如何遍历Android中的SpannedString或SpannableString中的跨度

如果我有一个SpannedString(或SpannableString) like this

SpannableString spannableString = new SpannableString("Hello World!");
ForegroundColorSpan foregroundSpan = new ForegroundColorSpan(Color.RED);
BackgroundColorSpan backgroundSpan = new BackgroundColorSpan(Color.YELLOW);
spannableString.setSpan(foregroundSpan,1,8,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
spannableString.setSpan(backgroundSpan,3,spannableString.length() - 1,Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
textView.setText(spannableString);

如何循环生成的String的跨度？

解决方法

按顺序循环跨越

您可以使用getSpans在Spanned或Spannable String中获取跨度数组.但是,只需循环遍历getSpans结果将为not necessarily give them to you in order.为了使它们按顺序排列,您可以使用nextSpanTransition.

下面是一个SpannedString示例,如问题中的示例. (SpannableString的工作方式相同.)绿线表示跨度转换的位置.默认情况下,文本为黑色.

代码找到下一个跨度转换,然后获取当前范围内的所有跨度.

int next;
for (int i = 0; i < spannableString.length(); i = next) {

    // find the next span transition
    next = spannableString.nextSpanTransition(i,spannedString.length(),CharacterStyle.class);

    // get all spans in this range
    int numOfSpans = 0;
    CharacterStyle[] spans = spannableString.getSpans(i,next,CharacterStyle.class);
    for(int j = 0; j < spans.length; j++) {
        numOfSpans++;
    }

    Log.i("TAG","spans from " + i + " to " + next + ": " + numOfSpans);
}

输出：

spans from 0 to 1: 0
spans from 1 to 3: 1
spans from 3 to 8: 2
spans from 8 to 11: 1
spans from 11 to 12: 0

感谢this code的想法.

跨度的类型

通常在循环跨越时,您会选择某种类型的跨度.例如,如果要删除所有前景颜色跨度,可以执行以下操作：

// get spans
ForegroundColorSpan[] spans = spannableString.getSpans(0,spannableString.length(),ForegroundColorSpan.class);

// loop through spans
for (ForegroundColorSpan span : spans) {
    spannableString.removeSpan(span);
}

请注意,这不适用于SpannedString,因为SpannedString中的跨距不可变(请参阅this answer).

如果您想获得任何类型的所有跨度,您可以将类型设置为Object.class.

Object[] spans = spannableString.getSpans(0,Object.class);

如果您想要在角色级别影响外观的所有跨度,则可以使用CharacterStyle.class.如果在循环内你想进一步限制跨度到属于MetricAffectingSpan的那些,你可以这样做.

CharacterStyle[] spans = spannableString.getSpans(0,CharacterStyle.class);
for (CharacterStyle span : spans) {
    if (span instanceof MetricAffectingSpan) {
        // do something
    }
}

以下是范围类型的一般分层细分.它可能不完整.有关更多信息,请阅读Spans,a Powerful Concept.

Object
    CharacterStyle
        BackgroundColorSpan
        ClickableSpan
            URLSpan
        ForegroundColorSpan
        MaskFilterSpan
        StrikethroughSpan
        SuggestionSpan
        Underlinespan 
        MetricAffectingSpan
            AbsoluteSizeSpan
            LocaleSpan
            RelativeSizeSpan
            ReplacementSpan
                DynamicDrawableSpan
                    ImageSpan 
            ScaleXSpan
            StyleSpan
            SubscriptSpan
            SuperscriptSpan
            TextAppearanceSpan
            TypefaceSpan 
    ParagraphStyle
        AlignmentSpan
            AlignmentSpan.Standard
        BulletSpan
        DrawableMarginSpan
        IconMarginSpan
        LeadingMarginSpan
            LeadingMarginSpan.LeadingMarginSpan2
            LeadingMarginSpan.Standard
        LineBackgroundSpan
        LineHeightSpan
            LineHeightSpan.WithDensity
        QuoteSpan
        TabStopSpan
            TabStopSpan.Standard
        WrapTogetherSpan