Loader (AndHow 0.3.0 API)

All Known Implementing Classes:

BaseLoader, EnviromentVariableLoader, FixedValueLoader, JndiLoader, PropertyFileBaseLoader, PropertyFileOnClasspathLoader, PropertyFileOnFilesystemLoader, StringArgumentLoader, SystemPropertyLoader
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public interface Loader
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Each instance is responsible for loading values from a particular type of source. Implementations may define a set of Properties used to control the behavior of all instances of a loader, which are returned from getClassConfig(). During AndHow startup, these parameters will be automatically added to the list of registered Properties. Values for these properties need to be loaded by a preceding loader or forced in the AndHowBuilder. Implementations may also define instance level configuration by returning a list of Properties from getInstanceConfig(). These properties must have been added to the groups added to the AndHow builder via addGroup(). Instances should not hold state because they are held in memory for the life of the application.

Author:

eeverman

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`Class<? extends BasePropertyGroup>`	`getClassConfig()` A group of Properties used to globally configure all instance of a type of loader.
`SamplePrinter`	`getConfigSamplePrinter()` Returns a ConfigSamplePrinter, which can be used to print a configuration sample for this Loader.
`List<Property>`	`getInstanceConfig()` A list of properties that the user has specified as being configuration properties for this Loader.
`String`	`getLoaderDialect()` The type dialect of the loader.
`String`	`getLoaderType()` The type of the loader, such as JNDI, PropertyFile, SystemProperty, etc..
`String`	`getSpecificLoadDescription()` For this particular load, where was info loaded from? This may vary from run to run based on config params.
`boolean`	`isTrimmingRequiredForStringValues()` If true, values for string properties are trimmed by the Trimmer of the property they are associated with.
`boolean`	`isUnrecognizedPropertyNamesConsideredAProblem()` If true, an unrecognized name is considered a problem that will stop application startup.
`LoaderValues`	`load(ConstructionDefinition runtimeDef, ValueMapWithContext existingValues)` Builds up a list of LoaderValues by loading property values from a configuration source.

- Method Detail
  - load
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LoaderValues load(ConstructionDefinition runtimeDef,
                  ValueMapWithContext existingValues)
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    Builds up a list of LoaderValues by loading property values from a configuration source.
    
    Parameters:
    
    runtimeDef -
    
    existingValues -
    
    Returns:
  - getClassConfig
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Class<? extends BasePropertyGroup> getClassConfig()
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    A group of Properties used to globally configure all instance of a type of loader. For loaders that are intended to be single instance (i.e. a JNDI loader) or loaders that can be multi-instance (PropertyFile loaders) but need to share some common configuration can return a BasePropertyGroup from this method that is their global configuration interface. For configuration properties that should vary between instances of the same loader class, accept them in the Loader constructor. (See getInstanceConfig) The BasePropertyGroup returned from this method will be included in sample config files. It is up to the Loader class to read from those configured properties if the user configures them.
    
    Returns:
  - getInstanceConfig
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List<Property> getInstanceConfig()
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    A list of properties that the user has specified as being configuration properties for this Loader. Typically these Properties have been specified in the Loader constructor or builder. An example usage would be passing in a Property that specifies the location of a properties file to read from. This is the preferred way to configure a loader because its clear to the user and it allows each instance of a loader to be configured differently, e.g., so PropertyFile loaders that load from different locations. Any Properties returned from this method must have been registered for configuration.
    
    Returns:
    
    Never null. Either an empty list or populated.
  - getSpecificLoadDescription
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String getSpecificLoadDescription()
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    For this particular load, where was info loaded from? This may vary from run to run based on config params. For instance, The PropFileLoader will look multiple places to find a properties file. This method should return the actual location it was found. Assume the text is prefixed with "This loader loaded from: ". An example would be "/home/user/config/my-props.properties" No ending punctuation should be used.
    
    Returns:
  - isTrimmingRequiredForStringValues
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boolean isTrimmingRequiredForStringValues()
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    If true, values for string properties are trimmed by the Trimmer of the property they are associated with. If false, no trimming is done. Non-String type property values (like Integer or Date type values) are not affected by this. Loaders that read from text files need to trim values to separate white space and carriage returns from the value. Loaders that read from more tightly defined sources, like reading properties from java.lang.System.getProperties(), can assume that trimming has already happened.
    
    Returns:
  - isUnrecognizedPropertyNamesConsideredAProblem
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boolean isUnrecognizedPropertyNamesConsideredAProblem()
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    If true, an unrecognized name is considered a problem that will stop application startup. This is a safety feature because a unrecognized property name in a properties file could be a typo. For other property sources, however, like System.properties, there are many non-AndHow related values that are expected to be present, so this rule cannot be enforced.
    
    Returns:
  - getConfigSamplePrinter
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SamplePrinter getConfigSamplePrinter()
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    Returns a ConfigSamplePrinter, which can be used to print a configuration sample for this Loader. This method may return null if there is no sample printer for this loader.
    
    Returns:
  - getLoaderType
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String getLoaderType()
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    The type of the loader, such as JNDI, PropertyFile, SystemProperty, etc.. The actual return value is arbitrary, but should be consistent between loaders of the same type. The values returned by getLoaderType and getLoaderDialect are used to removed duplicate loader types when printing sample files. If two loader instances are of the same type and dialect, only one will print the sample file.
    
    Returns:
    
    Must never returns null.
  - getLoaderDialect
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String getLoaderDialect()
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    The type dialect of the loader. For property files, this might be either KeyValuePair or xml for example. The actual return value is arbitrary, but should be consistent between loaders of the same type and dialect. The values returned by getLoaderType and getLoaderDialect are used to removed duplicate loader types when printing sample files. If two loader instances are of the same type and dialect, only one will print the sample file.
    
    Returns:
    
    May return null if there is no meaningful dialect for this type.

Interface Loader

Method Summary

Method Detail

load

getClassConfig

getInstanceConfig

getSpecificLoadDescription

isTrimmingRequiredForStringValues

isUnrecognizedPropertyNamesConsideredAProblem

getConfigSamplePrinter

getLoaderType

getLoaderDialect