Android SpannableString使用示例

有時候可以看到一些文本承載了不同風格的樣式，比如背景色、下劃線、下標、附帶表情圖等等
其實這些都可以通過SpannableString來完成，通過爲之設置不同的Span屬性，使不同的風格樣式組合在一起，然後再將文本信息傳給TextView，就可以呈現出絢麗多彩的效果

主要使用到的是 SpannableString 對象的 setSpan 方法，方法簽名如下所示：

     public void setSpan(Object what, int start, int end, int flags);

參數說明：

1. what 要設置的各種Span樣式
2. start 樣式的起始位置，樣式在該位置上起作用，索引從0開始
3. end 樣式的結束位置，樣式在該位置上不起作用
4. flags 設置當起始位置前和起始位置後如果再插入新字符時的動作，即是否對新插入的字符應用同樣的樣式
   
   • Spanned.SPAN_EXCLUSIVE_EXCLUSIVE： 前後都不包括，即前後位置都不會應用同樣的樣式
   • Spanned.SPAN_EXCLUSIVE_INCLUSIVE： 前面不會，後面會
   • Spanned.SPAN_INCLUSIVE_EXCLUSIVE： 前面會，後面不會
   • Spanned.SPAN_INCLUSIVE_INCLUSIVE： 前後都會

所有的示例代碼如下所示：

private void foregroundColorSpan() {
        SpannableString spannableString = new SpannableString("這是前景色");
        TextView tv_foregroundColorSpan = (TextView) findViewById(R.id.tv_foregroundColorSpan);
        ForegroundColorSpan foregroundColorSpan = new ForegroundColorSpan(Color.parseColor("#FF4081"));
        spannableString.setSpan(foregroundColorSpan, 2, spannableString.length(), Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
        tv_foregroundColorSpan.setText(spannableString);
    }

    private void backgroundColorSpan() {
        SpannableString spannableString = new SpannableString("這是背景色");
        TextView tv_backgroundColorSpan = (TextView) findViewById(R.id.tv_backgroundColorSpan);
        BackgroundColorSpan colorSpan = new BackgroundColorSpan(Color.parseColor("#30cfff"));
        spannableString.setSpan(colorSpan, 2, spannableString.length(), Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
        tv_backgroundColorSpan.setText(spannableString);
    }

    private void relativeSizeSpan() {
        SpannableString spannableString = new SpannableString("可以設置相對字體大小");
        TextView tv_relativeSizeSpan = (TextView) findViewById(R.id.tv_relativeSizeSpan);
        //相對於默認字體大小的倍數
        RelativeSizeSpan sizeSpan01 = new RelativeSizeSpan(1.2f);
        RelativeSizeSpan sizeSpan02 = new RelativeSizeSpan(1.4f);
        RelativeSizeSpan sizeSpan03 = new RelativeSizeSpan(1.6f);
        RelativeSizeSpan sizeSpan04 = new RelativeSizeSpan(1.8f);
        spannableString.setSpan(sizeSpan01, 4, 5, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan02, 5, 6, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan03, 6, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan04, 7, 8, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_relativeSizeSpan.setText(spannableString);
    }

    private void absoluteSizeSpan() {
        SpannableString spannableString = new SpannableString("可以設置絕對字體大小");
        TextView tv_absoluteSizeSpan = (TextView) findViewById(R.id.tv_absoluteSizeSpan);
        AbsoluteSizeSpan sizeSpan01 = new AbsoluteSizeSpan(12, true);
        AbsoluteSizeSpan sizeSpan02 = new AbsoluteSizeSpan(14, true);
        AbsoluteSizeSpan sizeSpan03 = new AbsoluteSizeSpan(16, true);
        AbsoluteSizeSpan sizeSpan04 = new AbsoluteSizeSpan(18, true);
        spannableString.setSpan(sizeSpan01, 4, 5, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan02, 5, 6, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan03, 6, 7, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(sizeSpan04, 7, 8, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_absoluteSizeSpan.setText(spannableString);
    }

    private void typeface() {
        SpannableString spannableString = new SpannableString("可以設置字體");
        TextView tv_typeface = (TextView) findViewById(R.id.tv_typeface);
        TypefaceSpan typefaceSpan = new TypefaceSpan("sans-serif");
        spannableString.setSpan(typefaceSpan, 4, spannableString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        tv_typeface.setText(spannableString);
    }

    private void strikethroughSpan() {
        SpannableString spannableString = new SpannableString("設置刪除線");
        TextView tv_strikethroughSpan = (TextView) findViewById(R.id.tv_strikethroughSpan);
        StrikethroughSpan strikethroughSpan = new StrikethroughSpan();
        spannableString.setSpan(strikethroughSpan, 2, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_strikethroughSpan.setText(spannableString);
    }

    private void underlineSpan() {
        SpannableString spannableString = new SpannableString("設置下劃線");
        TextView tv_underlineSpan = (TextView) findViewById(R.id.tv_underlineSpan);
        UnderlineSpan underlineSpan = new UnderlineSpan();
        spannableString.setSpan(underlineSpan, 2, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_underlineSpan.setText(spannableString);
    }

    private void superscriptSpan() {
        SpannableString spannableString = new SpannableString("設置上標");
        TextView tv_superscriptSpan = (TextView) findViewById(R.id.tv_superscriptSpan);
        SuperscriptSpan superscriptSpan = new SuperscriptSpan();
        spannableString.setSpan(superscriptSpan, 2, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_superscriptSpan.setText(spannableString);
    }

    private void subscriptSpan() {
        SpannableString spannableString = new SpannableString("設置下標");
        TextView tv_subscriptSpan = (TextView) findViewById(R.id.tv_subscriptSpan);
        SubscriptSpan subscriptSpan = new SubscriptSpan();
        spannableString.setSpan(subscriptSpan, 2, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_subscriptSpan.setText(spannableString);
    }

    private void styleSpan() {
        SpannableString spannableString = new SpannableString("設置各種不同的字體風格：葉應是葉");
        TextView tv_styleSpan = (TextView) findViewById(R.id.tv_styleSpan);
        StyleSpan bold = new StyleSpan(Typeface.BOLD);
        StyleSpan italic = new StyleSpan(Typeface.ITALIC);
        StyleSpan boldItalic = new StyleSpan(Typeface.BOLD_ITALIC);
        spannableString.setSpan(bold, 12, 13, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(italic, 13, 14, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        spannableString.setSpan(boldItalic, 14, 16, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_styleSpan.setText(spannableString);
    }

    private void imageSpan() {
        SpannableString spannableString = new SpannableString("添加表情圖片 ");
        TextView tv_imageSpan = (TextView) findViewById(R.id.tv_imageSpan);
        Drawable drawable = ContextCompat.getDrawable(this, R.drawable.icon);
        drawable.setBounds(0, 0, 44, 44);
        ImageSpan imageSpan = new ImageSpan(drawable);
        spannableString.setSpan(imageSpan, 5, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_imageSpan.setText(spannableString);
    }

    private void clickableSpan() {
        SpannableString spannableString = new SpannableString("這是可以點擊的文本：葉應是葉");
        TextView tv_clickableSpan = (TextView) findViewById(R.id.tv_clickableSpan);
        MyClickableSpan clickableSpan = new MyClickableSpan();
        spannableString.setSpan(clickableSpan, 10, spannableString.length(), Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
        tv_clickableSpan.setMovementMethod(LinkMovementMethod.getInstance());
        tv_clickableSpan.setText(spannableString);
    }

    private void urlSpan() {
        SpannableString spannableString = new SpannableString("這是可以跳轉到指定網頁的文本：葉應是葉");
        TextView tv_urlSpan = (TextView) findViewById(R.id.tv_urlSpan);
        URLSpan urlSpan = new URLSpan("https://github.com/leavesC");
        spannableString.setSpan(urlSpan, 15, spannableString.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
        tv_urlSpan.setMovementMethod(LinkMovementMethod.getInstance());
        tv_urlSpan.setHighlightColor(Color.parseColor("#303F9F"));
        tv_urlSpan.setText(spannableString);
    }

    private class MyClickableSpan extends android.text.style.ClickableSpan {

        @Override
        public void updateDrawState(TextPaint ds) {
            ds.setColor(Color.parseColor("#004081"));
            //設置是否顯示下劃線
            ds.setUnderlineText(false);
        }

        @Override
        public void onClick(View widget) {
            Intent intent = new Intent(MainActivity.this, MainActivity.class);
            startActivity(intent);
        }
    }

這裏提供源代碼下載：Android SpannableString使用示例