.

Parameters:

filename - must not be null or empty

ReloadingPropertiesConfiguration

public ReloadingPropertiesConfiguration(File file)

Convenience constructor for file.

Parameters:

file - must not be null

ReloadingPropertiesConfiguration

public ReloadingPropertiesConfiguration(Path file)

Dedicated constructor.

Parameters:

file - must not be null

Method Detail

getProperty

public final String getProperty(String propertyName,
                 String defaultValue)

Get a property by name.

If the property does not exist then the default value will be returned.

Parameters:

propertyName - must not be null or empty

defaultValue - must not be null

Returns:

never null

getRequiredProperty

public final String getRequiredProperty(String propertyName)

Get a property by name.

Throws a RuntimeException if property does not exists.

Parameters:

propertyName - must not be null or empty

Returns:

never null

getFlag

public final boolean getFlag(String propertyName,
              boolean defaultValue)

Get a boolean property by name.

This method calls getProperty(java.lang.String, java.lang.String). The result will be passed through Boolean.parseBoolean(java.lang.String).

Parameters:

propertyName - must not be null or empty

defaultValue - must not be null

Returns:

never null

getInteger

public final int getInteger(String propertyName,
             int defaultValue)

Get a integer property by name.

This method calls getProperty(java.lang.String, java.lang.String). The result will be passed through Integer.parseInt(java.lang.String, int) with radix of 10.

Parameters:

propertyName - must not be null or empty

defaultValue - must not be null

Returns:

never null

getProperty

private String getProperty(String propertyName)

Get the property from the underlying object and ensures it is fresh loaded.

Parameters:

propertyName - must not be null or empty

Returns:

never null

ensureConfigurationIsFresh

private void ensureConfigurationIsFresh()

Reads the property file from disk if the files modification date is after the last one read.