Question

我对android编程很新。我想设计一个应用程序，它将在手机的图库中下载图像，图像已经存储在firebase中。图像正在下载并正在imageview中设置但不幸的是我无法在手机库中找到它。我还在清单文件中添加了写入外部存储权限。这是我的DownloadActivity.java：

 package com.example.android.myapplication;

/**
 * Created by Krishnendu on 25-03-2017.
 */

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.firebase.storage.FileDownloadTask;
import com.google.firebase.storage.FirebaseStorage;
import com.google.firebase.storage.StorageReference;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import static android.R.attr.src;

public class DownloadActivity extends RootActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        final ImageView imageView = (ImageView)findViewById(R.id.image);
        View btnDownloadByteArray = findViewById(R.id.btn_download_byte);
        btnDownloadByteArray.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FirebaseStorage storage = FirebaseStorage.getInstance();
                StorageReference storageRef = storage.getReferenceFromUrl("gs://test1-a7e81.appspot.com").child("as.jpg");
                final long ONE_MEGABYTE = 1024 * 1024;

                //download file as a byte array
                storageRef.getBytes(ONE_MEGABYTE).addOnSuccessListener(new OnSuccessListener<byte[]>() {
                    @Override
                    public void onSuccess(byte[] bytes) {
                        Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
                        imageView.setImageBitmap(bitmap);
                        showToast("Download successful!");
                    }
                });
            }
        });

        View btnDownloadAsFile = findViewById(R.id.btn_download_file);
        btnDownloadAsFile.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FirebaseStorage storage = FirebaseStorage.getInstance();
                final StorageReference storageRef = storage.getReferenceFromUrl("gs://test1-a7e81.appspot.com").child("as.jpg");

                //get download file url
                storageRef.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                    @Override
                    public void onSuccess(Uri uri) {
                        Log.i("Main", "File uri: " + uri.toString());
                    }
                });

                //download the file
                try {
                    showProgressDialog("Download File", "Downloading File...");
                    final File localFile = File.createTempFile("images","jpg");


                    storageRef.getFile(localFile).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {

                        @Override
                        public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
                            Bitmap bitmap = BitmapFactory.decodeFile(localFile.getAbsolutePath());
                            imageView.setImageBitmap(bitmap);
                            dismissProgressDialog();
                            showToast("Download successful!");
                            Log.i("path",localFile.getPath());
                            Log.i("parent",localFile.getParent());

                        }
                    }).addOnFailureListener(new OnFailureListener() {
                        @Override
                        public void onFailure(@NonNull Exception exception) {
                            dismissProgressDialog();
                            showToast("Download Failed!");
                        }
                    });
                } catch (Exception e ) {
                    e.printStackTrace();
                    Log.e("Main", "IOE Exception");
                }
            }
        });
    }
}

这是我的RootActivity.java文件：`

    package com.example.android.myapplication;

import android.app.ProgressDialog;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.widget.Toast;

public class RootActivity extends AppCompatActivity {

    private ProgressDialog progressDialog;

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

    }

    protected void showProgressDialog(String title, String msg) {
        progressDialog = ProgressDialog.show(this, title, msg, true);
    }

    protected void showToast(String msg) {
        Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
    }

    protected void dismissProgressDialog() {
        progressDialog.dismiss();
    }
}

这是我的activity_main.xml文件：`

 <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="495dp">

        <Button
            android:id="@+id/btn_download_byte"
            android:text="Download as byte Array"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/btn_download_file"
            android:text="Download as File"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

        <ImageView
            android:id="@+id/image"
            android:layout_width="200dp"
            android:layout_height="200dp"
            android:layout_gravity="center"
            android:layout_centerHorizontal="true"
            android:contentDescription="@null" />

    </LinearLayout>

这是我的清单文件：

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android.myapplication">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.WRITE_INTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".DownloadActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

您无法在图库中存储图像文件，因为图库应用程序不是存储位置，而只是一个显示设备上所有图像文件的应用程序。要了解设备上的图像文件，Gallery应用程序会查询MediaStore。 MediaStore将索引您设备上的图像文件。

如果您创建新文件，则应通知MediaStore。否则，Gallery应用程序将不会“看到”它。

当图像存储在firebase中时，如何在图库中保存图像？

1 个答案: