如何将图像从 URL 保存到内部或外部存储中？

Question

这是我的代码，上面写着no such file or directory。谁能帮我这个？我想将图像从 URL 保存到存储中。

if (imageLoaded) {
    ByteArrayOutputStream bytes = new ByteArrayOutputStream();
    if (imageBitmap == null) {
        Toast.makeText(getActivity(), "Looks like images didn't load.", Toast.LENGTH_SHORT).show();
    } else {
        imageBitmap.compress(Bitmap.CompressFormat.JPEG,100,bytes);
        File directory = null;
        if (Environment.getExternalStorageDirectory().equals(Environment.MEDIA_MOUNTED)) {
            directory = new File(Environment.getExternalStorageDirectory(),"COC");
            if (!directory.isDirectory()) {
                directory.mkdirs();
            }
        }

        File f = new File(directory,ImageName+".jpg");
            try {
                f.createNewFile();
                FileOutputStream fo = null;
                fo = new FileOutputStream(f);
                fo.write(bytes.toByteArray());
                Toast.makeText(getActivity(),"saved",Toast.LENGTH_SHORT).show();
                fo.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Answer 1

您抱怨无法创建文件。但是您尝试在不存在的目录中写入文件。在 mkdirs() 之后，您不会检查目录是否确实已创建。好吧不是。

从 Android 6 开始，您应该在运行时要求用户确认您在清单中请求的权限。

Google 获取运行时权限。

Answer 2

对于这种情况，选择像 Retrofit 这样的网络库会很好。否则，您必须创建一个 HTTP url 连接，将图像下载为位图，然后将其保存到文件中。所有工作都需要在主线程之外完成。所以需要大量的线程池。所以让我们通过改造来解决问题

首先将改造作为依赖项添加到您的应用级 gradle 文件中

compile 'com.squareup.retrofit:retrofit:2.0.0'
compile 'com.squareup.retrofit:converter-gson:2.0.0'

然后创建一个包含图像视图的演示布局文件，在这个图像视图中我们将显示下载的图像

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

<ImageView
    android:id="@+id/imageViewId"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:adjustViewBounds="true"
    android:maxWidth="1420px"
    android:maxHeight="700px"
    android:scaleType="fitCenter" />

</RelativeLayout>

之后让我们创建一个这样的网络 API 接口

public interface RetrofitImageAPI {
@GET("retrofit/images/uploads/android.jpg")
Call<ResponseBody> getImageDetails();
} 

这是使用改造作为 sigleton 模式的好习惯 (see this)

但出于演示目的，我将在一个活动中展示所有内容

public class MainActivity extends AppCompatActivity {

String url = "http://www.delaroystudios.com/";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    Button ButtonArray= (Button) findViewById(R.id.RetrofitImage);

    ButtonArray.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            View VisibleImage = findViewById(R.id.RetrofitImage);
            VisibleImage.setVisibility(View.GONE);
            getRetrofitImage();
        }
    });

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });
}

void getRetrofitImage() {

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(url)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

    RetrofitImageAPI service = retrofit.create(RetrofitImageAPI.class);

    Call<ResponseBody> call = service.getImageDetails();

    call.enqueue(new Callback<ResponseBody>() {
        @Override
        public void onResponse(Response<ResponseBody> response, Retrofit retrofit) {

            try {

                Log.d("onResponse", "Response came from server");

                boolean FileDownloaded = DownloadImage(response.body());

                Log.d("onResponse", "Image is downloaded and saved ? " + FileDownloaded);

            } catch (Exception e) {
                Log.d("onResponse", "There is an error");
                e.printStackTrace();
            }

        }

        @Override
        public void onFailure(Throwable t) {
            Log.d("onFailure", t.toString());
        }
    });
}

private boolean DownloadImage(ResponseBody body) {

    try {
        Log.d("DownloadImage", "Reading and writing file");
        InputStream in = null;
        FileOutputStream out = null;

        try {
            in = body.byteStream();
            out = new FileOutputStream(getExternalFilesDir(null) + File.separator + "Android.jpg");
            int c;

            while ((c = in.read()) != -1) {
                out.write(c);
            }
        }
        catch (IOException e) {
            Log.d("DownloadImage",e.toString());
            return false;
        }
        finally {
            if (in != null) {
                in.close();
            }
            if (out != null) {
                out.close();
            }
        }

        int width, height;

        ImageView image = (ImageView) findViewById(R.id.imageViewId);
        Bitmap bMap = BitmapFactory.decodeFile(getExternalFilesDir(null) + File.separator + "Android.jpg");
        width = 2*bMap.getWidth();
        height = 3*bMap.getHeight();
        Bitmap bMap2 = Bitmap.createScaledBitmap(bMap, width, height, false);
        image.setImageBitmap(bMap2);

        return true;

    } catch (IOException e) {
        Log.d("DownloadImage",e.toString());
        return false;
    }
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item)
  } 
}

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Answer 3

将位图保存到您选择的目录文件的非常简单的代码：

 final File myImageFile = new File(FILE_DIRECTORY, IMAGE_NAME); // Create image file
                    FileOutputStream fos = null;
                    try {
                        fos = new FileOutputStream(myImageFile);
                        IMAGE_BITMAP.compress(Bitmap.CompressFormat.JPEG, 100, fos);

                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {

                        try {
                            fos.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    Log.i("image", "image saved to >>>" + Uri.parse("file://" + myImageFile.toString()).toString());

如果你想使用 volley，那么你可以执行以下操作：

 ImageRequest ir = new ImageRequest(url,
            new Response.Listener<Bitmap>() {
                @Override
                public void onResponse(Bitmap response) {

                    final File myImageFile = new File(fileDirectory, imageName); // Create image file
                    FileOutputStream fos = null;
                    try {
                        fos = new FileOutputStream(myImageFile);
                        response.compress(Bitmap.CompressFormat.JPEG, 100, fos);

                    } catch (IOException e) {
                        e.printStackTrace();
                    } finally {

                        try {
                            fos.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    Log.i("image", "image saved to >>>" + Uri.parse("file://" + myImageFile.toString()).toString());                       downloadedFileUris.add(FileProvider.getUriForFile(ViewReportsActivity.this.getBaseContext(), BuildConfig.APPLICATION_ID + ".provider", myImageFile));

                }
            }, 0, 0, null, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
                   }
    });

Answer 4

使用毕加索：

Picasso.with(mContext)
        .load(ImageUrl)
        .into(new Target() {
            @Override
            public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                try {
                    String root = Environment.getExternalStorageDirectory().toString();
                    File myDir = new File(root + "/yourDirectory");

                    if (!myDir.exists()) {
                        myDir.mkdirs();
                    }

                    String name = new Date().toString() + ".jpg";
                    myDir = new File(myDir, name);
                    FileOutputStream out = new FileOutputStream(myDir);
                    bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out);

                    out.flush();
                    out.close();                        
                } catch(Exception e){
                    // some action
                }
            }

            @Override
            public void onBitmapFailed(Drawable errorDrawable) {
            }

            @Override
            public void onPrepareLoad(Drawable placeHolderDrawable) {
            }
        }
    );