NumberTransformerBase (JGUIraffe BOM 1.3.1 API)

java.lang.Object
- net.sf.jguiraffe.transform.NumberTransformerBase<T>

Type Parameters:: T - the type handled by this transformer

All Implemented Interfaces:: Transformer, Validator

Direct Known Subclasses:: AbstractDecimalTransformer, AbstractIntegerTransformer

public abstract class NumberTransformerBase<T extends Number>
extends Object
implements Transformer, Validator

An abstract base class for transformers and validators for numbers.

This base class already provides the major part of functionality for validating numeric input and transforming strings to number objects. Concrete sub classes are responsible for the creation of a java.text.NumberFormat object that is used for parsing the user input. The class also supports certain semantic checks, especially whether an entered number lies in a specified interval.

This class makes use of Java generics to be independent on a concrete number type. The returned (transformed) object will be of this type, and also the specified minimum or maximum values must use this type.

The following properties are supported by this class:

Property	Description	Default
minimum	Here the minimum value can be defined. Entered numbers are checked to be greater or equal than this number. If this property is undefined, no minimum checks will be performed.	undefined
maximum	Here the maximum value can be defined. Entered numbers are checked to be less or equal than this number. If this property is undefined, no maximum checks will be performed.	undefined

Validation of user input can fail for multiple reasons. The following table lists the possible error messages:

Message key	Description	Parameters
	The passed in string cannot be parsed to a number object.	{0} = the input string
	The entered number is too small. This error message is returned if the number is less than the specified minimum number and no maximum number was specified. (If both a minimum and a maximum number are specified, the error code is used.)	{0} = the minimum number
	The entered number is too big. This error message is returned if the number is greater than the specified maximum number and no minimum number was specified. (If both a minimum and a maximum number are specified, the error code is used.)	{0} = the maximum number
	The entered number is not in the interval spanned by the minimum and the maximum value. If both a minimum and a maximum are specified and the entered number does not meet these constraints, this error message is produced rather than one of or .	{0} = the minimum value, {1} = the maximum value

The class implements both the Transformer and Validator interfaces. It is safe to use an instance concurrently as transformer and validator for the same or multiple input fields.

Version:: $Id: NumberTransformerBase.java 205 2012-01-29 18:29:57Z oheger $
Author:: Oliver Heger

Field Summary

Fields
Modifier and Type	Field and Description
`protected static String`	`PROP_MAXIMUM` Constant for the maximum property.
`protected static String`	`PROP_MINIMUM` Constant for the minimum property.

Constructor Summary

Constructors
Constructor and Description

NumberTransformerBase()

Constructors
Constructor and Description
`NumberTransformerBase()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected abstract T`	`convert(Number n)` Converts the specified number to the target type supported by this transformer.
`protected abstract NumberFormat`	`createFormat(Locale locale)` Creates the format object for parsing a number.
`protected ValidationResult`	`errorResult(String errorKey, TransformerContext ctx, Object... params)` Creates a validation result if an error occurred.
`protected abstract T`	`fetchProperty(org.apache.commons.configuration.Configuration config, String property, T defaultValue)` Fetches a property of the supported type from the specified configuration object.
`T`	`getMaximum()` Returns the maximum value.
`T`	`getMinimum()` Returns the minimum value.
`protected ValidationResult`	`isNumberValid(T n, NumberFormat fmt, TransformerContext ctx, T min, T max)` Validates an entered number.
`ValidationResult`	`isValid(Object o, TransformerContext ctx)` Validates the specified object.
`void`	`setMaximum(T maximum)` Sets the maximum value.
`void`	`setMinimum(T minimum)` Sets the minimum value.
`Object`	`transform(Object o, TransformerContext ctx)` Transforms the specified object to the target format.
`protected T`	`transformToNumber(Object o, TransformerContext ctx, NumberFormat fmt)` Transforms the given object into a number.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - PROP_MINIMUM
```
protected static final String PROP_MINIMUM
```
    Constant for the minimum property.
    
    See Also:
    
    Constant Field Values
  - PROP_MAXIMUM
```
protected static final String PROP_MAXIMUM
```
    Constant for the maximum property.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - NumberTransformerBase
```
public NumberTransformerBase()
```
- Method Detail
  - getMinimum
```
public T getMinimum()
```
    Returns the minimum value.
    
    Returns:
    
    the minimum value (can be null)
  - setMinimum
```
public void setMinimum(T minimum)
```
    Sets the minimum value. If a minimum value is specified, the validator implementation will check whether an entered number is not less than this minimum value.
    
    Parameters:
    
    minimum - the minimum value
  - getMaximum
```
public T getMaximum()
```
    Returns the maximum value.
    
    Returns:
    
    the maximum value (can be null)
  - setMaximum
```
public void setMaximum(T maximum)
```
    Sets the maximum value. If a maximum value is specified, the validator implementation will check whether an entered number is not greater than this maximum value.
    
    Parameters:
    
    maximum - the maximum value
  - transform
```
public Object transform(Object o,
                        TransformerContext ctx)
                 throws Exception
```
    Transforms the specified object to the target format. This implementation tries to convert the passed in object to a Number of the type specified by the generics parameter for this class. This is done by using a java.text.NumberFormat object. If the passed in object is null, null will also be returned.
    
    Specified by:
    
    transform in interface Transformer
    
    Parameters:
    
    o - the object to be transformed
    
    ctx - the transformer context
    
    Returns:
    
    the transformed object
    
    Throws:
    
    Exception - if conversion fails
  - isValid
```
public ValidationResult isValid(Object o,
                                TransformerContext ctx)
```
    Validates the specified object. This implementation checks whether the object can be transformed to a number. If this is the case, isNumberValid() will be called to check whether the number lies in a valid range. Depending on these checks a validation result object is returned. A null object or an empty string are considered valid.
    
    Specified by:
    
    isValid in interface Validator
    
    Parameters:
    
    o - the object to be validated
    
    ctx - the transformer context
    
    Returns:
    
    an object with the results of the validation
  - transformToNumber
```
protected T transformToNumber(Object o,
                              TransformerContext ctx,
                              NumberFormat fmt)
                       throws ParseException
```
    Transforms the given object into a number. This method is called by both transform() and isValid(). It performs the actual transformation. The passed in object may be null or empty, in which case null is returned.
    
    Parameters:
    
    o - the object to be transformed
    
    ctx - the transformer context
    
    fmt - the format object to be used
    
    Returns:
    
    the converted number
    
    Throws:
    
    ParseException - if transformation fails
  - isNumberValid
```
protected ValidationResult isNumberValid(T n,
                                         NumberFormat fmt,
                                         TransformerContext ctx,
                                         T min,
                                         T max)
```
    Validates an entered number. This method is called by isValid() if the passed in object can be successfully converted into a number. It checks this number against the minimum and maximum values (if defined).
    
    Parameters:
    
    n - the number to check
    
    fmt - the format object (used for formatting the minimum and/or maximum values in error messages)
    
    ctx - the transformation context
    
    min - the minimum value (can be null)
    
    max - the maximum value (can be null)
    
    Returns:
    
    an object with the results of the validation
  - errorResult
```
protected ValidationResult errorResult(String errorKey,
                                       TransformerContext ctx,
                                       Object... params)
```
    Creates a validation result if an error occurred.
    
    Parameters:
    
    errorKey - the key of the error message
    
    ctx - the transformer context
    
    params - optional parameters for the error message
    
    Returns:
    
    the validation result with this error
  - convert
```
protected abstract T convert(Number n)
```
    Converts the specified number to the target type supported by this transformer. This method is called after the object to be transformed was parsed by a NumberFormat object. There is no guarantee that the result of this parsing process matches the desired type. If this is not the case, this method will be called.
    
    Parameters:
    
    n - the number to be converted
    
    Returns:
    
    the converted number
    
    Throws:
    
    IllegalArgumentException - if the number cannot be converted to the target type (e.g. because it does not fit into the supported range)
  - createFormat
```
protected abstract NumberFormat createFormat(Locale locale)
```
    Creates the format object for parsing a number. This method is called whenever a string (entered by the user) has to be converted into a number.
    
    Parameters:
    
    locale - the locale to use
    
    Returns:
    
    the format object for parsing the number
  - fetchProperty
```
protected abstract T fetchProperty(org.apache.commons.configuration.Configuration config,
                                   String property,
                                   T defaultValue)
```
    Fetches a property of the supported type from the specified configuration object. This method is called for determining the current values of type-related properties (e.g. the minimum and maximum values). An implementation has to invoke the appropriate methods on the passed in Configuration object.
    
    Parameters:
    
    config - the configuration object
    
    property - the name of the property to be obtained
    
    defaultValue - the default value for this property
    
    Returns:
    
    the value of this property

Class NumberTransformerBase<T extends Number>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

PROP_MINIMUM

PROP_MAXIMUM

Constructor Detail

NumberTransformerBase

Method Detail

getMinimum

setMinimum

getMaximum

setMaximum

transform

isValid

transformToNumber

isNumberValid

errorResult

convert

createFormat

fetchProperty