我正在为我的Android应用使用Firebase。我在firebase的Storage部分上传了一些图像，并在listview中显示。现在，当我点击recyclerview的特定图像时，我想转到下一个活动并显示我在下一个活动的imageview中点击的图像。如何检索特定图像？请帮忙。
我在firebase的存储空间中创建了一个照片文件夹，所有图像都存储在该文件夹中。
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
public static final String ANONYMOUS = "anonymous";
public static final int DEFAULT_MSG_LENGTH_LIMIT = 1000;
public static final String FRIENDLY_MSG_LENGTH_KEY = "friendly_msg_length";
public static final int RC_SIGN_IN = 1;
private static final int RC_PHOTO_PICKER = 2;
private ListView mMessageListView;
private MessageAdapter mMessageAdapter;
private ProgressBar mProgressBar;
private ImageButton mPhotoPickerButton;
private EditText mMessageEditText;
private Button mSendButton;
private String mUsername;
// Firebase instance variables
private FirebaseDatabase mFirebaseDatabase;
private DatabaseReference mMessagesDatabaseReference;
private ChildEventListener mChildEventListener;
private FirebaseAuth mFirebaseAuth;
private FirebaseAuth.AuthStateListener mAuthStateListener;
private FirebaseStorage mFirebaseStorage;
private StorageReference mChatPhotosStorageReference;
private FirebaseRemoteConfig mFirebaseRemoteConfig;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mUsername = ANONYMOUS;
// Initialize Firebase components
mFirebaseDatabase = FirebaseDatabase.getInstance();
mFirebaseAuth = FirebaseAuth.getInstance();
mFirebaseStorage = FirebaseStorage.getInstance();
mFirebaseRemoteConfig = FirebaseRemoteConfig.getInstance();
mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("messages");
mChatPhotosStorageReference = mFirebaseStorage.getReference().child("photos");
// Initialize references to views
mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
mMessageListView = (ListView) findViewById(R.id.messageListView);
mPhotoPickerButton = (ImageButton) findViewById(R.id.photoPickerButton);
mMessageEditText = (EditText) findViewById(R.id.messageEditText);
mSendButton = (Button) findViewById(R.id.sendButton);
// Initialize message ListView and its adapter
List<FriendlyMessage> friendlyMessages = new ArrayList<>();
mMessageAdapter = new MessageAdapter(this, R.layout.item_message, friendlyMessages);
mMessageListView.setAdapter(mMessageAdapter);
// Initialize progress bar
mProgressBar.setVisibility(ProgressBar.INVISIBLE);
// ImagePickerButton shows an image picker to upload a image for a message
mPhotoPickerButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, "Complete action using"), RC_PHOTO_PICKER);
}
});
// Enable Send button when there's text to send
mMessageEditText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
if (charSequence.toString().trim().length() > 0) {
mSendButton.setEnabled(true);
} else {
mSendButton.setEnabled(false);
}
}
@Override
public void afterTextChanged(Editable editable) {
}
});
mMessageEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(DEFAULT_MSG_LENGTH_LIMIT)});
// Send button sends a message and clears the EditText
mSendButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
FriendlyMessage friendlyMessage = new FriendlyMessage(mMessageEditText.getText().toString(), mUsername, null);
mMessagesDatabaseReference.push().setValue(friendlyMessage);
// Clear input box
mMessageEditText.setText("");
}
});
mAuthStateListener = new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
// User is signed in
onSignedInInitialize(user.getDisplayName());
} else {
// User is signed out
onSignedOutCleanup();
startActivityForResult(
AuthUI.getInstance()
.createSignInIntentBuilder()
.setIsSmartLockEnabled(false)
.setProviders(
AuthUI.EMAIL_PROVIDER,
AuthUI.GOOGLE_PROVIDER)
.build(),
RC_SIGN_IN);
}
}
};
// Create Remote Config Setting to enable developer mode.
// Fetching configs from the server is normally limited to 5 requests per hour.
// Enabling developer mode allows many more requests to be made per hour, so developers
// can test different config values during development.
FirebaseRemoteConfigSettings configSettings = new FirebaseRemoteConfigSettings.Builder()
.setDeveloperModeEnabled(BuildConfig.DEBUG)
.build();
mFirebaseRemoteConfig.setConfigSettings(configSettings);
// Define default config values. Defaults are used when fetched config values are not
// available. Eg: if an error occurred fetching values from the server.
Map<String, Object> defaultConfigMap = new HashMap<>();
defaultConfigMap.put(FRIENDLY_MSG_LENGTH_KEY, DEFAULT_MSG_LENGTH_LIMIT);
mFirebaseRemoteConfig.setDefaults(defaultConfigMap);
fetchConfig();
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RC_SIGN_IN) {
if (resultCode == RESULT_OK) {
// Sign-in succeeded, set up the UI
Toast.makeText(this, "Signed in!", Toast.LENGTH_SHORT).show();
} else if (resultCode == RESULT_CANCELED) {
// Sign in was canceled by the user, finish the activity
Toast.makeText(this, "Sign in canceled", Toast.LENGTH_SHORT).show();
finish();
}
} else if (requestCode == RC_PHOTO_PICKER && resultCode == RESULT_OK) {
Uri selectedImageUri = data.getData();
// Get a reference to store file at chat_photos/<FILENAME>
StorageReference photoRef = mChatPhotosStorageReference.child(selectedImageUri.getLastPathSegment());
// Upload file to Firebase Storage
photoRef.putFile(selectedImageUri)
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
// When the image has successfully uploaded, we get its download URL
Uri downloadUrl = taskSnapshot.getDownloadUrl();
// Set the download URL to the message box, so that the user can send it to the database
FriendlyMessage friendlyMessage = new FriendlyMessage(null, mUsername, downloadUrl.toString());
mMessagesDatabaseReference.push().setValue(friendlyMessage);
}
});
}
}
@Override
protected void onResume() {
super.onResume();
mFirebaseAuth.addAuthStateListener(mAuthStateListener);
}
@Override
protected void onPause() {
super.onPause();
if (mAuthStateListener != null) {
mFirebaseAuth.removeAuthStateListener(mAuthStateListener);
}
mMessageAdapter.clear();
detachDatabaseReadListener();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.sign_out_menu:
AuthUI.getInstance().signOut(this);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void onSignedInInitialize(String username) {
mUsername = username;
attachDatabaseReadListener();
}
private void onSignedOutCleanup() {
mUsername = ANONYMOUS;
mMessageAdapter.clear();
detachDatabaseReadListener();
}
private void attachDatabaseReadListener() {
if (mChildEventListener == null) {
mChildEventListener = new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
FriendlyMessage friendlyMessage = dataSnapshot.getValue(FriendlyMessage.class);
mMessageAdapter.add(friendlyMessage);
}
public void onChildChanged(DataSnapshot dataSnapshot, String s) {}
public void onChildRemoved(DataSnapshot dataSnapshot) {}
public void onChildMoved(DataSnapshot dataSnapshot, String s) {}
public void onCancelled(DatabaseError databaseError) {}
};
mMessagesDatabaseReference.addChildEventListener(mChildEventListener);
}
}
private void detachDatabaseReadListener() {
if (mChildEventListener != null) {
mMessagesDatabaseReference.removeEventListener(mChildEventListener);
mChildEventListener = null;
}
}
// Fetch the config to determine the allowed length of messages.
public void fetchConfig() {
long cacheExpiration = 3600; // 1 hour in seconds
// If developer mode is enabled reduce cacheExpiration to 0 so that each fetch goes to the
// server. This should not be used in release builds.
if (mFirebaseRemoteConfig.getInfo().getConfigSettings().isDeveloperModeEnabled()) {
cacheExpiration = 0;
}
mFirebaseRemoteConfig.fetch(cacheExpiration)
.addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
// Make the fetched config available
// via FirebaseRemoteConfig get<type> calls, e.g., getLong, getString.
mFirebaseRemoteConfig.activateFetched();
// Update the EditText length limit with
// the newly retrieved values from Remote Config.
applyRetrievedLengthLimit();
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
// An error occurred when fetching the config.
Log.w(TAG, "Error fetching config", e);
// Update the EditText length limit with
// the newly retrieved values from Remote Config.
applyRetrievedLengthLimit();
}
});
}
/**
* Apply retrieved length limit to edit text field. This result may be fresh from the server or it may be from
* cached values.
*/
private void applyRetrievedLengthLimit() {
Long friendly_msg_length = mFirebaseRemoteConfig.getLong(FRIENDLY_MSG_LENGTH_KEY);
mMessageEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(friendly_msg_length.intValue())});
Log.d(TAG, FRIENDLY_MSG_LENGTH_KEY + " = " + friendly_msg_length);
}
}
答案 0 :(得分：0)
为recycleview实现onclick侦听器，并将intent图像URL传递给新活动，如下所示
intent.putExtra("IMAGE_URL", "url of the image");
startActivity(intent);
使用以下代码获取第二个活动的URL
String url = getIntent().getStringExtra("IMAGE_URL");
答案 1 :(得分：0)
上传图片时，Firebase会创建下载网址。 从您的代码中可以清楚地看到，您拥有Firebase创建的图像下载URL。
即使您没有下载URL，也可以使用
获取storageReferenceObj.getDownloadUrl();
为了在ImageView中加载该图像，您可以使用Picasso库。
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
将URL替换为您的下载URL并指定图片视图。但首先将此行添加到Gradle文件中以包含Picasso库。
compile 'com.squareup.picasso:picasso:2.5.2'