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，請先完成這項操作。
  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 (通常是 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'
}

翻譯一段文字

如何在兩種語言之間翻譯字串：

  1. 建立 FirebaseTranslator 物件，並使用原文和目標語言設定該物件：

    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+KTX 

    // 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，可以先使用語言識別 API。但請注意，不要同時在裝置中儲存太多語言模型。

  2. 確認所需翻譯模型已下載到裝置。 確認模型可用前，請勿呼叫 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+KTX 

    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.
            // ...
        }

    語言模型約為 30 MB，因此除非使用者另有指定，否則請避免不必要的下載，並只使用 Wi-Fi 下載。建議您一併刪除不需要的模型。請參閱「明確管理翻譯模型」。

  3. 確認下載模型後，請將原文語言的字串傳送至 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+KTX 

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

    系統會以您設定的目標語言將翻譯完成的文字傳遞至成功事件監聽器。

明確管理翻譯模型

按照上述方式使用翻譯 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，明確管理要在裝置中使用的翻譯模型。如果您想預先下載模型，或是從裝置刪除不需要的模型，這項功能就能派上用場。

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+KTX 

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.
    }