dflorey 2004/10/05 10:47:55 Modified: i18n/xdocs navigation.xml index.xml Added: i18n/xdocs quickstart.xml Log: Documentation added Revision Changes Path 1.2 +1 -0 jakarta-commons-sandbox/i18n/xdocs/navigation.xml Index: navigation.xml =================================================================== RCS file: /home/cvs/jakarta-commons-sandbox/i18n/xdocs/navigation.xml,v retrieving revision 1.1 retrieving revision 1.2 diff -u -r1.1 -r1.2 --- navigation.xml 4 Oct 2004 13:41:10 -0000 1.1 +++ navigation.xml 5 Oct 2004 17:47:55 -0000 1.2 @@ -5,6 +5,7 @@ <body> <menu name="Commons Transaction"> <item name="Overview" href="/index.html" /> + <item name="Getting started" href="/quickstart.html" /> <item name="API Documentation" href="/apidocs/index.html"/> <item name="Downloads" href="/downloads.html"/> </menu> 1.2 +9 -2 jakarta-commons-sandbox/i18n/xdocs/index.xml Index: index.xml =================================================================== RCS file: /home/cvs/jakarta-commons-sandbox/i18n/xdocs/index.xml,v retrieving revision 1.1 retrieving revision 1.2 diff -u -r1.1 -r1.2 --- index.xml 4 Oct 2004 13:41:10 -0000 1.1 +++ index.xml 5 Oct 2004 17:47:55 -0000 1.2 @@ -9,8 +9,15 @@ <body> -<section name="The I18n Component"> -<p>Provides a set of classes dealing with internationalization issues.</p> +<section name="The I18 Component"> +<p>Developing a localized application is supported by the Java language in a comfortable way. +This package adds the feature of localized message bundles that consist of one or many localized +texts that belong together. Think of an error message that consists of title, text, summary and +error details. These localized texts are bundled to a localized error and can be referenced easily.</p> + <p>Based on this concept localized exceptions are introduced that make dealing with internationalization a pleasure...</p> + <p>A message manager takes care of initializing the messages from an XML document. + It can handle a number of different message resource so that you can quickly reload messages based + on a single resource.</p> </section> <section name="Releases"> 1.1 jakarta-commons-sandbox/i18n/xdocs/quickstart.xml Index: quickstart.xml =================================================================== <?xml version="1.0"?> <document> <properties> <title>Quickstart</title> <author email="[EMAIL PROTECTED]">Commons Documentation Team</author> </properties> <body> <section name="Getting started"> <p>In order to get an impression of how this component works, we will start with an example showing the capabilities of this package.</p> <p>To get started you need at least the jar of this component and the dependent xml-importer-jar for reading xml documents in your classpath.</p> </section> <section name="Defining the messages"> <p>You have to initialize the message manager with an input stream giving access to the xml document containing the localized messages.</p> <source> <?xml version="1.0" encoding="UTF-8" ?> <messages> <message id="welcome"> <locale language="en"> <entry key="text">Welcome</entry> </locale> <locale language="de"> <entry key="text">Willkommen</entry> </locale> </message> <message id="usage"> <locale language="en"> <entry key="title">Usage</entry> <entry key="text">The application requires the following parameters:</entry> </locale> <locale language="de"> <entry key="title">Benutzung</entry> <entry key="text">Die folgenden Parameter werden erwartet:</entry> </locale> </message> <message id="validationFailed"> <locale language="en"> <entry key="title">Parameter {0} invalid</entry> <entry key="text">The given value of the parameter {0} is invalid</entry> <entry key="summary">Value of parameter {0} invalid</entry> <entry key="details">The given value {1} of parameter {0} is invalid.</entry> </locale> <locale language="de"> <entry key="title">Parametervalidierung fehlgeschlagen.</entry> <entry key="text">Die Validierung des Parameters {0} ist fehlgeschlagen.</entry> <entry key="summary">Validierung des Parameters {0} fehlgeschlagen.</entry> <entry key="details">Der Wert {1} des Parameters {0} ist ungültig.</entry> </locale> </message> </messages> </source> <p>This is an example that shows how to create localized bundles. As you can see each message is identified by a message id and contains the bundled messages for the defined locales. The language identifiers are well known from the <code>Locale</code> class and support language variants and the appropriate fallback mechanism.</p> <p>Each bundle can consist of a number of message entries that belong to this bundle. You are free to add as many entries to each bundle as you like. The I18n component contains a number of classes that simplify the access to entries of frequently used bundles.</p> </section> <section name="Initializing the messages"> <p>Now that we created a file containing the desired messages, we want to make use of them. To do so we have to initialize the <code>MessageManager</code> with these messages.</p> <source> ... try { FileInputStream inputStream = new FileInputStream("myMessages.xml"); MessageManager.install("myMessages", inputStream); } catch ( FileNotFoundException e ) { // handle exception } ... </source> <p>As you can see it is very easy to install new messages. All you need is an appropriate input stream to access the xml messages.</p><p>Why is the manager initialized with an input stream and not using a file name? You might want to use the i18n component within web applications where you want probably load messages from you .war archive. So an input stream is much more flexible, even if it is a little bit more unconvenient than using a file name in our use case.</p> </section> <section name="Using message bundles"> <p>Now we are ready to go! First of all we want to print out a simple localized welcome message to the user. There are different way to do so: We can call the <code>MessageManager</code> directly by asking for a specific entry of a message:</p> <source> ... System.out.println(MessageManager.getText("welcome", "text", new Object[0], Locale.getDefault())); ... </source> <p>If you are familiar with text formatting in Java you will have guessed correctly that you have the ability to pass arguments to the localized text. In our case we don't pass any arguments but just an empty object array.</p> <p>The previous example might be useful if you want to print out some localized message quick and dirty, but the recommended way is the following:</p> <source> ... LocalizedText welcome = new LocalizedText("welcome"); // Using the default locale System.out.println(welcome.getText()); // Using some other locale System.out.println(welcome.getText(Locale.GERMAN)); ... </source> <p>In this example we make use of the predefined message bundle called <code>LocalizedText</code> that just consists of a single text element. The advantage of this approach is, that you avoid misspelling as you have getter-methods for each entry. You also have the ability to pass some default text that will be used if the message was not found:</p> <source> ... LocalizedText welcome = new LocalizedText("undefined"); System.out.println(welcome.getText("notFound")); ... </source> <p>As the <code>MessageManager</code> can not find the message with id <code>undefined</code>, a <code>MessageNotFoundeException</code> is thrown. This one is a <code>RuntimeException</code> as this avoids bloating up the code with exception handling.</p> <p>The <code>LocalizedText</code> handles this exception and returns the given default text instead.</p> </section> <section name="Using localized exceptions"> <p>The concept of message bundles is very useful when it comes to exception handling. You can simple create a <code>LocalizedException</code> that will be constructed with a <code>LocalizedError</code> object containing title, text, summary and details of the exception. In addition you can specify the causing exception:</p> <source> ... try { doSomething(); } catch ( SomeException exception ) { throw new LocalizedException( new LocalizedError("somethingFailed", new Object[] { agrument1 }), exception); } ... </source> <p>The big advantage of this approach is that you can create localized exceptions with all arguments that are describing the error in detail and print out localized details including this arguments lateron. Have a look at the Slide Projector to see how this can simplify your life ;-)</p> </section> <section name="Releases"> <p> See the <a href="downloads.html">downloads</a> page for information on obtaining releases. </p> </section> <section name="Documentation"> <p> The <a href="apidocs/index.html">JavaDoc API documents</a> are available online. </p> </section> </body> </document>
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