Converter (Java EE 5 SDK)

javax.faces.convert Interface Converter

所有已知实现子孙类:

BigDecimalConverter, BigIntegerConverter, BooleanConverter, ByteConverter, CharacterConverter, DateTimeConverter, DoubleConverter, EnumConverter, FloatConverter, IntegerConverter, LongConverter, NumberConverter, ShortConverter

public interface Converter

Converter is an interface describing a Java class that can perform Object-to-String and String-to-Object conversions between model data objects and a String representation of those objects that is suitable for rendering.

Converter implementations must have a zero-arguments public constructor. In addition, if the Converter class wishes to have configuration property values saved and restored with the component tree, the implementation must also implement StateHolder.

Starting with version 1.2 of the specification, an exception to the above zero-arguments constructor requirement has been introduced. If a converter has a single argument constructor that takes a Class instance and the Class of the data to be converted is known at converter instantiation time, this constructor must be used to instantiate the converter instead of the zero-argument version. This enables the per-class conversion of Java enumerated types.

If any Converter implementation requires a java.util.Locale to perform its job, it must obtain that Locale from the UIViewRoot of the current FacesContext, unless the Converter maintains its own Locale as part of its state.

getAsObject

Object getAsObject(FacesContext context,
                   UIComponent component,
                   String value)

Convert the specified string value, which is associated with the specified UIComponent, into a model data object that is appropriate for being stored during the Apply Request Values phase of the request processing lifecycle.

参数:

context - FacesContext for the request being processed

component - UIComponent with which this model object value is associated

value - String value to be converted (may be null)

返回:

null if the value to convert is null, otherwise the result of the conversion

抛出异常:

ConverterException - if conversion cannot be successfully performed

NullPointerException - if context or component is null

getAsString

String getAsString(FacesContext context,
                   UIComponent component,
                   Object value)

Convert the specified model object value, which is associated with the specified UIComponent, into a String that is suitable for being included in the response generated during the Render Response phase of the request processing lifeycle.

参数:

context - FacesContext for the request being processed

component - UIComponent with which this model object value is associated

value - Model object value to be converted (may be null)

返回:

a zero-length String if value is null, otherwise the result of the conversion

抛出异常:

ConverterException - if conversion cannot be successfully performed

NullPointerException - if context or component is null

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