public abstract class AbstractConverter extends java.lang.Object implements Converter
Converter
implementation that provides the structure
for handling conversion to and from a specified type.
This implementation provides the basic structure for
converting to/from a specified type optionally using a default
value or throwing a ConversionException
if a
conversion error occurs.
Implementations should provide conversion to the specified
type and from the specified type to a String
value
by implementing the following methods:
convertToString(value)
- convert to a String
(default implementation uses the objects toString()
method).convertToType(Class, value)
- convert
to the specified typeConstructor and Description |
---|
AbstractConverter()
Construct a Converter that throws a
ConversionException if an error occurs. |
AbstractConverter(java.lang.Object defaultValue)
Construct a Converter that returns a default
value if an error occurs.
|
Modifier and Type | Method and Description |
---|---|
java.lang.Object |
convert(java.lang.Class type,
java.lang.Object value)
Convert the input object into an output object of the
specified type.
|
protected java.lang.Object |
convertArray(java.lang.Object value)
Return the first element from an Array (or Collection)
or the value unchanged if not an Array (or Collection).
|
protected java.lang.String |
convertToString(java.lang.Object value)
Convert the input object into a String.
|
protected abstract java.lang.Object |
convertToType(java.lang.Class type,
java.lang.Object value)
Convert the input object into an output object of the
specified type.
|
protected java.lang.Object |
getDefault(java.lang.Class type)
Return the default value for conversions to the specified
type.
|
protected abstract java.lang.Class |
getDefaultType()
Return the default type this
Converter handles. |
protected java.lang.Object |
handleError(java.lang.Class type,
java.lang.Object value,
java.lang.Throwable cause)
Handle Conversion Errors.
|
protected java.lang.Object |
handleMissing(java.lang.Class type)
Handle missing values.
|
boolean |
isUseDefault()
Indicates whether a default value will be returned or exception
thrown in the event of a conversion error.
|
protected void |
setDefaultValue(java.lang.Object defaultValue)
Set the default value, converting as required.
|
java.lang.String |
toString()
Provide a String representation of this converter.
|
public AbstractConverter()
ConversionException
if an error occurs.public AbstractConverter(java.lang.Object defaultValue)
defaultValue
- The default value to be returned
if the value to be converted is missing or an error
occurs converting the value.public boolean isUseDefault()
true
if a default value will be returned for
conversion errors or false
if a ConversionException
will be thrown.public java.lang.Object convert(java.lang.Class type, java.lang.Object value)
convert
in interface Converter
type
- Data type to which this value should be convertedvalue
- The input value to be convertedConversionException
- if conversion cannot be performed
successfully and no default is specified.protected java.lang.String convertToString(java.lang.Object value) throws java.lang.Throwable
N.B.This implementation simply uses the value's
toString()
method and should be overriden if a
more sophisticated mechanism for conversion to a String
is required.
value
- The input value to be converted.java.lang.Throwable
- if an error occurs converting to a Stringprotected abstract java.lang.Object convertToType(java.lang.Class type, java.lang.Object value) throws java.lang.Throwable
Typical implementations will provide a minimum of
String --> type
conversion.
type
- Data type to which this value should be converted.value
- The input value to be converted.java.lang.Throwable
- if an error occurs converting to the specified typeprotected java.lang.Object convertArray(java.lang.Object value)
value
- The value to convertprotected java.lang.Object handleError(java.lang.Class type, java.lang.Object value, java.lang.Throwable cause)
If a default value has been specified then it is returned otherwise a ConversionException is thrown.
type
- Data type to which this value should be converted.value
- The input value to be convertedcause
- The exception thrown by the convert
methodConversionException
- if no default value has been
specified for this Converter
.protected java.lang.Object handleMissing(java.lang.Class type)
If a default value has been specified then it is returned otherwise a ConversionException is thrown.
type
- Data type to which this value should be converted.ConversionException
- if no default value has been
specified for this Converter
.protected void setDefaultValue(java.lang.Object defaultValue)
If the default value is different from the type the
Converter
handles, it will be converted
to the handled type.
defaultValue
- The default value to be returned
if the value to be converted is missing or an error
occurs converting the value.ConversionException
- if an error occurs converting
the default valueprotected abstract java.lang.Class getDefaultType()
Converter
handles.Converter
handles.protected java.lang.Object getDefault(java.lang.Class type)
type
- Data type to which this value should be converted.public java.lang.String toString()
toString
in class java.lang.Object
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