Posted on 2008-01-14 08:59
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Java插件開發(fā)
這一節(jié)主要介紹如何給編輯器增加屬性頁，屬性頁主要用來顯示編輯器中選中對(duì)象的屬性的，比如在編輯器選中活動(dòng)，可以在屬性頁上顯示活動(dòng)的大小和位置等信息，要實(shí)現(xiàn)這一功能，首先要讓模型實(shí)現(xiàn)IPropertySource接口，我們讓模型的基類ModelElement實(shí)現(xiàn)這個(gè)接口，基類要實(shí)現(xiàn)這接口中六個(gè)方法，這六個(gè)方法如下：
/** *//** An empty property descriptor. */
private static final IPropertyDescriptor[] EMPTY_ARRAY = new IPropertyDescriptor[0];
/** *//**
* Returns a value for this property source that can be edited in a property sheet.
* @return this instance
*/
public Object getEditableValue() 
{
return this;
}
/** *//**
* Children should override this. The default implementation returns an empty array.
*/
public IPropertyDescriptor[] getPropertyDescriptors() {
return EMPTY_ARRAY;
}
/** *//**
* Children should override this. The default implementation returns null.
*/
public Object getPropertyValue(Object id) {
// TODO Auto-generated method stub
return null;
}
/** *//**
* Children should override this. The default implementation returns false.
*/
public boolean isPropertySet(Object id) {
// TODO Auto-generated method stub
return false;
}
/** *//**
* Children should override this. The default implementation does nothing.
*/
public void resetPropertyValue(Object id) {
// TODO Auto-generated method stub
}
/** *//**
* Children should override this. The default implementation does nothing.
*/
public void setPropertyValue(Object id, Object value) {
// TODO Auto-generated method stub
}這六個(gè)方法的含義在JavaDoc中已經(jīng)說的很清楚了，在這個(gè)類中我們還定義了IPropertyDescriptor類型的數(shù)組，這個(gè)數(shù)組的作用是存放要顯示屬性的名稱，由于根模型沒有什么可顯示的屬性，所以為空。當(dāng)我們?cè)诰庉嬈髦羞x中活動(dòng)時(shí)，在屬性頁上要顯示它的屬性，因此我們應(yīng)該在AbstractActivity類中覆蓋父類中相應(yīng)的方法，代碼如下：
/** *//**
* 活動(dòng)要顯示屬性的名稱
* There is one IPropertyDescriptor entry per editable property.
* @see #getPropertyDescriptors()
* @see #getPropertyValue(Object)
* @see #setPropertyValue(Object, Object)
*/
private static IPropertyDescriptor[] descriptors;
/**//*
* Initializes the property descriptors array.
* @see #getPropertyDescriptors()
* @see #getPropertyValue(Object)
* @see #setPropertyValue(Object, Object)
*/
static {
descriptors = new IPropertyDescriptor[] {
new TextPropertyDescriptor(XPOS_PROP, "X"), // id and
description pair
new TextPropertyDescriptor(YPOS_PROP, "Y"),
new TextPropertyDescriptor(WIDTH_PROP, "Width"),
new TextPropertyDescriptor(HEIGHT_PROP, "Height")
};
// use a custom cell editor validator for all four array entries
for (int i = 0; i < descriptors.length; i++) {
((PropertyDescriptor) descriptors[i]).setValidator(new
ICellEditorValidator() {
public String isValid(Object value) {
int intValue = -1;
try {
intValue = Integer.parseInt((String)
value);
} catch (NumberFormatException exc) {
return "Not a number";
}
return (intValue >= 0) ? null : "Value must be >=
0";
}
});
}
} // static
/** *//**
* Returns an array of IPropertyDescriptors for this AbstractActivity.
* <p>The returned array is used to fill the property view, when the edit-part
corresponding
* to this model element is selected.</p>
* @see #descriptors
* @see #getPropertyValue(Object)
* @see #setPropertyValue(Object, Object)
*/
public IPropertyDescriptor[] getPropertyDescriptors() {
return descriptors;
}
/** *//**
* Return the property value for the given propertyId, or null.
* <p>The property view uses the IDs from the IPropertyDescriptors array
* to obtain the value of the corresponding properties.</p>
* @see #descriptors
* @see #getPropertyDescriptors()
*/
public Object getPropertyValue(Object propertyId) {
if (XPOS_PROP.equals(propertyId)) {
return Integer.toString(location.x);
}
if (YPOS_PROP.equals(propertyId)) {
return Integer.toString(location.y);
}
if (HEIGHT_PROP.equals(propertyId)) {
return Integer.toString(size.height);
}
if (WIDTH_PROP.equals(propertyId)) {
return Integer.toString(size.width);
}
return super.getPropertyValue(propertyId);
}
/** *//**
* Set the property value for the given property id.
* If no matching id is found, the call is forwarded to the superclass.
* <p>The property view uses the IDs from the IPropertyDescriptors array to set the
values
* of the corresponding properties.</p>
*/
public void setPropertyValue(Object propertyId, Object value) {
if (XPOS_PROP.equals(propertyId)) {
int x = Integer.parseInt((String) value);
setLocation(new Point(x, location.y));
} else if (YPOS_PROP.equals(propertyId)) {
int y = Integer.parseInt((String) value);
setLocation(new Point(location.x, y));
} else if (HEIGHT_PROP.equals(propertyId)) {
int height = Integer.parseInt((String) value);
setSize(new Dimension(size.width, height));
} else if (WIDTH_PROP.equals(propertyId)) {
int width = Integer.parseInt((String) value);
setSize(new Dimension(width, size.height));
} else {
super.setPropertyValue(propertyId, value);
}
}
我們首先定義一個(gè)IPropertyDescriptor類型的數(shù)組，然后初始化這個(gè)數(shù)組，該數(shù)組存放要顯示活動(dòng)的屬性，這里我們顯示活動(dòng)圖形的坐標(biāo)，大小屬性，由于屬性頁既能顯示屬性，還能編輯屬性，而坐標(biāo)和大小屬性只能輸入數(shù)字，所以我們加入了校驗(yàn)，如果給這些屬性輸入字符，就拋異常。getPropertyValue方法就是得到IPropertyDescriptor數(shù)組中對(duì)應(yīng)屬性名的屬性值，setPropertyValue方法就是對(duì)屬性值進(jìn)行修改時(shí)，要同時(shí)修改模型的屬性，讓模型通知控制器來刷新視圖，例如我們修改坐標(biāo)x的值，編輯器中活動(dòng)
的位置就要發(fā)生改變，