Is it possible to globally configure the default comparators used for 'auto'? [closed]

answered 2013-02-05 10:18:28 +0800

RetoH
44 ● 5

Thanks to samchuang's hints I was able to roll my own workaround. Here my (hackish) solution.

Note that I plan to extend this for property "paths" (e.g. "bean.property1.property2"), but at the moment it only works for simple "one-level" properties. Also note that the current version cannot handle null-entities or null-properties.

I defined a language addon (as suggested by samchuang):

<language-addon>

<addon-name>MyColumn</addon-name>
  <language-name>xul/html</language-name>

  <component>
    <component-name>column</component-name>
    <extends>column</extends>
    <component-class>mypackage.MyColumn</component-class>
  </component>

</language-addon>

The implementation of MyColumn:

public class MyColumn extends Column
{
  @SuppressWarnings("unused")
  private static final Logger LOGGER = Logger.getLogger(IbrLimsColumn.class.getName());

  public MyColumn()
  {
  }

  @Override
  public void setSort(String type) throws ClassNotFoundException, InstantiationException, IllegalAccessException
  {
    if(type.startsWith("str"))
    {
      String propertyName = type.substring("str(".length(), type.length() - 1);

      setSortAscending(new StringPropertyComparator(propertyName, true));
      setSortDescending(new StringPropertyComparator(propertyName, false));
    }
    else
    {
      super.setSort(type);
    }
  }
}

The usage:

<grid model="@load(vm.employees)" sizedByContent="true">
  <columns sizable="true" menupopup="auto">
    <column label="Last name" sort="str(lastName)" />
    <column label="First name" sort="str(firstName)" />
  </columns>
  <template name="model">
    <row>
      <a href="/Employee.zul?id=${each.id}">${each.lastName}</a>
      <label value="${each.firstName}" />         
    </row>
  </template>
</grid>

And finally the heart of the implementation, the StringPropertyComparator:

public class StringPropertyComparator implements Comparator<Object>
{
  private final boolean       m_ascending;
  private final String        m_propertyPath;   
  private Method              m_getter     = null;
  private Comparator          m_comparator = null;

  public StringPropertyComparator(String propertyPath, boolean ascending)
  {
    m_propertyPath = propertyPath;
    m_ascending = ascending;
  }

  @Override
  public int compare(Object entity1, Object entity2)
  {
    try
    {
      return compare0(entity1, entity2);
    }
    catch(Throwable t)
    {
      throw new RuntimeException("unexpected", t);
    }
  }

  private int compare0(Object entity1, Object entity2) throws Exception
  {
    if(m_getter == null)
    {
      m_getter = ReflectionTools.getGetterMethod(entity1, m_propertyPath);
    }

    if(m_comparator == null)
    {
      // determine comparator based on property type

      Collator collator = Collator.getInstance(new Locale("en", "US"));
      // sort A, a, Ä, ä, Â, â, À, à (and other accents) at the same position in the list
      collator.setStrength(Collator.PRIMARY);

      m_comparator = collator;
    }

    Object value1 = m_getter.invoke(entity1);
    Object value2 = m_getter.invoke(entity2);

    if(m_ascending)
    {
      return m_comparator.compare(value1, value2);
    }
    else
    {
      return -m_comparator.compare(value1, value2);
    }
  }
}

And the ReflectionTools:

public class ReflectionTools
{
  public static Method getGetterMethod(Object bean, String propertyName)
  {
    Class<?> beanClass = bean.getClass();

    try
    {
      return beanClass.getMethod(getGetterName(propertyName));
    }
    catch(Throwable t)
    {
      // ignore
    }

    try
    {
      return beanClass.getMethod(getBooleanGetterName(propertyName));
    }
    catch(Throwable t)
    {
      // ignore
    }

    throw new IllegalArgumentException("not getter method found for '" + propertyName + "', bean: " + bean);
  }

  public static String getGetterName(String propertyName)
  {
    String getterName = "get" + capitalizeFirstLetter(propertyName);
    return getterName;
  }

  public static String getBooleanGetterName(String propertyName)
  {
    String getterName = "is" + capitalizeFirstLetter(propertyName);
    return getterName;
  }

  private static String capitalizeFirstLetter(String string)
  {
    String result = string.substring(0, 1).toUpperCase() + string.substring(1, string.length());
    return result;
  }
}