Localizer

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>example</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <packaging>jar</packaging>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.8</version>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                    <additionalConfig>
                        <file>
                            <name>.settings/org.eclipse.core.resources.prefs</name>
                            <content>
              <![CDATA[
eclipse.preferences.version=1
encoding/<project>=UTF-8
              ]]>
                            </content>
                        </file>
                        <file>
                            <name>.settings/org.eclipse.core.runtime.prefs</name>
                            <content>
              <![CDATA[
eclipse.preferences.version=1
line.separator=\n
              ]]>
                            </content>
                        </file>
                    </additionalConfig>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.jvnet.localizer</groupId>
                <artifactId>maven-localizer-plugin</artifactId>
                <version>1.12</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.jvnet.localizer</groupId>
            <artifactId>localizer</artifactId>
            <version>1.12</version>
        </dependency>
    </dependencies>
</project>

Resources.java

package com.example;

import java.util.Locale;

import org.jvnet.localizer.LocaleProvider;

public class Resources {

    public static void main(String[] args) throws Exception {
        final WebRequestLocaleProvider localeProvider = new WebRequestLocaleProvider();
        LocaleProvider.setProvider(localeProvider);

        for (int i = 0; i < 100; i++) {
            final int num = i;
            new Thread(new Runnable() {
                @Override
                public void run() {
                    Locale locale = num % 2 == 0 ? Locale.JAPAN : Locale.US;
                    localeProvider.alloc(locale);
                    System.out.println(locale + ":" + Messages.hello("world"));
                    localeProvider.release();
                }
            }).start();
        }

        Thread.sleep(1000);
    }

    static class WebRequestLocaleProvider extends LocaleProvider {

        private ThreadLocal<Locale> locales = new ThreadLocal<Locale>();

        public void alloc(Locale locale) {
            locales.set(locale);
        }

        public void release() {
            locales.remove();
        }

        @Override
        public Locale get() {
            return locales.get();
        }
    }
}