org.yarnandtail.andhow.load.std

Class StdPropFileOnFilesystemLoader

java.lang.Object

org.yarnandtail.andhow.load.BaseLoader

org.yarnandtail.andhow.load.PropFileBaseLoader

org.yarnandtail.andhow.load.PropFileOnFilesystemLoader

org.yarnandtail.andhow.load.std.StdPropFileOnFilesystemLoader

All Implemented Interfaces:

Loader, LocalFileLoader, ReadLoader, StandardLoader

public class StdPropFileOnFilesystemLoader
extends PropFileOnFilesystemLoader
implements StandardLoader

Parses and loads Properties from a Java .property file on the file system. Since file systems vary, there is no default filepath that AndHow attempts to load from.

Position in Standard Loading Order, first to last

• StdFixedValueLoader
• StdMainStringArgsLoader
• StdSysPropLoader
• StdEnvVarLoader
• StdJndiLoader
• StdPropFileOnFilesystemLoader <-- This loader
• StdPropFileOnClasspathLoader

Property value loading is based on a 'first win' strategy, so the first loader to find a value for a property sets the value.

Typical Use Case

A service application might load minimal configuration from system properties or environmental variables, loading the bulk of its configuration from a properties file on the file system. The properties file is not part of the application, so it survives redeployments. A single environmental or system property could then be used to specify the properties file.

Basic Behaviors

• Pre-trims String values: No (Individual Properties may still trim values)
• Complains about unrecognized properties: Yes
• Complains if the .properties file is missing: Yes (if a file path is configured)
• Default behavior: None - If not explicitly configured, no default loading is attempted.

Loader Details and Configuration

This loader reads properties files using the java.util.Properties, which silently ignores duplicate property entries (i.e., the same key appearing multiple times). When there are duplicate property keys in a properties file, only the last assigned value is used. Full details on how Java parses properties files can be found in the properties file specification.

This loader is only active if it is configured as shown below:

 import org.yarnandtail.andhow.*;
 import org.yarnandtail.andhow.property.StrProp;
 
 public class UsePropertyFileOnFilesystem implements AndHowInit {
   public static final StrProp MY_FILEPATH = StrProp.builder()
     .desc("Path to a properties file on the file system. "
       + "If a path is configured, startup will FAIL if the file is missing.").build();
 
    @Override
   public AndHowConfiguration getConfiguration() {
     return  StdConfig.instance()
       .setFilesystemPropFilePath(MY_FILEPATH);
   }
 }
 

The code above adds the property MY_FILEPATH (the name is arbitrary) which is used to configure the StdPropFileOnFilesystemLoader with a custom property file location. When AndHow initializes, the StdPropFileOnFilesystemLoader checks to see if a value has been loaded for MY_FILEPATH by any prior loader. If a value is present, the loader tries to load from the configured file system path. If no value is configured, this loader is skipped.

This is a Standard Loader

Like all StandardLoader's, this loader is intended to be auto-created by AndHow. The set of standard loaders and their order can bet set via the AndHowConfiguration.setStandardLoaders() methods. Other loaders which don't implement the StandardLoader interface can be inserted into the load order via the AndHowConfiguration.insertLoaderBefore/After().

Author:

eeverman

Field Summary

Fields inherited from class org.yarnandtail.andhow.load.PropFileBaseLoader

missingFileAProblem, pathProp, pathStr, unknownPropertyAProblem

Constructor Summary

Constructors

Constructor and Description
StdPropFileOnFilesystemLoader() There is no reason to use the constructor in production application code because AndHow creates a single instance on demand at runtime.

Method Summary

Methods inherited from class org.yarnandtail.andhow.load.PropFileOnFilesystemLoader

getSpecificLoadDescription, load, load

Methods inherited from class org.yarnandtail.andhow.load.PropFileBaseLoader

getConfigSamplePrinter, getEffectivePath, getInstanceConfig, getLoaderDialect, getLoaderType, isFlaggable, isMissingFileAProblem, isTrimmingRequiredForStringValues, isUnknownPropertyAProblem, loadInputStreamToProps, setFilePath, setFilePath, setMissingFileAProblem, setUnknownPropertyAProblem

Methods inherited from class org.yarnandtail.andhow.load.BaseLoader

attemptToAdd, attemptToAdd, attemptToAdd, attemptToAddIfNotDuplicate, createValue, findDuplicateProperty, getClassConfig, mapNametoProperty, releaseResources

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.yarnandtail.andhow.api.Loader

getClassConfig, getConfigSamplePrinter, getInstanceConfig, getLoaderDialect, getLoaderType, getSpecificLoadDescription, isFlaggable, isTrimmingRequiredForStringValues, load, releaseResources

Constructor Detail

StdPropFileOnFilesystemLoader

public StdPropFileOnFilesystemLoader()

There is no reason to use the constructor in production application code because AndHow creates a single instance on demand at runtime.