学而实习之 不亦乐乎

Android 中 SpannableString 的用法

2022-08-03 08:32:26

如何在 Android 中实现多彩多样的文本？比如不同颜色的文本、带有图片的文本、带有删除线的文本等，看起来这个需求很复杂，其实在Android 中通过 SpannableString 很容易实现。

一、SpannableString 简介

SpannableString，是 CharSequence 的一种，原本的 CharSequence 只是一串字符序列，没有任何样式，而 SpannableString 可以在字符序列基础上对指定的字符进行润饰，在开发中，TextView 可以通过 setText(CharSequence) 传入 SpannableString 作为参数，来达到显示不同样式文字的效果。


二、SpannableString 使用

SpannableString 的使用主要通过 setSpan() 方法来实现。其定义如下：

方法：setSpan (Object what, int start, int end, int flags)
参数说明：

  1. object what：对应的各种Span；
  2. int start：开始应用指定Span的位置，索引从0开始；
  3. int end：结束应用指定Span的位置，特效并不包括这个位置。比如如果这里数为3（即第4个字符），第4个字符不会有任何特效。
  4. int flags：取值有如下四个
    • Spannable.SPAN_EXCLUSIVE_EXCLUSIVE：前后都不包括，即在指定范围的前面和后面插入新字符都不会应用新样式
    • Spannable.SPAN_EXCLUSIVE_INCLUSIVE：前面不包括，后面包括。即仅在范围字符的后面插入新字符时会应用新样式
    • Spannable.SPAN_INCLUSIVE_EXCLUSIVE：前面包括，后面不包括。
    • Spannable.SPAN_INCLUSIVE_INCLUSIVE：前后都包括。

三、常用 Span 及实例

1、ForegroundColorSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
ForegroundColorSpan foregroundColorSpan = new ForegroundColorSpan(Color.GREEN);
spannableString.setSpan(foregroundColorSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

2、BackgroudColorSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
BackgroundColorSpan backgroundColorSpan = new BackgroundColorSpan(Color.GREEN);
spannableString.setSpan(backgroundColorSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

3、ClickableSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
ClickableSpan clickableSpan = new ClickableSpan() {
    @Override
    public void onClick(View widget) {
        Toast.makeText(MainActivity.this, "如果我是杰克逊", Toast.LENGTH_SHORT).show();
    }
    @Override
    public void updateDrawState(TextPaint ds) {
        ds.setUnderlineText(false);
    }
};
spannableString.setSpan(clickableSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setMovementMethod(LinkMovementMethod.getInstance());
mTextView.setText(spannableString);

4、URLSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
URLSpan urlSpan = new URLSpan("https://www.baidu.com/s?ie=UTF-8&wd=杰克逊");
spannableString.setSpan(urlSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setMovementMethod(LinkMovementMethod.getInstance());
mTextView.setText(spannableString);

5、MaskFilterSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
MaskFilterSpan embossMaskFilterSpan =
    new MaskFilterSpan(new EmbossMaskFilter(new float[]{10, 10, 10}, 0.5f, 1, 1));
spannableString.setSpan(embossMaskFilterSpan, 0, 4, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
RelativeSizeSpan relativeSizeSpan = new RelativeSizeSpan(1.5f);
spannableString.setSpan(relativeSizeSpan, 0, 4, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
MaskFilterSpan blurMaskFilterSpan = new MaskFilterSpan(new BlurMaskFilter(10, Blur.NORMAL));
spannableString.setSpan(blurMaskFilterSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

6、RelativeSizeSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
RelativeSizeSpan relativeSizeSpan = new RelativeSizeSpan(1.5f);
spannableString.setSpan(relativeSizeSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

7、AbsoluteSizeSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
AbsoluteSizeSpan absoluteSizeSpan = new AbsoluteSizeSpan(40, true);
spannableString.setSpan(absoluteSizeSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString)

8、ScaleXSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
ScaleXSpan scaleXSpan= new ScaleXSpan(1.5f);
spannableString.setSpan(scaleXSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

9、StyleSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
StyleSpan boldSpan = new StyleSpan(Typeface.BOLD);
StyleSpan italicSpan = new StyleSpan(Typeface.ITALIC);
StyleSpan boldItalicSpan = new StyleSpan(Typeface.BOLD_ITALIC);
spannableString.setSpan(boldSpan, 0, 2, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(italicSpan, 2, 4, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(boldItalicSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

10、TypefaceSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
TypefaceSpan monospace = new TypefaceSpan("monospace");
TypefaceSpan serif = new TypefaceSpan("serif");
TypefaceSpan sans_serif = new TypefaceSpan("sans-serif");
spannableString.setSpan(monospace, 0, 2, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(serif, 2, 4, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(sans_serif, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

11、TextAppearanceSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
TextAppearanceSpan textAppearanceSpan = new TextAppearanceSpan(this, android.R.style.TextAppearance_Material);
spannableString.setSpan(textAppearanceSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

12、UnderlineSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
UnderlineSpan underlineSpan = new UnderlineSpan();
spannableString.setSpan(underlineSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

13、StrikethroughSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
StrikethroughSpan strikethroughSpan = new StrikethroughSpan();
spannableString.setSpan(strikethroughSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

14、SuperscriptSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
SuperscriptSpan superscriptSpan = new SuperscriptSpan();
RelativeSizeSpan relativeSizeSpan = new RelativeSizeSpan(0.8f);
spannableString.setSpan(relativeSizeSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(superscriptSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

15、SubscriptSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
SubscriptSpan subscriptSpan = new SubscriptSpan();
RelativeSizeSpan relativeSizeSpan = new RelativeSizeSpan(0.8f);
spannableString.setSpan(relativeSizeSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
spannableString.setSpan(subscriptSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);

16、ImageSpan

SpannableString spannableString = new SpannableString("如果我是杰克逊");
ImageSpan imageSpan = new ImageSpan(this, R.drawable.ic_eason);
spannableString.setSpan(imageSpan, 4, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
mTextView.setText(spannableString);