This page contains some examples showing the capabilities of the i18n-compoenent. Most of the examples can be found in the components sources in the example-package.
The following example shows how to take advantage of detailed error information provided by localized exceptions. In the real world it is no good idea to create LocalizedExceptions directly, but to create your own subclasses of LocalizedException.
public class LocalizedExceptionExample {
private static final Logger logger = Logger
.getLogger(LocalizedExceptionExample.class.getName());
public static void main(String[] args) {
// Install the file providing the required messages for this example
MessageManager.addMessageProvider("org.apache.commons-i18n.examples",
new XMLMessageProvider(Thread.currentThread().getContextClassLoader().getResourceAsStream(
"exampleMessages.xml")));
// Simulate the locale of the current user in a multi-user environment
// such as a web application
Locale currentUsersLocale = Locale.GERMAN;
// This is the real part dealing with localized exceptions
try {
someMethodThrowingAnException();
} catch (LocalizedException exception) {
// Retrieve the detailed localized error message
ErrorBundle errorMessage = exception.getErrorMessage();
// Print the summary of this error to the log with level SEVERE
// using the VM default locale:
logger.log(Level.SEVERE, errorMessage.getSummary(Locale
.getDefault()));
// Print the details of this error to the log with level FINE
// using the VM default locale:
logger
.log(Level.FINE, errorMessage.getDetails(Locale
.getDefault()));
// Provide the title of this error to the user in a highly visible
// way
// using the current users locale:
System.out.println("#### "
+ errorMessage.getTitle(currentUsersLocale) + " ####");
// Provide the text of this error to the user
// using the current users locale:
System.out.println(errorMessage.getText(currentUsersLocale));
}
}
/**
* @throws LocalizedException
* is thrown just to show the capabilities of
* LocalizedExceptions
*/
private static void someMethodThrowingAnException()
throws LocalizedException {
String userCausingTheException = "Daniel";
throw new LocalizedException(new ErrorBundle("theCauseOfThisException",
new String[]{userCausingTheException}));
}
}
This example shows how to use qualified message providers, instead of searching through all available providers and how to use i18n for messages stored in databases. For the sake of the example, we will create an in memory database holding the i18n messages using HSQLDB.
public class QualifiedJdbcExample {
public static void main(String[] args) throws Exception {
/////////////////////////////////////////////////////
// Prepare example
/////////////////////////////////////////////////////
// Set up in-memory data for the sake of the example
prepareTables();
/////////////////////////////////////////////////////
// Example of initialization
/////////////////////////////////////////////////////
// We can initialize JDBC message provider using a properties file
Properties props = new Properties();
props.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("i18n-jdbc.properties"));
MessageManager.addMessageProvider("messages", new JdbcMessageProvider(props));
// We can also initialize JDBC message provider by providing connection (or DataSource)
Connection conn = getNewConnection();
MessageManager.addMessageProvider("errors", new JdbcMessageProvider(conn, "errors", "id", "language"));
conn.close();
/////////////////////////////////////////////////////
// Example of usage
/////////////////////////////////////////////////////
// Simulate the locale of the current user in a multi-user environment
// such as a web application
Locale currentUsersLocale = new Locale("sv"); // Assume Swedish
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
// Get i18n text qualifying the message source (i.e. the MessageProvider) to use; messages
TextBundle textBundle = new TextBundle("messages", "enterFirstName");
System.out.println(textBundle.getText(currentUsersLocale) + ":");
String firstName = reader.readLine();
textBundle = new TextBundle("messages", "enterLastName");
System.out.println(textBundle.getText(currentUsersLocale) + ":");
String lastName = reader.readLine();
validateNames(firstName, lastName);
}
catch(LocalizedRuntimeException lrex) {
// Retrieve the detailed localized error message
ErrorBundle errorMessage = lrex.getErrorMessage();
// Print summary and details using the current users locale
System.out.println("-- " + errorMessage.getSummary(currentUsersLocale) + " --");
System.out.println(errorMessage.getDetails(currentUsersLocale));
}
}
private static void validateNames(String firstname, String lastname) {
if(firstname.equals(lastname))
throw new LocalizedRuntimeException(new ErrorBundle("errors", "identicalNames"));
}
///////////////////////////////////////////////////////////////////////
// Utility methods for the example
///////////////////////////////////////////////////////////////////////
/**
* Create connection to in-memory HSQLDB database
* @return
* @throws ClassNotFoundException
* @throws SQLException
*/
private static Connection getNewConnection() throws ClassNotFoundException, SQLException {
Class.forName("org.hsqldb.jdbcDriver"); // Load HSQLDB database driver
return DriverManager.getConnection("jdbc:hsqldb:.", "sa", ""); // Connect to in-memory database
}
/**
* Create tables and insert messages
*/
private static void prepareTables() throws ClassNotFoundException, SQLException {
Connection conn = getNewConnection();
Statement stmt = conn.createStatement();
stmt.execute(
"CREATE TABLE messages ( " +
" 'id' VARCHAR(30), " +
" 'language' VARCHAR(2), " +
" 'text' VARCHAR(100)" +
")");
stmt.execute("INSERT INTO messages VALUES ('enterFirstName', 'en', 'Please enter your first name')");
stmt.execute("INSERT INTO messages VALUES ('enterLastName', 'en', 'Please enter your last name')");
stmt.execute("INSERT INTO messages VALUES ('enterFirstName', 'sv', 'Vänligen ange ditt förnamn')");
stmt.execute("INSERT INTO messages VALUES ('enterLastName', 'sv', 'Vänligen ange ditt efternamn')");
stmt.execute(
"CREATE TABLE errors ( " +
" 'id' VARCHAR(30), " +
" 'language' VARCHAR(2), " +
" 'summary' VARCHAR(100), " +
" 'details' VARCHAR(100) " +
")");
stmt.execute("INSERT INTO errors VALUES (" +
" 'identicalNames', 'en', " +
" 'Error! Identical names.', 'You entered the same name as both first name and last name'" +
")");
stmt.execute("INSERT INTO errors VALUES (" +
" 'identicalNames', 'sv', " +
" 'Fel! Identiska namn.', 'Du angav samma namn som både förnamn och efternamn'" +
")");
stmt.close();
conn.close();
}
}