com.opensymphony.xwork2.conversion.impl

Class XWorkConverter

java.lang.Object

com.opensymphony.xwork2.conversion.impl.DefaultTypeConverter

com.opensymphony.xwork2.conversion.impl.XWorkConverter

All Implemented Interfaces:

TypeConverter

public class XWorkConverter
extends DefaultTypeConverter

XWorkConverter is a singleton used by many of the Struts 2's Ognl extension points, such as InstantiatingNullHandler, XWorkListPropertyAccessor etc to do object conversion.

Type conversion is great for situations where you need to turn a String in to a more complex object. Because the web is type-agnostic (everything is a string in HTTP), Struts 2's type conversion features are very useful. For instance, if you were prompting a user to enter in coordinates in the form of a string (such as "3, 22"), you could have Struts 2 do the conversion both from String to Point and from Point to String.

Using this "point" example, if your action (or another compound object in which you are setting properties on) has a corresponding ClassName-conversion.properties file, Struts 2 will use the configured type converters for conversion to and from strings. So turning "3, 22" in to new Point(3, 22) is done by merely adding the following entry to ClassName-conversion.properties (Note that the PointConverter should impl the TypeConverter interface):

point = com.acme.PointConverter

Your type converter should be sure to check what class type it is being requested to convert. Because it is used for both to and from strings, you will need to split the conversion method in to two parts: one that turns Strings in to Points, and one that turns Points in to Strings.

After this is done, you can now reference your point (using <s:property value="point"/> in JSP or ${point} in FreeMarker) and it will be printed as "3, 22" again. As such, if you submit this back to an action, it will be converted back to a Point once again.

In some situations you may wish to apply a type converter globally. This can be done by editing the file xwork-conversion.properties in the root of your class path (typically WEB-INF/classes) and providing a property in the form of the class name of the object you wish to convert on the left hand side and the class name of the type converter on the right hand side. For example, providing a type converter for all Point objects would mean adding the following entry:

com.acme.Point = com.acme.PointConverter

Type conversion should not be used as a substitute for i18n. It is not recommended to use this feature to print out properly formatted dates. Rather, you should use the i18n features of Struts 2 (and consult the JavaDocs for JDK's MessageFormat object) to see how a properly formatted date should be displayed.

Any error that occurs during type conversion may or may not wish to be reported. For example, reporting that the input "abc" could not be converted to a number might be important. On the other hand, reporting that an empty string, "", cannot be converted to a number might not be important - especially in a web environment where it is hard to distinguish between a user not entering a value vs. entering a blank value.

By default, all conversion errors are reported using the generic i18n key xwork.default.invalid.fieldvalue, which you can override (the default text is Invalid field value for field "xxx", where xxx is the field name) in your global i18n resource bundle.

However, sometimes you may wish to override this message on a per-field basis. You can do this by adding an i18n key associated with just your action (Action.properties) using the pattern invalid.fieldvalue.xxx, where xxx is the field name.

It is important to know that none of these errors are actually reported directly. Rather, they are added to a map called conversionErrors in the ActionContext. There are several ways this map can then be accessed and the errors can be reported accordingly.

Version:

$Date$ $Id$

Author:

Pat Lightbody, Rainer Hermanns, Alexandru Popescu, tm_jee

See Also:

XWorkBasicConverter

Field Summary

Fields

Modifier and Type	Field and Description
static String	CONVERSION_COLLECTION_PREFIX
static String	CONVERSION_ERROR_PROPERTY_PREFIX
static String	CONVERSION_PROPERTY_FULLNAME
static String	LAST_BEAN_CLASS_ACCESSED
static String	LAST_BEAN_PROPERTY_ACCESSED
static String	MESSAGE_INDEX_BRACKET_PATTERN
static String	MESSAGE_INDEX_PATTERN
static Pattern	messageIndexPattern
static String	PERIOD
static String	REPORT_CONVERSION_ERRORS

Fields inherited from class com.opensymphony.xwork2.conversion.impl.DefaultTypeConverter

MILLISECOND_FORMAT

Fields inherited from interface com.opensymphony.xwork2.conversion.TypeConverter

NO_CONVERSION_POSSIBLE, TYPE_CONVERTER_CONTEXT_KEY

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	XWorkConverter()

Method Summary

Modifier and Type	Method and Description
protected void	addConverterMapping(Map<String,Object> mapping, Class clazz) Looks for converter mappings for the specified class and adds it to an existing map.
String	buildConverterFilename(Class clazz)
protected Map<String,Object>	buildConverterMapping(Class clazz) Looks for converter mappings for the specified class, traversing up its class hierarchy and interfaces and adding any additional mappings it may find.
Object	convertValue(Map<String,Object> map, Object o, Class aClass)
Object	convertValue(Map<String,Object> context, Object target, Member member, String property, Object value, Class toClass) Convert value from one form to another.
static String	getConversionErrorMessage(String propertyName, Class toClass, ValueStack stack)
protected Object	getConverter(Class clazz, String property)
protected void	handleConversionException(Map<String,Object> context, String property, Object value, Object object, Class toClass)
TypeConverter	lookup(Class clazz) Looks for a TypeConverter in the default mappings.
TypeConverter	lookup(String className, boolean isPrimitive) Looks for a TypeConverter in the default mappings.
void	registerConverter(String className, TypeConverter converter)
void	registerConverterNotFound(String className)
void	setConversionAnnotationProcessor(ConversionAnnotationProcessor annotationProcessor)
void	setConversionFileProcessor(ConversionFileProcessor fileProcessor)
void	setDefaultTypeConverter(XWorkBasicConverter converter)
void	setFileManagerFactory(FileManagerFactory fileManagerFactory)
void	setReloadingConfigs(String reloadingConfigs)
void	setTypeConverterHolder(TypeConverterHolder converterHolder)

Methods inherited from class com.opensymphony.xwork2.conversion.impl.DefaultTypeConverter

bigDecValue, bigIntValue, booleanValue, convertValue, doubleValue, enumValue, getLocale, getTypeConverter, longValue, setContainer, stringValue, stringValue

Methods inherited from class java.lang.Object

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

Field Detail

REPORT_CONVERSION_ERRORS

public static final String REPORT_CONVERSION_ERRORS

See Also:

Constant Field Values

CONVERSION_PROPERTY_FULLNAME

public static final String CONVERSION_PROPERTY_FULLNAME

See Also:

Constant Field Values

CONVERSION_ERROR_PROPERTY_PREFIX

public static final String CONVERSION_ERROR_PROPERTY_PREFIX

See Also:

Constant Field Values

CONVERSION_COLLECTION_PREFIX

public static final String CONVERSION_COLLECTION_PREFIX

See Also:

Constant Field Values

LAST_BEAN_CLASS_ACCESSED

public static final String LAST_BEAN_CLASS_ACCESSED

See Also:

Constant Field Values

LAST_BEAN_PROPERTY_ACCESSED

public static final String LAST_BEAN_PROPERTY_ACCESSED

See Also:

Constant Field Values

MESSAGE_INDEX_PATTERN

public static final String MESSAGE_INDEX_PATTERN

See Also:

Constant Field Values

MESSAGE_INDEX_BRACKET_PATTERN

public static final String MESSAGE_INDEX_BRACKET_PATTERN

See Also:

Constant Field Values

PERIOD

public static final String PERIOD

See Also:

Constant Field Values

messageIndexPattern

public static final Pattern messageIndexPattern

Constructor Detail

XWorkConverter

protected XWorkConverter()

Method Detail

setDefaultTypeConverter

public void setDefaultTypeConverter(XWorkBasicConverter converter)

setFileManagerFactory

public void setFileManagerFactory(FileManagerFactory fileManagerFactory)

setReloadingConfigs

public void setReloadingConfigs(String reloadingConfigs)

setConversionFileProcessor

public void setConversionFileProcessor(ConversionFileProcessor fileProcessor)

setConversionAnnotationProcessor

public void setConversionAnnotationProcessor(ConversionAnnotationProcessor annotationProcessor)

setTypeConverterHolder

public void setTypeConverterHolder(TypeConverterHolder converterHolder)

getConversionErrorMessage

public static String getConversionErrorMessage(String propertyName,
                                               Class toClass,
                                               ValueStack stack)

buildConverterFilename

public String buildConverterFilename(Class clazz)

convertValue

public Object convertValue(Map<String,Object> map,
                           Object o,
                           Class aClass)

Overrides:

convertValue in class DefaultTypeConverter

convertValue

public Object convertValue(Map<String,Object> context,
                           Object target,
                           Member member,
                           String property,
                           Object value,
                           Class toClass)

Convert value from one form to another. Minimum requirement of arguments:

• supplying context, toClass and value
• supplying context, target and value.

Specified by:

convertValue in interface TypeConverter

Overrides:

convertValue in class DefaultTypeConverter

Parameters:

context - context under which the conversion is being done

target - target object in which the property is being set

member - member (Constructor, Method or Field) being set

property - property name being set

value - value to be converted

toClass - type to which value is converted

Returns:

Converted value of type toType or TypeConverter.NoConversionPossible to indicate that the conversion was not possible.

See Also:

TypeConverter.convertValue(java.util.Map, java.lang.Object, java.lang.reflect.Member, java.lang.String, java.lang.Object, java.lang.Class)

lookup

public TypeConverter lookup(String className,
                            boolean isPrimitive)

Looks for a TypeConverter in the default mappings.

Parameters:

className - name of the class the TypeConverter must handle

isPrimitive - is primitive?

Returns:

a TypeConverter to handle the specified class or null if none can be found

lookup

public TypeConverter lookup(Class clazz)

Looks for a TypeConverter in the default mappings.

Parameters:

clazz - the class the TypeConverter must handle

Returns:

a TypeConverter to handle the specified class or null if none can be found

getConverter

protected Object getConverter(Class clazz,
                              String property)

handleConversionException

protected void handleConversionException(Map<String,Object> context,
                                         String property,
                                         Object value,
                                         Object object,
                                         Class toClass)

registerConverter

public void registerConverter(String className,
                              TypeConverter converter)

registerConverterNotFound

public void registerConverterNotFound(String className)

addConverterMapping

protected void addConverterMapping(Map<String,Object> mapping,
                                   Class clazz)

Looks for converter mappings for the specified class and adds it to an existing map. Only new converters are added. If a converter is defined on a key that already exists, the converter is ignored.

Parameters:

mapping - an existing map to add new converter mappings to

clazz - class to look for converter mappings for

buildConverterMapping

protected Map<String,Object> buildConverterMapping(Class clazz)
                                            throws Exception

Looks for converter mappings for the specified class, traversing up its class hierarchy and interfaces and adding any additional mappings it may find. Mappings lower in the hierarchy have priority over those higher in the hierarchy.

Parameters:

clazz - the class to look for converter mappings for

Returns:

the converter mappings

Throws:

Exception - in case of any errors