_chapter 10.htm
来自「Core Java 2(中文名称：JAVA 2 核心技术 卷二：高级特性）这是英」· HTM 代码 · 共 1,361 行 · 第 1/4 页
HTM
1,361 行
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
<title>Chapter 10</title>
<link rel="stylesheet" type="text/css" href="docsafari.css">
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<ul></ul>
<table width="100%" border="1" bgcolor="#EBEBFF">
<tr>
<td width="5%" align="left" valign="middle"><a href="_chapter%209.htm"><img src="Larrow.gif" width="17" height="19" border="0"></a></td>
<td align="center" valign="middle"><a class="docLink" href="Front%20matter.htm">CONTENTS</a></td>
<td width="5%" align="right" valign="middle"><a href="_chapter%2011.htm"><img src="Rarrow.gif" width="17" height="19" border="0"></a></td>
</tr>
</table>
<h2 class="docChapterTitle">Chapter 10. Internationalization</h2>
<ul>
<li>
<p class="docList"><a class="docLink" href="#c10s1">Locales</a></li>
<li>
<p class="docList"><a class="docLink" href="#c10s2">Numbers and Currencies</a></li>
<li>
<p class="docList"><a class="docLink" href="#c10s3">Date and Time</a></li>
<li>
<p class="docList"><a class="docLink" href="#c10s4">Text</a></li>
<li>
<p class="docList"><a class="docLink" href="#c10s5">Resource Bundles</a></li>
<li>
<p class="docList"><a class="docLink" href="#c10s6">Graphical User Interface Localization</a></li>
</ul>
<p class="docText">There's a big world out there; we hope that lots of its
inhabitants will be interested in your application or applet. The Internet,
after all, effortlessly spans the barriers between countries. On the other hand,
when you write your applet in U.S. English, using the ASCII character set,
<span class="docEmphasis">you</span> are putting up a barrier. For example, even
within countries that can function using the ASCII character set, things as
basic as dates and numbers are displayed differently. To a German speaker, the
date 3/4/95 means something different than it does to an English speaker. Or, an
applet like our calculator from Chapter 10 of Volume 1 could confuse people who
do not use the "." to separate the integer and fractional parts of a number.</p>
<p class="docText">Now, it is true that many Internet users are able to read
English, but they will certainly be more comfortable with applets or
applications that are written in their own language and that present data in the
format with which they are most familiar. Imagine, for example, that you could
write a retirement calculator applet that would change how it displays its
results <span class="docEmphasis">depending on the location of the machine that
is downloading it.</span> This kind of applet is immediately more valuable梐nd
smart companies will recognize its value.</p>
<p class="docText">The Java programming language was the first language designed
from the ground up to support internationalization. From the beginning, it had
the one essential feature needed for effective internationalization: it used
Unicode for all strings. Unicode support makes it easy to write programs in the
Java programming language that manipulate strings in any one of multiple
languages.</p>
<div class="docNote">
<p class="docNoteTitle">NOTE</p>
<table cellSpacing="0" cellPadding="1" width="90%" border="0">
<tr>
<td vAlign="top" width="60">
<img alt="graphics/note.gif" src="note.gif" align="left" border="0" width="54" height="53"><br>
</td>
<td vAlign="top">
<p class="docText">The best source for Unicode character tables is <i>The
Unicode Standard, Version 3.0</i>, [Addison-Wesley<span class="docEmphasis">,</span>
2000]. You can also see many of the code charts at
<a class="docLink" href="http://www.unicode.org" target="_blank">
http://www.unicode.org</a>.</td>
</tr>
</table>
</div>
<p class="docText">Many programmers believe that all they need to do to
internationalize their application is to support Unicode and to translate the
messages in the user interface. However, as you will see in this chapter, there
is a lot more to internationalizing programs than just Unicode support.
Operating systems and even browsers may not necessarily be Unicode-ready. For
example, it is almost always necessary to have a translation layer between the
character sets and fonts of the host machine and the Unicode-centric Java
virtual machine. Also, dates, times, currencies梕ven numbers梐re formatted
differently in different parts of the world. You need an easy way to configure
menu and button names, message strings, and keyboard shortcuts for different
languages. You need to trigger the changes in a way that is based on information
the ambient machine can report to your program.</p>
<p class="docText">In this chapter, you'll see how to write internationalized
Java applications and applets. You will see how to localize date and time,
numbers and text, and graphical user interfaces, and you'll look at the tools
that the SDK offers for writing internationalized programs. (And, by the way,
you will see how to write a retirement calculator applet that can change how it
displays its results <span class="docEmphasis">depending on the location of the
machine that is downloading it.</span>)</p>
<h3 class="docSection1Title" id="c10s1">Locales</h3>
<p class="docText">When you look at an application that is adapted to an
international market, the most obvious difference you notice is the language.
This observation is actually a bit too limiting for true internationalization:
Countries can share a common language, but you still may need to do some work to
make computer users of both countries happy.<span id="ENB10-1"><a class="docLink" href="#EN10-1"><sup>[1]</sup></a></span></p>
<p class="docText">In all cases, menus, button labels, and program messages will
need to be translated to the local language; they may also need to be rendered
in a different script. There are many more subtle differences; for example,
numbers are formatted quite differently in English and in German. The number</p>
<pre>123,456.78
</pre>
<p class="docText">should be displayed as</p>
<pre>123.456,78
</pre>
<p class="docText">for a German user. That is, the role of the decimal point and
the decimal comma separator are reversed! There are similar variations in the
display of dates. In the United States, dates are somewhat irrationally
displayed as month/day/year. Germany uses the more sensible order of
day/month/year, whereas in China, the usage is year/month/day. Thus, the date</p>
<pre>3/22/61
</pre>
<p class="docText">should be presented as</p>
<pre>22.03.1961
</pre>
<p class="docText">to a German user. Of course, if the month names are written
out explicitly, then the difference in languages becomes apparent. The English</p>
<pre>March 22, 1961
</pre>
<p class="docText">should be presented as</p>
<pre>22. M鋜z 1961
</pre>
<p class="docText">in German, or</p>
<p> </p>
<center>
<p>
<img alt="graphics/10fig08.gif" src="10fig08.gif" border="0" width="130" height="25"><br>
</p>
</center>
<p class="docText">in Chinese.</p>
<p class="docText">You saw in Volume 1 that the <tt>java.text</tt> class has
methods that can format numbers, currencies, and dates. These methods can, in
fact, do much more when you give them a parameter that describes the location.
To invoke these methods in a non-country-specific way, you only have to supply
objects of the <tt>Locale</tt> class. A <span class="docEmphasis">locale</span>
describes</p>
<ul>
<li>
<p class="docList">A language;</li>
<li>
<p class="docList">A location;</li>
<li>
<p class="docList">Optionally, a variant.</li>
</ul>
<p class="docText">For example, in the United States, you use a locale with</p>
<blockquote>
<p class="docList">language=English, location=United States.</p>
</blockquote>
<p class="docText">In Germany, you use a locale with</p>
<blockquote>
<p class="docList">language=German, location=Germany.</p>
</blockquote>
<p class="docText">Switzerland has four official languages (German, French,
Italian, and Rhaeto-Romance). A German speaker in Switzerland would want to use
a locale with</p>
<blockquote>
<p class="docList">language=German, location=Switzerland</p>
</blockquote>
<p class="docText">This locale would make formatting work similarly to how it
would work for the German locale; however, currency values would be expressed in
Swiss francs, not German marks.</p>
<p class="docText">Variants are, fortunately, rare and are needed only for
exceptional or system-dependent situations. For example, the Norwegians are
having a hard time agreeing on the spelling of their language (a derivative of
Danish). They use two spelling rule sets: a traditional one called Bokm錶 and a
new one called Nynorsk. The traditional spelling would be expressed as a variant</p>
<blockquote>
<p class="docList">language=Norwegian, location=Norway, variant=Bokm錶</p>
</blockquote>
<p class="docText">There are "Euro" variants for several European locales. For
example, the locale</p>
<blockquote>
<p class="docList">language=German, location=Germany, variant=Euro</p>
</blockquote>
<p class="docText">uses the euro sign $ instead of DM for displaying currencies.</p>
<p class="docText">It is also possible to encode platform-dependent information
in the variant.</p>
<p class="docText">To express the language and location in a concise and
standardized manner, the Java programming language uses codes that were defined
by the International Standards Organization. The local language is expressed as
a lowercase two-letter code, following ISO-639, and the country code is
expressed as an uppercase two-letter code, following ISO-3166.
<a class="docLink" href="#ch10table01">Tables 10-1</a> and
<a class="docLink" href="#ch10table02">10-2</a> show some of the most common
codes.</p>
<div class="docNote">
<p class="docNoteTitle">NOTE</p>
<table cellSpacing="0" cellPadding="1" width="90%" border="0">
<tr>
<td vAlign="top" width="60">
<img alt="graphics/note.gif" src="note.gif" align="left" border="0" width="54" height="53"><br>
</td>
<td vAlign="top">
<p class="docText">For a full list of ISO-639 codes, see, for example,</p>
<p class="docText">
<a class="docLink" href="http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt" target="_blank">
http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt</a>.</p>
<p class="docText">You can find a full list of the ISO-3166 codes at a
number of sites, including</p>
<p class="docText">
<a class="docLink" href="http://www.niso.org/3166.html" target="_blank">
http://www.niso.org/3166.html</a>.</td>
</tr>
</table>
<p> </div>
<table cellSpacing="0" cellPadding="1" width="100%" border="1">
<caption>
<h5 id="ch10table01" class="docTableTitle">Table 10-1. Common ISO-639 language codes</h5>
</caption>
<colgroup span="2" align="left">
</colgroup>
<tr>
<th class="docTableHeader" vAlign="center"><span class="docEmphStrong">
Language</span> </th>
<th class="docTableHeader" vAlign="center"><span class="docEmphStrong">Code</span>
</th>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Chinese </td>
<td class="docTableCell" vAlign="top"><tt>zh</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Danish </td>
<td class="docTableCell" vAlign="top"><tt>da</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Dutch </td>
<td class="docTableCell" vAlign="top"><tt>nl</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">English </td>
<td class="docTableCell" vAlign="top"><tt>en</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">French </td>
<td class="docTableCell" vAlign="top"><tt>fr</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Finnish </td>
<td class="docTableCell" vAlign="top"><tt>fi</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">German </td>
<td class="docTableCell" vAlign="top"><tt>de</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Greek </td>
<td class="docTableCell" vAlign="top"><tt>el</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Italian </td>
<td class="docTableCell" vAlign="top"><tt>it</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Japanese </td>
<td class="docTableCell" vAlign="top"><tt>ja</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Korean </td>
<td class="docTableCell" vAlign="top"><tt>ko</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Norwegian </td>
<td class="docTableCell" vAlign="top"><tt>no</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Portuguese </td>
<td class="docTableCell" vAlign="top"><tt>pt</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Spanish </td>
<td class="docTableCell" vAlign="top"><tt>sp</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Swedish </td>
<td class="docTableCell" vAlign="top"><tt>sv</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Turkish </td>
<td class="docTableCell" vAlign="top"><tt>tr</tt> </td>
</tr>
</table>
<table cellSpacing="0" cellPadding="1" width="100%" border="1">
<caption>
<h5 id="ch10table02" class="docTableTitle">Table 10-2. Common ISO-3166 country codes</h5>
</caption>
<colgroup span="2" align="left">
</colgroup>
<tr>
<th class="docTableHeader" vAlign="top"><span class="docEmphStrong">Country</span>
</th>
<th class="docTableHeader" vAlign="top"><span class="docEmphStrong">Code</span>
</th>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Austria </td>
<td class="docTableCell" vAlign="top"><tt>AT</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Belgium </td>
<td class="docTableCell" vAlign="top"><tt>BE</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Canada </td>
<td class="docTableCell" vAlign="top"><tt>CA</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">China </td>
<td class="docTableCell" vAlign="top"><tt>CN</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Denmark </td>
<td class="docTableCell" vAlign="top"><tt>DK</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Finland </td>
<td class="docTableCell" vAlign="top"><tt>FI</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Germany </td>
<td class="docTableCell" vAlign="top"><tt>DE</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Great Britain </td>
<td class="docTableCell" vAlign="top"><tt>GB</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Greece </td>
<td class="docTableCell" vAlign="top"><tt>GR</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Ireland </td>
<td class="docTableCell" vAlign="top"><tt>IE</tt> </td>
</tr>
<tr>
<td class="docTableCell" vAlign="top">Italy </td>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?