Android：如何将 Spannable.setSpan 与 String.format 结合起来？

Question

我将 Span 设置为文本的一部分。 Span 本身效果很好。但是，文本是由 Resources 中的 String.format 创建的，我不知道部分的 start 和 end在文本中我将设置 Span 为。

我尝试在 strings.xml 中使用自定义 HTML 标记，但 getText 或 getString 删除了它们。我可以使用类似这样的 getString(R.string.text, "" + arg + "")，然后使用 Html.fromHtml()，因为 arg 正是我想要设置 Span 的位置。

我看到 这种方法使用格式为“普通文本##span此处##普通文本”的文本。它解析字符串，删除标签并设置 Span。

有没有更好的方法将 Span 设置为格式化字符串，例如 "something %s some" 或者我应该使用上述方法之一？

Answer 1

getText() 将返回包含 strings.xml 中定义的格式的 SpannedString 对象。我创建了 自定义String.format 的版本，它将保留格式字符串中的任何范围，即使它们包含格式说明符（SpannedString 参数中的范围）也被保留）。像这样使用它：

Spanned toDisplay = SpanFormatter.format(getText(R.string.foo), bar, baz, quux);

Answer 2

我决定编写一个由 George 提供的 此处 的 Kotlin 版本，以防有一天链接消失：

/*
* Copyright © 2014 George T. Steel
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//https://github.com/george-steel/android-utils/blob/master/src/org/oshkimaadziig/george/androidutils/SpanFormatter.java
/**
 * Provides [String.format] style functions that work with [Spanned] strings and preserve formatting.
 *
 * @author George T. Steel
 */
object SpanFormatter {
    private val FORMAT_SEQUENCE: Pattern = Pattern.compile("%([0-9]+\\$|<?)([^a-zA-z%]*)([[a-zA-Z%]&&[^tT]]|[tT][a-zA-Z])")

    /**
     * Version of [String.format] that works on [Spanned] strings to preserve rich text formatting.
     * Both the `format` as well as any `%s args` can be Spanned and will have their formatting preserved.
     * Due to the way [android.text.Spannable]s work, any argument's spans will can only be included **once** in the result.
     * Any duplicates will appear as text only.
     *
     * @param format the format string (see [java.util.Formatter.format])
     * @param args
     * the list of arguments passed to the formatter. If there are
     * more arguments than required by `format`,
     * additional arguments are ignored.
     * @return the formatted string (with spans).
     */
    fun format(format: CharSequence?, vararg args: Any?): SpannedString {
        return format(java.util.Locale.getDefault(), format, *args)
    }

    /**
     * Version of [String.format] that works on [Spanned] strings to preserve rich text formatting.
     * Both the `format` as well as any `%s args` can be Spanned and will have their formatting preserved.
     * Due to the way [android.text.Spannable]s work, any argument's spans will can only be included **once** in the result.
     * Any duplicates will appear as text only.
     *
     * @param locale
     * the locale to apply; `null` value means no localization.
     * @param format the format string (see [java.util.Formatter.format])
     * @param args
     * the list of arguments passed to the formatter.
     * @return the formatted string (with spans).
     * @see String.format
     */
    fun format(locale: java.util.Locale, format: CharSequence?, vararg args: Any?): SpannedString {
        val out = SpannableStringBuilder(format)
        var i = 0
        var argAt: Int = -1
        while (i < out.length) {
            val m: java.util.regex.Matcher = FORMAT_SEQUENCE.matcher(out)
            if (!m.find(i))
                break
            i = m.start()
            val exprEnd: Int = m.end()
            val argTerm: String? = m.group(1)
            val modTerm: String? = m.group(2)
            val typeTerm: String? = m.group(3)
            var cookedArg: CharSequence
            when (typeTerm) {
                "%" -> cookedArg = "%"
                "n" -> cookedArg = "\n"
                else -> {
                    val argIdx: Int = when (argTerm) {
                        "" -> ++argAt
                        "<" -> argAt
                        else -> argTerm!!.substring(0, argTerm.length - 1).toInt() - 1
                    }
                    val argItem: Any? = args[argIdx]
                    cookedArg = if ((typeTerm == "s") && argItem is Spanned) {
                        argItem
                    } else {
                        String.format(locale, "%$modTerm$typeTerm", argItem)
                    }
                }
            }
            out.replace(i, exprEnd, cookedArg)
            i += cookedArg.length
        }
        return SpannedString(out)
    }
}

Answer 3

我通过引入 TaggedArg 类解决了这个问题，该类的实例扩展为 value。然后我创建了负责读取包含标签的文本并用跨度替换这些标签的对象。不同的跨度在地图标签->工厂中注册。

有一个小惊喜。如果您有类似 "somethingSomething" 的文本，Html.fromHtml 会将该文本读取为 "something Something< /xx>”。我必须在整个文本周围添加标签 来防止这种情况发生。

Answer 4

乔治认为的 getText() 方式很有趣。但不需要额外编写一个类。 getText() 返回一个 CharSequence。因此，使用 SpannableStringBuilder 将其设置为 TextView：

textViewCell.setText(new SpannableStringBuilder(getText(R.string.foo));

在 strings.xml 中，您可以使用 html 标签编写它（不要忘记文本前后的引号）：

<string name="foo">"CO<sub><small>2</small></sub>"</string>

这种标记对我有用手动将其设置为 textView （如上）或将其分配到布局中。