如何在安卓中使用ImageAdapter将存储在特定文件夹中的图片从SD卡上传到GridView？

Question

我正在尝试从特定文件夹获取图像并将其显示在网格视图中。 但是我得到了一个空的imagelist值，导致程序强制关闭。 我成功获取了文件夹路径，但是获取不到fileList。

File[] imagelist = root.listFiles(new FilenameFilter(){  
            @Override  
            public boolean accept(File dir, String name)  
            {  
                return ((name.endsWith(".jpg"))||(name.endsWith(".png")));
            }  
        }); 

我得到的listFiles是null，它没有进入循环中。请问有人能帮忙吗？

public class IleanaOffline extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.pics);
    GridView grid=(GridView)findViewById(R.id.gridView1);
    File root = new File(Environment.getExternalStorageDirectory()
            + File.separator + "Indian Actress" + File.separator + "Ileana" + File.separator);
    File[] imagelist = root.listFiles(new FilenameFilter(){  
        @Override  
        public boolean accept(File dir, String name)  
        {  
            return ((name.endsWith(".jpg"))||(name.endsWith(".png")));
        }  
    });  
        String[] mFiles = new String[imagelist.length];  

        for(int i= 0 ; i< imagelist.length; i++)  
        {  
            mFiles[i] = imagelist[i].getAbsolutePath();  
        }  
        Uri[] mUrls = new Uri[mFiles.length];  

        for(int i=0; i < mFiles.length; i++)  
        {  
            mUrls[i] = Uri.parse(mFiles[i]);     
        }     

    grid.setAdapter(new CustomAdapterOffline(mUrls,this));
}

}

有人能建议我需要做哪些更改吗？谢谢。

- priya madhuri

---

你是否在 imagelist 数组中获取文件路径？ - ρяσѕρєя K

我已经获取到文件夹路径，但没有获取到图像列表路径。 - priya madhuri

在执行代码的下一部分之前，请放置以下条件if(root.exists() && root.isDirectory()) {make log here if dir exist}以检查SD卡上是否存在目录。 - ρяσѕρєя K

我已经使用 if(root.isDirectory()){} 进行了检查，但它跳过了那一行。 - priya madhuri

如果跳过 isDirectory，意味着在 SDCARD 上不存在文件夹路径，请手动检查 SDCARD 上的文件夹路径。 - ρяσѕρєя K

我明白了，我给出的路径不同了。 - priya madhuri

Answer 1

    enter code here

public class AndroidCustomGalleryActivity extends Activity {
    private int count;
    private Bitmap[] thumbnails;
    private boolean[] thumbnailsselection;
    private String[] arrPath;
    private ImageAdapter imageAdapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        final String[] columns = { MediaStore.Images.Media.DATA, MediaStore.Images.Media._ID };
        final String orderBy = MediaStore.Images.Media._ID;
        Cursor imagecursor = managedQuery(
                MediaStore.Images.Media.EXTERNAL_CONTENT_URI, columns, null,
                null, orderBy);
        int image_column_index = imagecursor.getColumnIndex(MediaStore.Images.Media._ID);
        this.count = imagecursor.getCount();
        this.thumbnails = new Bitmap[this.count];
        this.arrPath = new String[this.count];
        this.thumbnailsselection = new boolean[this.count];
        for (int i = 0; i < this.count; i++) {
            imagecursor.moveToPosition(i);
            int id = imagecursor.getInt(image_column_index);
            int dataColumnIndex = imagecursor.getColumnIndex(MediaStore.Images.Media.DATA);
            thumbnails[i] = MediaStore.Images.Thumbnails.getThumbnail(
                    getApplicationContext().getContentResolver(), id,
                    MediaStore.Images.Thumbnails.MICRO_KIND, null);
            arrPath[i]= imagecursor.getString(dataColumnIndex);
        }
        GridView imagegrid = (GridView) findViewById(R.id.PhoneImageGrid);
        imageAdapter = new ImageAdapter();
        imagegrid.setAdapter(imageAdapter);
        imagecursor.close();

        final Button selectBtn = (Button) findViewById(R.id.HideBtn);
        selectBtn.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub
                final int len = thumbnailsselection.length;
                int cnt = 0;
                String selectImages = "";
                for (int i =0; i<len; i++)
                {
                    if (thumbnailsselection[i]){
                        cnt++;
                        selectImages = selectImages + arrPath[i] + "|";
                    }
                }
                if (cnt == 0){
                    Toast.makeText(getApplicationContext(),
                            "Please select at least one image",
                            Toast.LENGTH_LONG).show();
                } else {
                    Toast.makeText(getApplicationContext(),
                            "You've selected Total " + cnt + " image(s).",
                            Toast.LENGTH_LONG).show();
                    Log.d("SelectedImages", selectImages);
                }
                if (cnt > 1){


                }
            }
        });
    }

    public class ImageAdapter extends BaseAdapter {
        private LayoutInflater mInflater;

        public ImageAdapter() {
            mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        }

        public int getCount() {
            return count;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            if (convertView == null) {
                holder = new ViewHolder();
                convertView = mInflater.inflate(
                        R.layout.galleryitem, null);
                holder.imageview = (ImageView) convertView.findViewById(R.id.thumbImage);
                holder.checkbox = (CheckBox) convertView.findViewById(R.id.itemCheckBox);

                convertView.setTag(holder);
            }
            else {
                holder = (ViewHolder) convertView.getTag();
            }
            holder.checkbox.setId(position);
            holder.imageview.setId(position);
            holder.checkbox.setOnClickListener(new OnClickListener() {

                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    CheckBox cb = (CheckBox) v;
                    int id = cb.getId();
                    if (thumbnailsselection[id]){
                        cb.setChecked(false);
                        thumbnailsselection[id] = false;
                    } else {
                        cb.setChecked(true);
                        thumbnailsselection[id] = true;
                    }
                }
            });
            holder.imageview.setOnClickListener(new OnClickListener() {

                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    int id = v.getId();
                    Intent intent = new Intent();
                    intent.setAction(Intent.ACTION_VIEW);
                    intent.setDataAndType(Uri.parse("file://" + arrPath[id]), "image/*");
                    startActivity(intent);
                }
            });
            holder.imageview.setImageBitmap(thumbnails[position]);
            holder.checkbox.setChecked(thumbnailsselection[position]);
            holder.id = position;
            return convertView;
        }
    }
    class ViewHolder {
        ImageView imageview;
        CheckBox checkbox;
        int id;
    }}





    enter code here

Xml main



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

    <Button
        android:id="@+id/HideBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:minWidth="200px"
        android:text="Hide" />

    <GridView android:id="@+id/PhoneImageGrid"
        android:layout_width="fill_parent" android:layout_height="fill_parent"
        android:numColumns="auto_fit" android:verticalSpacing="10dp"
        android:horizontalSpacing="10dp" android:columnWidth="90dp"
        android:stretchMode="columnWidth" android:gravity="center"
        android:layout_above="@id/HideBtn" />

    <Button
        android:id="@+id/UnHideBtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:minWidth="200px"
        android:text="UnHide" />

</RelativeLayout>


    enter code here

layout 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent">
    <ImageView android:id="@+id/thumbImage" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_centerInParent="true" />
    <CheckBox android:id="@+id/itemCheckBox" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignParentRight="true"
        android:layout_alignParentTop="true" />
</RelativeLayout>

- user2354694

Answer 2

使用下面的代码片段从特定文件夹的SD卡中获取图像

private List<String> ReadSDCardImages() {
               ArrayList<String> fileList= new ArrayList<String>();
               fileList.clear();
               f = new File(Environment.getExternalStorageDirectory()
                               .getAbsolutePath() + "/yourfolderName");

               files = f.listFiles(new FilenameFilter() {
                       @Override
                       public boolean accept(File dir, String name) {
                               return ((name.endsWith(".jpg")) || (name.endsWith(".png")));
                       }
               });

               for (int i = 0; i < files.length; i++) {
                       File file = files[i];
                       fileList.add(file.getPath());
               }
               return fileList;
       }

在从文件夹中获取所有图像后，将数组列表传递给ImageAdapter。希望这对您有所帮助。

- Amol Sawant