在 Android 上使用 ML Kit 翻譯文字

你可以使用 ML Kit 翻譯不同語言的文字。ML Kit 目前支援 59 種語言的互譯功能。

事前準備

  1. 如果您尚未將 Firebase 新增至 Android 專案，請先新增。
  2. 將 ML Kit Android 程式庫的依附元件新增至模組 (應用程式層級) Gradle 檔案 (通常為 app/build.gradle)： 
    apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'

dependencies {
  // ...

  implementation 'com.google.firebase:firebase-ml-natural-language:22.0.0'
  implementation 'com.google.firebase:firebase-ml-natural-language-translate-model:20.0.8'
}

翻譯一串文字

如要翻譯兩種語言之間的字串，請按照下列步驟操作：

  1. 建立 FirebaseTranslator 物件，並設定來源和目標語言：

    Java 

    // Create an English-German translator:
FirebaseTranslatorOptions options =
        new FirebaseTranslatorOptions.Builder()
                .setSourceLanguage(FirebaseTranslateLanguage.EN)
                .setTargetLanguage(FirebaseTranslateLanguage.DE)
                .build();
final FirebaseTranslator englishGermanTranslator =
        FirebaseNaturalLanguage.getInstance().getTranslator(options);

    Kotlin 

    // Create an English-German translator:
val options = FirebaseTranslatorOptions.Builder()
        .setSourceLanguage(FirebaseTranslateLanguage.EN)
        .setTargetLanguage(FirebaseTranslateLanguage.DE)
        .build()
val englishGermanTranslator = FirebaseNaturalLanguage.getInstance().getTranslator(options)

    如果您不知道輸入文字的語言，可以先使用語言辨識 API。(但請確保裝置上不會同時保留過多語言模型)。

  2. 確認裝置已下載必要的翻譯模型。 請等到模型可供使用後，再呼叫 translate()。

    Java 

    FirebaseModelDownloadConditions conditions = new FirebaseModelDownloadConditions.Builder()
    .requireWifi()
    .build();
englishGermanTranslator.downloadModelIfNeeded(conditions)
      .addOnSuccessListener(
          new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void v) {
              // Model downloaded successfully. Okay to start translating.
              // (Set a flag, unhide the translation UI, etc.)
            }
          })
      .addOnFailureListener(
          new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
              // Model couldn’t be downloaded or other internal error.
              // ...
            }
          });

    Kotlin 

    englishGermanTranslator.downloadModelIfNeeded()
        .addOnSuccessListener {
            // Model downloaded successfully. Okay to start translating.
            // (Set a flag, unhide the translation UI, etc.)
        }
        .addOnFailureListener { exception ->
            // Model couldn’t be downloaded or other internal error.
            // ...
        }

    語言模型約 30 MB，因此請勿不必要地下載，且除非使用者另有指定，否則請僅透過 Wi-Fi 下載。您也應刪除不需要的模型。請參閱「明確管理翻譯模型」。

  3. 確認模型已下載後，請將來源語言的文字字串傳遞至 translate()：

    Java 

    englishGermanTranslator.translate(text)
      .addOnSuccessListener(
          new OnSuccessListener<String>() {
            @Override
            public void onSuccess(@NonNull String translatedText) {
              // Translation successful.
            }
          })
      .addOnFailureListener(
          new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
              // Error.
              // ...
            }
          });

    Kotlin 

    englishGermanTranslator.translate(text)
        .addOnSuccessListener { translatedText ->
            // Translation successful.
        }
        .addOnFailureListener { exception ->
             // Error.
             // ...
        }

    系統會將譯文 (以您設定的目標語言呈現) 傳遞至成功事件監聽器。

明確管理翻譯模型

如上所述使用 Translation API 時，ML Kit 會視需要自動將特定語言的翻譯模型下載至裝置。您也可以使用 ML Kit 的翻譯模型管理 API，明確管理要在裝置上使用的翻譯模型。如果您想預先下載模型，或從裝置中刪除不需要的模型，這項功能就非常實用。

Java 

FirebaseModelManager modelManager = FirebaseModelManager.getInstance();

// Get translation models stored on the device.
modelManager.getDownloadedModels(FirebaseTranslateRemoteModel.class)
        .addOnSuccessListener(new OnSuccessListener<Set<FirebaseTranslateRemoteModel>>() {
            @Override
            public void onSuccess(Set<FirebaseTranslateRemoteModel> models) {
                // ...
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                // Error.
            }
        });

// Delete the German model if it's on the device.
FirebaseTranslateRemoteModel deModel =
        new FirebaseTranslateRemoteModel.Builder(FirebaseTranslateLanguage.DE).build();
modelManager.deleteDownloadedModel(deModel)
        .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void v) {
                // Model deleted.
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                // Error.
            }
        });

// Download the French model.
FirebaseTranslateRemoteModel frModel =
        new FirebaseTranslateRemoteModel.Builder(FirebaseTranslateLanguage.FR).build();
FirebaseModelDownloadConditions conditions = new FirebaseModelDownloadConditions.Builder()
        .requireWifi()
        .build();
modelManager.download(frModel, conditions)
        .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void v) {
                // Model downloaded.
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                // Error.
            }
        });

Kotlin 

val modelManager = FirebaseModelManager.getInstance()

// Get translation models stored on the device.
modelManager.getDownloadedModels(FirebaseTranslateRemoteModel::class.java)
    .addOnSuccessListener { models ->
        // ...
    }
    .addOnFailureListener {
        // Error.
    }

// Delete the German model if it's on the device.
val deModel = FirebaseTranslateRemoteModel.Builder(FirebaseTranslateLanguage.DE).build()
modelManager.deleteDownloadedModel(deModel)
    .addOnSuccessListener {
        // Model deleted.
    }
    .addOnFailureListener {
        // Error.
    }

// Download the French model.
val frModel = FirebaseTranslateRemoteModel.Builder(FirebaseTranslateLanguage.FR).build()
val conditions = FirebaseModelDownloadConditions.Builder()
    .requireWifi()
    .build()
modelManager.download(frModel, conditions)
    .addOnSuccessListener {
        // Model downloaded.
    }
    .addOnFailureListener {
        // Error.
    }