Spring Boot - Internationalization

国际化是一个使您的应用程序适应不同语言和区域而无需对源代码进行工程更改的过程。用它来说，国际化是对本地化的准备。

在本章中，我们将详细了解如何在Spring Boot中实现国际化。

Dependencies

我们需要Spring Boot Starter Web和Spring Boot Starter Thymeleaf依赖来在Spring Boot中开发Web应用程序。

Maven

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

Gradle

compile('org.springframework.boot:spring-boot-starter-web')
compile group: 'org.springframework.boot', name: 'spring-boot-starter-thymeleaf'

LocaleResolver

我们需要确定应用程序的默认Locale。我们需要在Spring Boot应用程序中添加LocaleResolver bean。

@Bean
public LocaleResolver localeResolver() {
   SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
   sessionLocaleResolver.setDefaultLocale(Locale.US);
   return sessionLocaleResolver;
}

LocaleChangeInterceptor

LocaleChangeInterceptor用于根据添加到请求的语言参数的值更改新的Locale。

@Bean
public LocaleChangeInterceptor localeChangeInterceptor() {
   LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
   localeChangeInterceptor.setParamName("language");
   return localeChangeInterceptor;
}

为了起到这种作用，我们需要将LocaleChangeInterceptor添加到应用程序的注册表拦截器中。配置类应扩展WebMvcConfigurerAdapter类并覆盖addInterceptors（）方法。

@Override
public void addInterceptors(InterceptorRegistry registry) {
   registry.addInterceptor(localeChangeInterceptor());
}

消息来源

默认情况下，Spring Boot应用程序从类路径下的src/main/resources文件夹中获取消息源。缺省语言环境消息文件名应为message.properties ，每个语言环境的文件应命名为messages_XX.properties 。 “XX”表示区域代码。

应将所有消息属性用作密钥对值。如果在语言环境中找不到任何属性，则应用程序将使用messages.properties文件中的默认属性。

默认的messages.properties如下所示 -

welcome.text=Hi Welcome to Everyone

法语message_fr.properties如下所示 -

welcome.text=Salut Bienvenue à tous

Note - 消息源文件应保存为“UTF-8”文件格式。

HTML文件

在HTML文件中，使用语法#{key}显示属性文件中的消息。

<h1 th:text = "#{welcome.text}"></h1>

完整的代码如下

Maven - 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/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.iowiki</groupId>
   <artifactId>demo</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <packaging>jar</packaging>
   <name>demo</name>
   <description>Demo project for Spring Boot</description>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>1.5.8.RELEASE</version>
      <relativePath />
   </parent>
   <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
      <java.version>1.8</java.version>
   </properties>
   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-thymeleaf</artifactId>
      </dependency>
   </dependencies>
   <build>
      <plugins>
         <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
         </plugin>
      </plugins>
   </build>
</project>

Gradle - build.gradle

buildscript {
   ext {
      springBootVersion = '1.5.8.RELEASE'
   }
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
   }
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
group = 'com.iowiki'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
   mavenCentral()
}
dependencies {
   compile('org.springframework.boot:spring-boot-starter-web')
   compile group: 'org.springframework.boot', name: 'spring-boot-starter-thymeleaf'
   testCompile('org.springframework.boot:spring-boot-starter-test')
}

主要的Spring Boot应用程序类文件如下 -

package com.iowiki.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
   public static void main(String[] args) {
      SpringApplication.run(DemoApplication.class, args);
   }
}

控制器类文件如下 -

package com.iowiki.demo.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class ViewController {
   @RequestMapping("/locale")
   public String locale() {
      return "locale";
   }
}

配置类支持国际化

package com.iowiki.demo;
import java.util.Locale;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;
@Configuration
public class Internationalization extends WebMvcConfigurerAdapter {
   @Bean
   public LocaleResolver localeResolver() {
      SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
      sessionLocaleResolver.setDefaultLocale(Locale.US);
      return sessionLocaleResolver;
   }
   @Bean
   public LocaleChangeInterceptor localeChangeInterceptor() {
      LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
      localeChangeInterceptor.setParamName("language");
      return localeChangeInterceptor;
   }
   @Override
   public void addInterceptors(InterceptorRegistry registry) {
      registry.addInterceptor(localeChangeInterceptor());
   }
}

消息源 - messages.properties如下所示 -

welcome.text = Hi Welcome to Everyone

消息源 - message_fr.properties如下所示 -

welcome.text = Salut Bienvenue à tous

HTML文件locale.html应该放在类路径的templates目录下，如图所示 -

<!DOCTYPE html>
<html>
   <head>
      <meta charset = "ISO-8859-1"/>
      <title>Internationalization</title>
   </head>
   <body>
      <h1 th:text = "#{welcome.text}"></h1>
   </body>
</html>

您可以创建可执行的JAR文件，并使用以下Maven或Gradle命令运行Spring引导应用程序 -

对于Maven，请使用以下命令 -

mvn clean install

在“BUILD SUCCESS”之后，您可以在目标目录下找到JAR文件。

对于Gradle，请使用以下命令 -

gradle clean build

在“BUILD SUCCESSFUL”之后，您可以在build/libs目录下找到JAR文件。

现在，使用如下所示的命令运行JAR文件 -

java –jar <JARFILE>

您会发现应用程序已在Tomcat端口8080上启动。

现在在Web浏览器中点击URL http://localhost:8080/locale ，您可以看到以下输出 -

URL http://localhost:8080/locale?language=fr将为您提供如下所示的输出 -

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Spring Beans & Dependency Injection

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构建RESTful Web服务(Building RESTful Web Services)

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Spring Boot - Rest Template

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Spring Boot - Thymeleaf

构建RESTful Web服务(Building RESTful Web Services)

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