我遇到以下问题,即我将JTextPane与HTMLEditorKit结合使用,并向窗格动态添加内容。内容可以跨越几行,还包含很多图像(小图标)。现在的问题是,如果我通过以下方式插入一堆带有图标的文本:
editorKit.insertHTML(doc, doc.getLength(), htmlCode, 0, 0, null);
结果是html代码中的图像需要很长时间才能显示在屏幕上(〜1秒):
问题:有没有办法通过以下方法来缓冲窗格中显示的图像(如果是html代码):
imgsrc = "file:/" + imgSRCOnHDD;
imgsrc = imgsrc.replace("\\", "/");
imgSub = "<img height=\"18\" width=\"18\" style=\"vertical-align:middle;\" src='" + imgsrc + "'></img>";
由于HTMLEditor,我无法使用pane.insertIcon。是否可能需要某种容器将其设置为不可见,将内容添加到窗格中,然后再将容器设置为可见?
最佳答案
@StanislavL的评论使我解决了这个问题,尽管不是他提供的链接,但是它没有用,而且我无法查明原因,我再次检查了URL的正确性,但是在设置了缓存后,窗格始终会显示“断开的链接”每张图片的图片。因此,我在了解HTMLEditorKit的缓存机制的情况下找到了这篇文章:
https://stackoverflow.com/a/27669916/7377320
提到的代码:
public class ImageCache extends Hashtable {
public Object get(Object key) {
Object result = super.get(key);
if (result == null){
result = Toolkit.getDefaultToolkit().createImage((URL) key);
put(key, result);
}
return result;
}
}
...
Dictionary cache = (Dictionary) pane.getDocument().getProperty("imageCache");
if (cache == null) {
cache = new ImageCache();
pane.getDocument().putProperty("imageCache", cache);
}
完美无缺,现在可以正常工作。我还对HTMLEditorKit的ImageView进行了更改:
public class MyImageView extends ImageView {
public MyImageView(Element elem) {
super(elem);
}
@Override
public Icon getNoImageIcon() {
return null;
}
@Override
public Icon getLoadingImageIcon() {
return null;
}
}
这将不再在窗格中显示任何断开的链接图片,也不会“预加载”断开的链接图片。
HTMLEditorKit:
public class MyHTMLEditorKit extends HTMLEditorKit {
@Override
public ViewFactory getViewFactory() {
return new HTMLEditorKit.HTMLFactory() {
public View create(Element e) {
View v = super.create(e);
Object o = e.getAttributes().getAttribute(StyleConstants.NameAttribute);
if (o instanceof HTML.Tag) {
HTML.Tag kind = (HTML.Tag) o;
if (kind == HTML.Tag.IMG) {
return new MyImageView(e);
}
}
if (v instanceof InlineView) {
return new InlineView(e) {
public int getBreakWeight(int axis, float pos, float len) {
return View.GoodBreakWeight;
}
public View breakView(int axis, int p0, float pos, float len) {
if (axis == View.X_AXIS) {
checkPainter();
int p1 = getGlyphPainter().getBoundedPosition(this, p0, pos, len);
if (p0 == getStartOffset() && p1 == getEndOffset()) {
return this;
}
return createFragment(p0, p1);
}
return this;
}
};
} else if (v instanceof ParagraphView) {
return new ParagraphView(e) {
protected javax.swing.SizeRequirements calculateMinorAxisRequirements(int axis, javax.swing.SizeRequirements r) {
if (r == null) {
r = new javax.swing.SizeRequirements();
}
float pref = layoutPool.getPreferredSpan(axis);
float min = layoutPool.getMinimumSpan(axis);
// Don't include insets, Box.getXXXSpan will include them.
r.minimum = (int) min;
r.preferred = Math.max(r.minimum, (int) pref);
r.maximum = Integer.MAX_VALUE;
r.alignment = 0.5f;
return r;
}
};
}
return v;
}
};
}
}