You don't need your own describe method anymore. BeanUtils has added the
capability to register conversion methods, to go from String to any
arbitrary object. So for example, I have a MSCalendar object whose
toString puts out mm/dd/yyyy format, and can take that same format in a
constructor.
The MSConverter (attached) is mostly copied from one of Craig's
converters in the Commons BeanUtils package.
public void testStuff()
{
Map map = null;
int i;
// Register converters that enable conversion of String properties
// to a designated class. String->MSCalendar
ConvertUtils.register(new MSCalendarConverter(),
MSCalendar.class);
EmployeeBean emp = new EmployeeBean();
emp.setFirstName("Joe");
emp.setLastName("Klein");
emp.setBirthDate(new MSCalendar("1/1/1999"));
EmployeeFormBean form = new EmployeeFormBean();
try {
// Copy all properties of an EmployeeBean to the corresponding
// properties of an EmployeeFormBean.
// This process uses the toString() method of each
// property in EmployeeBean as the value to put into
// the corresponding String property in the form.
map = BeanUtils.describe(emp);
BeanUtils.populate(form, map);
// Conversely, copy all the properties from the form into
// the corresponding properties of EmployeeBean, converting
// from String to the taget object type.
emp = new EmployeeBean();
map = BeanUtils.describe(form);
BeanUtils.populate(emp, map);
} catch(Exception ex) {
fail("failure:"+ex.getStackTrace());
}
}
}
DHS Struts wrote:
> I was wondering if anyone had a custom describe method they would be
> willing to share as an example of what Ted Husted describes in his
> "Struts Catalog" in the 'Use a "populate" utility to exchange data with
> value objects' section?
>
> I understand the basic concept of needing to write my own describe() for
> those beans that have Date attributes (because the BeanUtil.populate()
> can't handle them), but I am not having much luck getting it to work.
>
> If you have some code and are willing to share I would appreciate it.
> Also, if you would like to see what I have attempted I can post that
> here as well.
>
> Thank you in advance,
>
> mark n.
>
> _________________________________________________________________
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package edu.umich.umms.beanutils;
import java.sql.Date;
import org.apache.commons.beanutils.ConversionException;
import org.apache.commons.beanutils.Converter;
/**
* <p>Standard {@link Converter} implementation that converts an incoming
* String into a <code>edu.umich.umms.util.MSCalendar</code> object, optionally using a
* default value or throwing a {@link ConversionException} if a conversion
* error occurs.</p>
*
*/
public final class MSCalendarConverter implements Converter {
// ----------------------------------------------------------- Constructors
/**
* Create a {@link Converter} that will throw a {@link ConversionException}
* if a conversion error occurs.
*/
public MSCalendarConverter() {
this(null);
}
/**
* Create a {@link Converter} that will return the specified default value
* if a conversion error occurs.
*
* @param defaultValue The default value to be returned
*/
public MSCalendarConverter(Object defaultValue) {
this.defaultValue = defaultValue;
}
// ----------------------------------------------------- Instance Variables
/**
* The default value specified to our Constructor, if any.
*/
private Object defaultValue = null;
// --------------------------------------------------------- Public Methods
/**
* Convert the specified input object into an output object of the
* specified type.
*
* @param type Data type to which this value should be converted
* @param value The input value to be converted
*
* @exception ConversionException if conversion cannot be performed
* successfully
*/
public Object convert(Class type, Object value) {
if (value == null) {
if (defaultValue != null) {
return (defaultValue);
} else {
throw new ConversionException("No value specified");
}
}
try {
return new edu.umich.umms.util.MSCalendar((String) value);
// return (Date.valueOf((String) value));
} catch (Exception e) {
if (defaultValue != null) {
return (defaultValue);
} else {
throw new ConversionException(e);
}
}
}
}
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