在 Android 裝置上使用 Cloud Storage 上傳檔案

Cloud Storage for Firebase 可讓您輕鬆快速地將檔案上傳到 已提供 Cloud Storage 個值區 並由 Firebase 管理

上傳檔案

如要上傳檔案到 Cloud Storage,請先建立指向 檔案的完整路徑,包括檔案名稱。

Kotlin+KTX

// 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()putStream() 方法,即可上傳檔案 至 Cloud Storage

您無法上傳任何參照 Cloud Storage 個值區。參照項目必須指向子網址。

從記憶體中的資料上傳

putBytes() 方法是將檔案上傳至 Cloud Storage 最簡單的方式。putBytes() 會擷取 byte[] 並傳回 UploadTask,用於管理及監控上傳狀態。

Kotlin+KTX

// 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[],因此應用程式必須保留整個 檔案內容建議使用 putStream()putFile(),即可減少記憶體。

從串流上傳

putStream() 是最適合用來上傳 將檔案複製到 Cloud StorageputStream() 會接受 InputStream 並傳回 可用來管理及監控上傳狀態的 UploadTask

Kotlin+KTX

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

您可以上傳裝置上的本機檔案,例如 相機使用 putFile() 方法。putFile() 會取用 File 並傳回 UploadTask,用於管理及監控上傳狀態。

Kotlin+KTX

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,您可以呼叫 StorageReference 上的 getDownloadUrl() 方法:

Kotlin+KTX

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

您也可以在上傳檔案時加入中繼資料。這項中繼資料包含一般檔案中繼資料屬性,例如 namesize、 和 contentType (通常稱為 MIME 類型)。putFile() 方法 從 File 副檔名自動推論 MIME 類型,但您也可以 請在中繼資料中指定 contentType,覆寫自動偵測的類型。如果 您並未提供 contentType,而 Cloud Storage 無法推斷出 預設副檔名,Cloud Storage 會使用 application/octet-stream。請參閱使用檔案中繼資料 一節,進一步瞭解檔案中繼資料。

Kotlin+KTX

// 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

除了開始上傳之外,您還可以使用 pause()resume()cancel() 方法。暫停及繼續活動 可分別引發 pauseprogress 狀態變更。取消 上傳失敗並傳回錯誤 已取消上傳。

Kotlin+KTX

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來處理成功、失敗、進度或暫停 上傳工作:

監聽器類型 一般用量
OnProgressListener 系統會在資料傳輸過程中定期呼叫這個事件監聽器,並用來填入上傳/下載指標。
OnPausedListener 工作暫停時,系統就會呼叫此事件監聽器。
OnSuccessListener 工作順利完成後,系統就會呼叫此事件監聽器。
OnFailureListener 上傳失敗時,系統就會呼叫此事件監聽器。可能的原因包括網路逾時、授權失敗或是您取消工作。

OnFailureListener 會使用 Exception 例項呼叫。其他事件監聽器會使用 UploadTask.TaskSnapshot 物件呼叫。此物件是事件發生時的工作不可變動的檢視畫面。 UploadTask.TaskSnapshot 包含下列屬性:

屬性 類型 說明
getDownloadUrl String 可用來下載物件的網址。這個網址是可公開檢索的公開網址,可與其他客戶分享。上傳完成後,系統就會填入這個值。
getError Exception 如果工作失敗,這會造成原因為「例外狀況」。
getBytesTransferred long 擷取這個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 透過對 putFile 發出的其他呼叫,可用來繼續這項工作的 URI。
getMetadata StorageMetadata 上傳完成之前,系統會將中繼資料傳送至伺服器。上傳完成後,這是伺服器傳回的中繼資料。
getTask UploadTask 建立這張快照的工作。透過這項工作取消、暫停或繼續上傳作業。
getStorage StorageReference 用來建立 UploadTaskStorageReference

UploadTask 事件監聽器提供簡單又強大的方式進行監控 上傳事件。

Kotlin+KTX

// 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

即使活動生命週期有所變更 (例如 例如簡報或旋轉畫面)。您附加的所有事件監聽器也會保留附加狀態。這可能會導致未預期的結果 。

如要解決這個問題,可以利用活動範圍訂閱事件監聽器 ,在活動停止時自動取消註冊。接著,使用 getActiveUploadTasks 方法 (用於重新啟動活動以取得上傳工作) 仍在執行或最近完成的工作

下例示範了這項做法,並示範如何保存儲存空間 參照路徑。

Kotlin+KTX

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 會擷取位於以下位置及較低位置的所有進行中上傳工作 方便您處理多項工作。

在程序重新啟動時繼續上傳

如果程序關閉,所有進行中的上傳作業將會中斷。 不過,在程序重新啟動後,您就可以繼續執行 與伺服器上傳工作階段這樣不僅能節省時間和頻寬 從檔案開頭開始上傳

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

Kotlin+KTX

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.
        }
    }
});

程序因上傳作業中斷而重新啟動後,請再次呼叫 putFile。但 這次也會傳遞已儲存的 URI

Kotlin+KTX

// 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);

上週的工作階段。如果您嘗試在工作階段到期後恢復工作階段,或工作階段發生錯誤,您會收到失敗的回呼。您有責任確保檔案在上傳後不會變更。

處理錯誤

導致上傳發生錯誤的原因有很多種,包括 本機檔案不存在,或使用者無權上傳 指定要上傳的檔案如要進一步瞭解錯誤,請參閱 處理錯誤 一節。

完整範例

含有進度監控和錯誤處理機制的完整上傳示例 如下所示:

Kotlin+KTX

// 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,我們接著來學習如何 下載 出發地:Cloud Storage