Question

我需要能够检测用户正在查看的当前语言是否是阿拉伯语的RTL（从右到左）语言。

目前我只是根据系统属性user.language中的语言代码检测到这一点，但必须有更好的方法。

Answer 1

ComponentOrientation.getOrientation(new Locale(System.getProperty("user.language"))).isLeftToRight();

Resource

Answer 2

我觉得有点脏，依赖于AWT课程，这些课程已经过时了，我正在处理BCP-47语言代码，所以我最终从Google Closure模板中复制了这些代码：

/**
 * A regular expression for matching right-to-left language codes.
 * See {@link #isRtlLanguage} for the design.
 */
private static final Pattern RtlLocalesRe = Pattern.compile(
    "^(ar|dv|he|iw|fa|nqo|ps|sd|ug|ur|yi|.*[-_](Arab|Hebr|Thaa|Nkoo|Tfng))" +
    "(?!.*[-_](Latn|Cyrl)($|-|_))($|-|_)");
/**
 * Check if a BCP 47 / III language code indicates an RTL language, i.e. either:
 * - a language code explicitly specifying one of the right-to-left scripts,
 *   e.g. "az-Arab", or<p>
 * - a language code specifying one of the languages normally written in a
 *   right-to-left script, e.g. "fa" (Farsi), except ones explicitly specifying
 *   Latin or Cyrillic script (which are the usual LTR alternatives).<p>
 * The list of right-to-left scripts appears in the 100-199 range in
 * http://www.unicode.org/iso15924/iso15924-num.html, of which Arabic and
 * Hebrew are by far the most widely used. We also recognize Thaana, N'Ko, and
 * Tifinagh, which also have significant modern usage. The rest (Syriac,
 * Samaritan, Mandaic, etc.) seem to have extremely limited or no modern usage
 * and are not recognized.
 * The languages usually written in a right-to-left script are taken as those
 * with Suppress-Script: Hebr|Arab|Thaa|Nkoo|Tfng  in
 * http://www.iana.org/assignments/language-subtag-registry,
 * as well as Sindhi (sd) and Uyghur (ug).
 * The presence of other subtags of the language code, e.g. regions like EG
 * (Egypt), is ignored.
 */
public static boolean isRtlLanguage(String languageString) {
  return languageString != null &&
      RtlLocalesRe.matcher(languageString).find();
}

请参阅https://closure-templates.googlecode.com/svn-history/r21/trunk/java/src/com/google/template/soy/internal/i18n/BidiUtils.java

Answer 3

TextUtils.getLayoutDirectionFromLocale(locale)

javadoc

Answer 4

添加一个布尔资源is_rtl（假设为）

在res/values/values.xml中
```
<bool name="is_rtl">false</bool>
```
在res/values-ldrtl/values.xml中
```
<bool name="is_rtl">true</bool>
```

然后，在Java中，您可以获得此布尔资源，并立即知道用户是否在RTL语言环境中。

有没有办法在Java中检测RTL语言？

4 个答案: