Cloud Storage for Firebase 可讓您輕鬆快速地下載 從 Cloud Storage 由 Firebase 提供並管理的值區
可建立參照
如要下載檔案，請先 建立 Cloud Storage 參考資料 加入要下載的檔案
您可以在
Cloud Storage 值區，或者您也可以從現有
gs:// 或 https:// 網址；參照 Cloud Storage 中的物件。
Kotlin+KTX
// Create a storage reference from our app
val storageRef = storage.reference
// Create a reference with an initial file path and name
val pathReference = storageRef.child("images/stars.jpg")
// Create a reference to a file from a Google Cloud Storage URI
val gsReference = storage.getReferenceFromUrl("gs://bucket/images/stars.jpg")
// Create a reference from an HTTPS URL
// Note that in the URL, characters are URL escaped!
val httpsReference = storage.getReferenceFromUrl(
"https://firebasestorage.googleapis.com/b/bucket/o/images%20stars.jpg",
)
Java
// Create a storage reference from our app
StorageReference storageRef = storage.getReference();
// Create a reference with an initial file path and name
StorageReference pathReference = storageRef.child("images/stars.jpg");
// Create a reference to a file from a Google Cloud Storage URI
StorageReference gsReference = storage.getReferenceFromUrl("gs://bucket/images/stars.jpg");
// Create a reference from an HTTPS URL
// Note that in the URL, characters are URL escaped!
StorageReference httpsReference = storage.getReferenceFromUrl("https://firebasestorage.googleapis.com/b/bucket/o/images%20stars.jpg");
下載檔案
取得參考資料後，您可以從 Cloud Storage 下載檔案
呼叫 getBytes() 或 getStream()如果偏好下載檔案
但您可以使用 getDownloadUrl() 取得下載網址。
在記憶體中下載
使用 getBytes() 方法將檔案下載到 byte[]。這就是
下載檔案是最簡單的方法，但必須載入
將檔案匯入記憶體如果您要求的檔案超過應用程式可用空間
因此應用程式將當機為防範記憶體問題，getBytes()
需要的最大下載位元組數將大小上限設為其他內容
或其他下載方式。
Kotlin+KTX
var islandRef = storageRef.child("images/island.jpg")
val ONE_MEGABYTE: Long = 1024 * 1024
islandRef.getBytes(ONE_MEGABYTE).addOnSuccessListener {
// Data for "images/island.jpg" is returned, use this as needed
}.addOnFailureListener {
// Handle any errors
}
Java
StorageReference islandRef = storageRef.child("images/island.jpg");
final long ONE_MEGABYTE = 1024 * 1024;
islandRef.getBytes(ONE_MEGABYTE).addOnSuccessListener(new OnSuccessListener<byte[]>() {
@Override
public void onSuccess(byte[] bytes) {
// Data for "images/island.jpg" is returns, use this as needed
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
下載至本機檔案
getFile() 方法會將檔案直接下載到本機裝置。適用情況
使用者希望在離線時存取檔案，或是在
不同的應用程式getFile() 會傳回 DownloadTask，供您用於管理
請依照下載狀態監控下載狀態，並監控下載狀態。
Kotlin+KTX
islandRef = storageRef.child("images/island.jpg")
val localFile = File.createTempFile("images", "jpg")
islandRef.getFile(localFile).addOnSuccessListener {
// Local temp file has been created
}.addOnFailureListener {
// Handle any errors
}
Java
islandRef = storageRef.child("images/island.jpg");
File localFile = File.createTempFile("images", "jpg");
islandRef.getFile(localFile).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
@Override
public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
// Local temp file has been created
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
如要主動管理下載項目，請參閱 詳情請參閱管理下載內容。
透過網址下載資料
如果您已擁有以網址為基礎的下載基礎架構，或是
要分享網址，您可以呼叫
Cloud Storage 參考資料的 getDownloadUrl() 方法。
Kotlin+KTX
storageRef.child("users/me/profile.png").downloadUrl.addOnSuccessListener {
// Got the download URL for 'users/me/profile.png'
}.addOnFailureListener {
// Handle any errors
}
Java
storageRef.child("users/me/profile.png").getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
// Got the download URL for 'users/me/profile.png'
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
使用 FirebaseUI 下載映像檔
FirebaseUI 相當簡單 且可用於實際工作環境的原生行動繫結 樣板程式碼並推廣 Google 最佳做法FirebaseUI 可讓您 輕鬆快速地下載、快取及顯示圖片 整合了 Cloud Storage 滑行。
首先，請將 FirebaseUI 新增至您的 app/build.gradle：
dependencies {
// FirebaseUI Storage only
implementation 'com.firebaseui:firebase-ui-storage:7.2.0'
}
然後您就能直接從 Cloud Storage 將圖片載入 ImageView：
Kotlin+KTX
// Reference to an image file in Cloud Storage
val storageReference = Firebase.storage.reference
// ImageView in your Activity
val imageView = findViewById<ImageView>(R.id.imageView)
// Download directly from StorageReference using Glide
// (See MyAppGlideModule for Loader registration)
Glide.with(context)
.load(storageReference)
.into(imageView)
Java
// Reference to an image file in Cloud Storage
StorageReference storageReference = FirebaseStorage.getInstance().getReference();
// ImageView in your Activity
ImageView imageView = findViewById(R.id.imageView);
// Download directly from StorageReference using Glide
// (See MyAppGlideModule for Loader registration)
Glide.with(context)
.load(storageReference)
.into(imageView);
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)。你附加的所有事件監聽器 仍保持連結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
在活動重新啟動以取得下載時使用 getActiveDownloadTasks 方法
仍在執行或最近完成的工作
下例示範了這個做法，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 a download 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 a download in progress, get its reference and create a new StorageReference
val stringRef = savedInstanceState.getString("reference") ?: return
storageRef = Firebase.storage.getReferenceFromUrl(stringRef)
// Find all DownloadTasks under this StorageReference (in this example, there should be one)
val tasks = storageRef.activeDownloadTasks
if (tasks.size > 0) {
// Get the task monitoring the download
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 a download 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 a download 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 DownloadTasks under this StorageReference (in this example, there should be one)
List<FileDownloadTask> tasks = mStorageRef.getActiveDownloadTasks();
if (tasks.size() > 0) {
// Get the task monitoring the download
FileDownloadTask task = tasks.get(0);
// Add new listeners to the task using an Activity scope
task.addOnSuccessListener(this, new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
@Override
public void onSuccess(FileDownloadTask.TaskSnapshot state) {
// Success!
// ...
}
});
}
}
處理錯誤
下載時可能會發生錯誤的原因有很多，包括 檔案不存在，或使用者沒有存取所需檔案的權限。 如要進一步瞭解錯誤，請前往 處理錯誤 一節。
完整範例
下面是含有錯誤處理的下載完整範例：
Kotlin+KTX
storageRef.child("users/me/profile.png").getBytes(Long.MAX_VALUE).addOnSuccessListener {
// Use the bytes to display the image
}.addOnFailureListener {
// Handle any errors
}
Java
storageRef.child("users/me/profile.png").getBytes(Long.MAX_VALUE).addOnSuccessListener(new OnSuccessListener<byte[]>() {
@Override
public void onSuccess(byte[] bytes) {
// Use the bytes to display the image
}
}).addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception) {
// Handle any errors
}
});
您也可以取得及更新中繼資料 儲存在 Cloud Storage 中的檔案