在 Android 裝置上使用 Cloud Storage 上傳檔案

Cloud Storage for Firebase 可讓您快速輕鬆地將檔案上傳至 Firebase 提供及管理的 Cloud Storage bucket。

上傳檔案

如要將檔案上傳至 Cloud Storage，請先建立檔案完整路徑 (包括檔案名稱) 的參照。

Kotlin

// Create a storage reference from our app
val storageRef = storage.reference

// Create a reference to "mountains.jpg"
val mountainsRef = storageRef.child("mountains.jpg")

// Create a reference to 'images/mountains.jpg'
val mountainImagesRef = storageRef.child("images/mountains.jpg")

// While the file names are the same, the references point to different files
mountainsRef.name == mountainImagesRef.name // true
mountainsRef.path == mountainImagesRef.path // false

Java

// Create a storage reference from our app
StorageReference storageRef = storage.getReference();

// Create a reference to "mountains.jpg"
StorageReference mountainsRef = storageRef.child("mountains.jpg");

// Create a reference to 'images/mountains.jpg'
StorageReference mountainImagesRef = storageRef.child("images/mountains.jpg");

// While the file names are the same, the references point to different files
mountainsRef.getName().equals(mountainImagesRef.getName());    // true
mountainsRef.getPath().equals(mountainImagesRef.getPath());    // false

建立適當的參照後，請呼叫 putBytes()、putFile() 或 putStream() 方法，將檔案上傳至 Cloud Storage。

上傳資料時，不得參照 Cloud Storage bucket 的根目錄。參照必須指向子網址。

從記憶體中的資料上傳

putBytes() 方法是將檔案上傳至 Cloud Storage 的最簡單方式。putBytes() 會採用 byte[] 並傳回 UploadTask，可用於管理及監控上傳狀態。

Kotlin

// Get the data from an ImageView as bytes
imageView.isDrawingCacheEnabled = true
imageView.buildDrawingCache()
val bitmap = (imageView.drawable as BitmapDrawable).bitmap
val baos = ByteArrayOutputStream()
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos)
val data = baos.toByteArray()

var uploadTask = mountainsRef.putBytes(data)
uploadTask.addOnFailureListener {
    // Handle unsuccessful uploads
}.addOnSuccessListener { taskSnapshot ->
    // taskSnapshot.metadata contains file metadata such as size, content-type, etc.
    // ...
}

Java

// Get the data from an ImageView as bytes
imageView.setDrawingCacheEnabled(true);
imageView.buildDrawingCache();
Bitmap bitmap = ((BitmapDrawable) imageView.getDrawable()).getBitmap();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] data = baos.toByteArray();

UploadTask uploadTask = mountainsRef.putBytes(data);
uploadTask.addOnFailureListener(new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception exception) {
        // Handle unsuccessful uploads
    }
}).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
        // taskSnapshot.getMetadata() contains file metadata such as size, content-type, etc.
        // ...
    }
});

由於 putBytes() 接受 byte[]，因此應用程式必須一次將檔案的完整內容保留在記憶體中。建議使用 putStream() 或 putFile()，減少記憶體用量。

從串流上傳

putStream() 方法是將檔案上傳至 Cloud Storage 最通用的方式。putStream() 接受 InputStream 並傳回 UploadTask，可用於管理及監控上傳狀態。

Kotlin

val stream = FileInputStream(File("path/to/images/rivers.jpg"))

uploadTask = mountainsRef.putStream(stream)
uploadTask.addOnFailureListener {
    // Handle unsuccessful uploads
}.addOnSuccessListener { taskSnapshot ->
    // taskSnapshot.metadata contains file metadata such as size, content-type, etc.
    // ...
}

Java

InputStream stream = new FileInputStream(new File("path/to/images/rivers.jpg"));

uploadTask = mountainsRef.putStream(stream);
uploadTask.addOnFailureListener(new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception exception) {
        // Handle unsuccessful uploads
    }
}).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
        // taskSnapshot.getMetadata() contains file metadata such as size, content-type, etc.
        // ...
    }
});

從本機檔案上傳

您可以使用 putFile() 方法上傳裝置上的本機檔案，例如相機中的相片和影片。putFile() 會採用 File 並傳回 UploadTask，您可以使用該物件管理及監控上傳狀態。

Kotlin

var file = Uri.fromFile(File("path/to/images/rivers.jpg"))
val riversRef = storageRef.child("images/${file.lastPathSegment}")
uploadTask = riversRef.putFile(file)

// Register observers to listen for when the download is done or if it fails
uploadTask.addOnFailureListener {
    // Handle unsuccessful uploads
}.addOnSuccessListener { taskSnapshot ->
    // taskSnapshot.metadata contains file metadata such as size, content-type, etc.
    // ...
}

Java

Uri file = Uri.fromFile(new File("path/to/images/rivers.jpg"));
StorageReference riversRef = storageRef.child("images/"+file.getLastPathSegment());
uploadTask = riversRef.putFile(file);

// Register observers to listen for when the download is done or if it fails
uploadTask.addOnFailureListener(new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception exception) {
        // Handle unsuccessful uploads
    }
}).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
        // taskSnapshot.getMetadata() contains file metadata such as size, content-type, etc.
        // ...
    }
});

取得下載網址

上傳檔案後，您可以對 StorageReference 呼叫 getDownloadUrl() 方法，取得下載檔案的網址：

Kotlin

val ref = storageRef.child("images/mountains.jpg")
uploadTask = ref.putFile(file)

val urlTask = uploadTask.continueWithTask { task ->
    if (!task.isSuccessful) {
        task.exception?.let {
            throw it
        }
    }
    ref.downloadUrl
}.addOnCompleteListener { task ->
    if (task.isSuccessful) {
        val downloadUri = task.result
    } else {
        // Handle failures
        // ...
    }
}

Java

final StorageReference ref = storageRef.child("images/mountains.jpg");
uploadTask = ref.putFile(file);

Task<Uri> urlTask = uploadTask.continueWithTask(new Continuation<UploadTask.TaskSnapshot, Task<Uri>>() {
    @Override
    public Task<Uri> then(@NonNull Task<UploadTask.TaskSnapshot> task) throws Exception {
        if (!task.isSuccessful()) {
            throw task.getException();
        }

        // Continue with the task to get the download URL
        return ref.getDownloadUrl();
    }
}).addOnCompleteListener(new OnCompleteListener<Uri>() {
    @Override
    public void onComplete(@NonNull Task<Uri> task) {
        if (task.isSuccessful()) {
            Uri downloadUri = task.getResult();
        } else {
            // Handle failures
            // ...
        }
    }
});

新增檔案中繼資料

上傳檔案時，也可以加入中繼資料。 這項中繼資料包含一般檔案中繼資料屬性，例如 name、size 和 contentType (通常稱為 MIME 類型)。putFile() 方法會自動從 File 擴充功能推斷 MIME 類型，但您可以在中繼資料中指定 contentType，覆寫自動偵測到的類型。如果您未提供 contentType，且 Cloud Storage 無法從副檔名推斷預設值，Cloud Storage 會使用 application/octet-stream。如要進一步瞭解檔案中繼資料，請參閱「使用檔案中繼資料」一節。

Kotlin

// Create file metadata including the content type
var metadata = storageMetadata {
    contentType = "image/jpg"
}

// Upload the file and metadata
uploadTask = storageRef.child("images/mountains.jpg").putFile(file, metadata)

Java

// Create file metadata including the content type
StorageMetadata metadata = new StorageMetadata.Builder()
        .setContentType("image/jpg")
        .build();

// Upload the file and metadata
uploadTask = storageRef.child("images/mountains.jpg").putFile(file, metadata);

管理上傳項目

除了開始上傳，您也可以使用 pause()、resume() 和 cancel() 方法暫停、繼續及取消上傳。暫停和繼續事件會分別引發 pause 和 progress 狀態變更。取消上傳會導致上傳失敗，並顯示上傳已取消的錯誤。

Kotlin

uploadTask = storageRef.child("images/mountains.jpg").putFile(file)

// Pause the upload
uploadTask.pause()

// Resume the upload
uploadTask.resume()

// Cancel the upload
uploadTask.cancel()

Java

uploadTask = storageRef.child("images/mountains.jpg").putFile(file);

// Pause the upload
uploadTask.pause();

// Resume the upload
uploadTask.resume();

// Cancel the upload
uploadTask.cancel();

監控上傳進度

您可以新增事件監聽器，處理上傳任務的成功、失敗、進度或暫停：

監聽器類型 常見用途
OnProgressListener 系統會在傳輸資料時定期呼叫這個事件監聽器，可用於填入上傳/下載指標。
OnPausedListener 每當工作暫停時，系統就會呼叫這個事件監聽器。
OnSuccessListener 工作成功完成時，系統會呼叫這個事件監聽器。
OnFailureListener 只要上傳失敗，系統就會呼叫這個事件監聽器。這可能是因為網路逾時、授權失敗，或您取消了工作。

系統會使用 Exception 例項呼叫 OnFailureListener。其他事件監聽器則會使用 UploadTask.TaskSnapshot 物件呼叫。這個物件是事件發生時工作的不可變檢視。UploadTask.TaskSnapshot 包含下列屬性：

屬性 類型 說明
getDownloadUrl String 可用於下載物件的網址。這是一個公開且無法猜測的網址，可與其他用戶端共用。上傳完成後，系統會填入這個值。
getError Exception 如果工作失敗，這裡會顯示原因 (以例外狀況的形式)。
getBytesTransferred long 擷取這張快照時，已傳輸的位元組總數。
getTotalByteCount long 預計上傳的位元組總數。
getUploadSessionUri String 這個 URI 可用於透過另一個 putFile 呼叫繼續執行這項工作。
getMetadata StorageMetadata 在上傳完成前，這是傳送至伺服器的中繼資料。上傳完成後，伺服器會傳回這項中繼資料。
getTask UploadTask 建立這張快照的工作。使用這項工作取消、暫停或繼續上傳。
getStorage StorageReference 用於建立 UploadTask 的 StorageReference。

UploadTask 事件監聽器提供簡單而強大的方式，可監控上傳事件。

Kotlin

// Observe state change events such as progress, pause, and resume
// You'll need to import com.google.firebase.storage.component1 and
// com.google.firebase.storage.component2
uploadTask.addOnProgressListener { (bytesTransferred, totalByteCount) ->
    val progress = (100.0 * bytesTransferred) / totalByteCount
    Log.d(TAG, "Upload is $progress% done")
}.addOnPausedListener {
    Log.d(TAG, "Upload is paused")
}

Java

// Observe state change events such as progress, pause, and resume
uploadTask.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
        double progress = (100.0 * taskSnapshot.getBytesTransferred()) / taskSnapshot.getTotalByteCount();
        Log.d(TAG, "Upload is " + progress + "% done");
    }
}).addOnPausedListener(new OnPausedListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onPaused(UploadTask.TaskSnapshot taskSnapshot) {
        Log.d(TAG, "Upload is paused");
    }
});

處理活動生命週期變更

即使活動生命週期發生變化 (例如顯示對話方塊或旋轉螢幕)，上傳作業仍會在背景繼續進行。任何附加的事件監聽器也會保持附加狀態。如果在活動停止後呼叫，可能會導致非預期的結果。

如要解決這個問題，請使用 Activity 範圍訂閱事件監聽器，以便在 Activity 停止時自動取消註冊。接著，在活動重新啟動時使用 getActiveUploadTasks 方法，取得仍在執行或最近完成的上傳任務。

以下範例示範這項操作，並說明如何保留所用的儲存空間參考路徑。

Kotlin

override fun onSaveInstanceState(outState: Bundle) {
    super.onSaveInstanceState(outState)

    // If there's an upload in progress, save the reference so you can query it later
    outState.putString("reference", storageRef.toString())
}

override fun onRestoreInstanceState(savedInstanceState: Bundle) {
    super.onRestoreInstanceState(savedInstanceState)

    // If there was an upload in progress, get its reference and create a new StorageReference
    val stringRef = savedInstanceState.getString("reference") ?: return

    storageRef = Firebase.storage.getReferenceFromUrl(stringRef)

    // Find all UploadTasks under this StorageReference (in this example, there should be one)

    val tasks = storageRef.activeUploadTasks

    if (tasks.size > 0) {
        // Get the task monitoring the upload
        val task = tasks[0]

        // Add new listeners to the task using an Activity scope
        task.addOnSuccessListener(this) {
            // Success!
            // ...
        }
    }
}

Java

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    // If there's an upload in progress, save the reference so you can query it later
    if (mStorageRef != null) {
        outState.putString("reference", mStorageRef.toString());
    }
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);

    // If there was an upload in progress, get its reference and create a new StorageReference
    final String stringRef = savedInstanceState.getString("reference");
    if (stringRef == null) {
        return;
    }
    mStorageRef = FirebaseStorage.getInstance().getReferenceFromUrl(stringRef);

    // Find all UploadTasks under this StorageReference (in this example, there should be one)
    List<UploadTask> tasks = mStorageRef.getActiveUploadTasks();
    if (tasks.size() > 0) {
        // Get the task monitoring the upload
        UploadTask task = tasks.get(0);

        // Add new listeners to the task using an Activity scope
        task.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
            @Override
            public void onSuccess(UploadTask.TaskSnapshot state) {
                // Success!
                // ...
            }
        });
    }
}

getActiveUploadTasks 會擷取指定參照位置及以下的所有有效上傳工作，因此您可能需要處理多項工作。

在程序重新啟動後繼續上傳

如果程序關閉，所有進行中的上傳作業都會中斷。 不過，只要與伺服器恢復上傳工作階段，您就可以在程序重新啟動後繼續上傳。這樣就不必從檔案開頭開始上傳，可節省時間和頻寬。

如要這麼做，請透過 putFile 開始上傳。在產生的 StorageTask 上，呼叫 getUploadSessionUri，並將產生的值儲存在永久儲存空間 (例如 SharedPreferences)。

Kotlin

uploadTask = storageRef.putFile(localFile)
uploadTask.addOnProgressListener { taskSnapshot ->
    sessionUri = taskSnapshot.uploadSessionUri
    if (sessionUri != null && !saved) {
        saved = true
        // A persisted session has begun with the server.
        // Save this to persistent storage in case the process dies.
    }
}

Java

uploadTask = mStorageRef.putFile(localFile);
uploadTask.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
        Uri sessionUri = taskSnapshot.getUploadSessionUri();
        if (sessionUri != null && !mSaved) {
            mSaved = true;
            // A persisted session has begun with the server.
            // Save this to persistent storage in case the process dies.
        }
    }
});

上傳作業中斷後，程序重新啟動時，請再次呼叫 putFile。但這次也會傳遞已儲存的 URI。

Kotlin

// resume the upload task from where it left off when the process died.
// to do this, pass the sessionUri as the last parameter
uploadTask = storageRef.putFile(
    localFile,
    storageMetadata { },
    sessionUri,
)

Java

//resume the upload task from where it left off when the process died.
//to do this, pass the sessionUri as the last parameter
uploadTask = mStorageRef.putFile(localFile,
        new StorageMetadata.Builder().build(), sessionUri);

工作階段會持續一週。如果您嘗試在工作階段過期或發生錯誤後繼續工作階段，系統會傳回失敗回呼。您有責任確保檔案在上傳期間未發生變更。

錯誤處理機制

上傳時發生錯誤的原因有很多，包括本機檔案不存在，或使用者沒有上傳所需檔案的權限。如要進一步瞭解錯誤，請參閱說明文件的「處理錯誤」一節。

完整範例

以下是上傳作業的完整範例，包含進度監控和錯誤處理：

Kotlin

// File or Blob
file = Uri.fromFile(File("path/to/mountains.jpg"))

// Create the file metadata
metadata = storageMetadata {
    contentType = "image/jpeg"
}

// Upload file and metadata to the path 'images/mountains.jpg'
uploadTask = storageRef.child("images/${file.lastPathSegment}").putFile(file, metadata)

// Listen for state changes, errors, and completion of the upload.
// You'll need to import com.google.firebase.storage.component1 and
// com.google.firebase.storage.component2
uploadTask.addOnProgressListener { (bytesTransferred, totalByteCount) ->
    val progress = (100.0 * bytesTransferred) / totalByteCount
    Log.d(TAG, "Upload is $progress% done")
}.addOnPausedListener {
    Log.d(TAG, "Upload is paused")
}.addOnFailureListener {
    // Handle unsuccessful uploads
}.addOnSuccessListener {
    // Handle successful uploads on complete
    // ...
}

Java

// File or Blob
file = Uri.fromFile(new File("path/to/mountains.jpg"));

// Create the file metadata
metadata = new StorageMetadata.Builder()
        .setContentType("image/jpeg")
        .build();

// Upload file and metadata to the path 'images/mountains.jpg'
uploadTask = storageRef.child("images/"+file.getLastPathSegment()).putFile(file, metadata);

// Listen for state changes, errors, and completion of the upload.
uploadTask.addOnProgressListener(new OnProgressListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onProgress(UploadTask.TaskSnapshot taskSnapshot) {
        double progress = (100.0 * taskSnapshot.getBytesTransferred()) / taskSnapshot.getTotalByteCount();
        Log.d(TAG, "Upload is " + progress + "% done");
    }
}).addOnPausedListener(new OnPausedListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onPaused(UploadTask.TaskSnapshot taskSnapshot) {
        Log.d(TAG, "Upload is paused");
    }
}).addOnFailureListener(new OnFailureListener() {
    @Override
    public void onFailure(@NonNull Exception exception) {
        // Handle unsuccessful uploads
    }
}).addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
    @Override
    public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
        // Handle successful uploads on complete
        // ...
    }
});

上傳檔案後，接著來瞭解如何從 Cloud Storage 下載檔案。