使用dropwizard(6)-国际化-easy-i18n

Myth丶恋晨 2022-06-03 23:18 207阅读 0赞

![dropwizard-hat.png][]  
![i8n-v2.png][]

# 前言 #

Dropwizard官方文档并没有提供国际化的模块，所以只能自己加。Spring的MessageResource用的很顺手，所以copy过来。

作者：@Ryan-Miao  
本文为作者原创，转载请注明出处：[http://www.cnblogs.com/woshimrf/p/dropwizard-i18n.html][http_www.cnblogs.com_woshimrf_p_dropwizard-i18n.html]

# Easy i18n #

在整合Dropwizard的时候，多语言貌似只能通过jdk自带的ResourceBundle拿数据。其实也就够了，但在开发过程中发现需要缓存，需要解析占位符等。代码越写越多，显然不是仅仅一个调用就完事的。写的差不多的时候突然觉得和spring context里的message source结构类似。于是，放弃维护已经开始变的复杂的逻辑，直接使用spring。

但选取dropwizard的时候就是摒弃了spring，再拿过来也不好玩了。干脆，抽取Spring context项目的MessageResource相关代码，重写封装了一个library: [https://github.com/Ryan-Miao/easy-i18n][https_github.com_Ryan-Miao_easy-i18n], 欢迎star。

[easy-i18n][https_github.com_Ryan-Miao_easy-i18n]还是和在Spring项目中相同。

首先，引入依赖，由于github项目的library已经有仓库去维护了，就没费心思放到maven和jcenter了，直接从github上拉取。类库地址为：

<repositories>
        <repository>
            <id>jitpack.io</id>
            <url>https://jitpack.io</url>
        </repository>
    </repositories>

引入

<dependency>
        <groupId>com.github.Ryan-Miao</groupId>
        <artifactId>easy-i18n</artifactId>
        <version>1.0</version>
    </dependency>

## 简单使用 ##

### \#情形一 只有一个Resource Bundle ###

在resources下新建`i18n/messages.properties`以及`i18n/messages_zh_CN.properties`. demo位置：[l4dropwizard][]

然后，调用方法如下：

@Test
    public void testI18n(){
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.addBasenames("i18n/messages");
        messageSource.setDefaultEncoding("UTF-8");
    
        String index = messageSource.getMessage("index", null, Locale.US);
        System.out.println(index);
    }

### \#情形二 我有多个Resource Bundle ###

实际项目中，由于产品分类，有时候需要创建多个Resource Bundle，这时候也简单，只要创建多个`ResourceBundleMessageSource`来读取翻译即可。

public void testI18n2(){
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.addBasenames("i18n/messages");
        messageSource.setDefaultEncoding("UTF-8");
    
        String index = messageSource.getMessage("index", null, Locale.US);
        System.out.println(index);
    
        ResourceBundleMessageSource messageSource2 = new ResourceBundleMessageSource();
        messageSource2.addBasenames("i18n/messages2");
        messageSource2.setDefaultEncoding("UTF-8");
    
        String second = messageSource2.getMessage("second", null, Locale.US);
        System.out.println(second);
    }

### \#情形三 我有多个Resource Bundle但读取翻译的时候我想一起 ###

有时候，想要读取翻译，可能翻译文件在不同的Resource Bundle，但我指向用一个接口去调用。这时候，做法时候在这几个Resource Bundle的里面添加命名空间，即key要在这几个Resource Bundle里唯一，而不仅仅是本文件唯一。

然后，

public void testI18n2(){
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        messageSource.addBasenames("i18n/messages", "i18n/messages2");
        messageSource.setDefaultEncoding("UTF-8");
    
        String index = messageSource.getMessage("index", null, Locale.US);
        System.out.println(index);
    }

这种做法，会一次从两个Resource Bundle里寻找翻译，找到即返回。因此，如果有相同的key，将导致只有第一个生效。

### \#情形4 ###

没有了，你翻译要那么复杂吗。

更多用法，参考测试类：[ResourceBundleMessageSourceTest][]

# Demo source #

[https://github.com/Ryan-Miao/l4dropwizard][https_github.com_Ryan-Miao_l4dropwizard]

本文是基于[dropwizard入门][dropwizard]之上的演进。

确保依赖都是最新的，或者自行解决版本冲突，比如jackson不同版本之间的类有所不同。

## 引入easy-i18n ##

repository url

<repositories>
        <repository>
            <id>jitpack.io</id>
            <url>https://jitpack.io</url>
        </repository>
    </repositories>

引入

<dependency>
        <groupId>com.github.Ryan-Miao</groupId>
        <artifactId>easy-i18n</artifactId>
        <version>1.0</version>
    </dependency>

## 添加Resource Bundle ##

在[resources][]下新增文件夹`i18n`, 依次添加几个Resource Bundle。具体做法是，在文件夹`i18n`右键 -> `new` \-> `Resource Bundle`, 然后选择想要支持的语言。比如美国`en_US`，简体中文`zh_CN`。

## 新建MessageService ##

创建一个Util来处理翻译功能。  
com.test.domain.service.IMessageService

package com.test.domain.service;
    
    import java.text.MessageFormat;
    import java.util.List;
    import java.util.Locale;
    
    /** * The Message translation service * Created by Ryan Miao on 11/23/17. */
    public interface IMessageService { 
    
        /** * Get translation by message key. * * @param key The message key in the properties * @return the translated message */
        String getMessage(String key, Locale locale);
    
        /** * Get translation by message key and compose it with variables. * Note that the variable would be injected by {@link MessageFormat} * * @param key The message key in the properties * @param args The variables to inject into the message. * @return the translated message. */
        String getMessage(String key, List<String> args, Locale locale);
    }

实现类`com.test.domain.service.impl.MessageService`

package com.test.domain.service.impl;
    
    import com.miao.easyi18n.support.ResourceBundleMessageSource;
    import com.test.domain.service.IMessageService;
    
    import javax.inject.Inject;
    import javax.inject.Singleton;
    import java.util.List;
    import java.util.Locale;
    
    /** * Created by Ryan Miao on 11/23/17. */
    @Singleton
    public class MessageService implements IMessageService{ 
    
        private final ResourceBundleMessageSource messageSource;
    
        @Inject
        public MessageService(ResourceBundleMessageSource messageSource) {
            this.messageSource = messageSource;
        }
    
        @Override
        public String getMessage(String key, Locale locale) {
            return messageSource.getMessage(key, null, locale);
        }
    
        @Override
        public String getMessage(String key, List<String> args, Locale locale) {
            return messageSource.getMessage(key, args.toArray(), locale);
        }
    }

## 在IoC中提供ResourceBundleMessageSource ##

由于`ResourceBundleMessageSource`是公共组件，需要单独提取出来，并使用单例模式创建。关于IoC的配置，参阅[dropwizard中添加DI][dropwizard_DI]

在`ConfigurationModule`中：

package com.test.domain.ioc.module;
    
    import com.miao.easyi18n.support.ResourceBundleMessageSource;
    import com.test.configuration.HelloWorldConfiguration;
    import dagger.Module;
    import dagger.Provides;
    
    import javax.inject.Singleton;
    
    /** * Created by Ryan Miao on 11/20/17. */
    @Module
    public class ConfigurationModule { 
        private final HelloWorldConfiguration configuration;
    
        public ConfigurationModule(HelloWorldConfiguration configuration) {
            this.configuration = configuration;
        }
    
    
        @Provides
        @Singleton
        HelloWorldConfiguration helloWorldConfiguration(){
            return configuration;
        }
    
        @Singleton
        @Provides
        ResourceBundleMessageSource resourceBundleMessageSource(){
            ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
            messageSource.addBasenames("i18n/messages", "i18n/messages2", "i18n/otherGroup");
            messageSource.setDefaultEncoding("UTF-8");
    
            return messageSource;
        }
    }

这里，关于Resource Bundle的位置没有单独提出来，后面可以放到`HelloWorldConfiguration`，提到配置文件中。

## 测试 ##

在dagger中，接口和实现类的绑定只能通过手动声明。因此，绑定`IMessageService`

@Singleton
    @Provides
    IMessageService messageService(MessageService messageService){
        return messageService;
    }

创建测试Resource， `com.test.domain.resource.LocalResource`

package com.test.domain.resource;
    
    import com.codahale.metrics.annotation.Timed;
    import com.google.common.collect.ImmutableMap;
    import com.test.domain.entiry.GithubUser;
    import com.test.domain.service.IMessageService;
    import io.swagger.annotations.Api;
    import io.swagger.annotations.ApiOperation;
    import io.swagger.annotations.ApiResponse;
    import io.swagger.annotations.ApiResponses;
    
    import javax.inject.Inject;
    import javax.validation.Valid;
    import javax.validation.constraints.NotNull;
    import javax.validation.constraints.Pattern;
    import javax.ws.rs.GET;
    import javax.ws.rs.HeaderParam;
    import javax.ws.rs.Path;
    import javax.ws.rs.PathParam;
    import javax.ws.rs.Produces;
    import javax.ws.rs.core.MediaType;
    import java.util.Locale;
    import java.util.Map;
    
    /** * Test localization * Created by Ryan Miao on 11/23/17. */
    @Api("/local")
    @Path("/local")
    @Produces(MediaType.APPLICATION_JSON)
    public class LocalResource { 
    
        private final IMessageService messageService;
    
        @Inject
        public LocalResource(IMessageService messageService) {
            this.messageService = messageService;
        }
    
        @GET
        @Timed
        @Path("/{key}")
        @ApiOperation(value = "Get github user profile.", notes = "There should be the note.")
        @ApiResponses({
                @ApiResponse(code = 401, message = "Valid credentials are required to access this resource."),
                @ApiResponse(code = 400, message = "Params not valid."),
                @ApiResponse(code = 500, message = "Something wrong from the server."),
                @ApiResponse(code = 200, message = "Success.", response = GithubUser.class)
        })
        public Map<String, String> getIndex(
                @PathParam("key") final String index,
                @HeaderParam("Accept-Language") @Valid
                @NotNull(message = "cannot be null.")
                @Pattern(regexp = "([a-z]{2}-[A-Z]{2})", message = "pattern should like zh-CN, en-US.")
                final String language
        ) {
            final Locale locale = Locale.forLanguageTag(language);
            final String message = messageService.getMessage(index, locale);
            return ImmutableMap.of(index, message);
        }
    }

结果  
![local-cn.png_raw_true][]  
![local-en-US.png_raw_true][]

[dropwizard-hat.png]: /images/20220604/4e363a9de5284ef8949e26d277efbcd2.png
[i8n-v2.png]: /images/20220604/21572a21e0694d358ce33084704d24fc.png
[http_www.cnblogs.com_woshimrf_p_dropwizard-i18n.html]: http://www.cnblogs.com/woshimrf/p/dropwizard-i18n.html
[https_github.com_Ryan-Miao_easy-i18n]: https://github.com/Ryan-Miao/easy-i18n
[l4dropwizard]: https://github.com/Ryan-Miao/l4dropwizard/blob/master/src/main/resources/i18n/messages.properties
[ResourceBundleMessageSourceTest]: https://github.com/Ryan-Miao/easy-i18n/blob/master/src/test/java/com/miao/easyi18n/support/ResourceBundleMessageSourceTest.java
[https_github.com_Ryan-Miao_l4dropwizard]: https://github.com/Ryan-Miao/l4dropwizard
[dropwizard]: http://www.cnblogs.com/woshimrf/tag/dropwizard/
[resources]: https://github.com/Ryan-Miao/l4dropwizard/tree/master/src/main/resources
[dropwizard_DI]: http://www.cnblogs.com/woshimrf/p/dropwizard-with-dagger2-example.html
[local-cn.png_raw_true]: /images/20220604/3b45b5006f424c73975ff54f33a93191.png
[local-en-US.png_raw_true]: /images/20220604/7d53f23e24f348f386bc03f9a4f80fd1.png