Question

我必须创建一个gridview，它载有来自SDCard上的特定文件夹的图像。该文件夹的路径是“/ sdcard / images /”。我试过这个代码，应用程序加载时间过长，只显示一张图片。

    public class ImAdapterh extends BaseAdapter{

       File dir=new File(Environment.getExternalStorageDirectory(),"/myImages/");

int count=dir.list().length; 

String[] fileNames = dir.list();

 private Context mContext;

    public ImAdapterh(Context c) {
        mContext = c;
    }

    public int getCount() {
        return count;
    }

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

    public long getItemId(int position) {
        return 0;
    }

    // create a new ImageView for each item referenced by the Adapter
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView = null;        


      for(String bitmapFileName : fileNames)
      {
           if (convertView == null) 
           {  // if it's not recycled, initialize some attributes
               imageView = new ImageView(mContext);
               imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
               imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
               imageView.setPadding(8, 8, 8, 8);                   

               Bitmap bmp = BitmapFactory.decodeFile(dir.getPath() + "/" + bitmapFileName);
               System.out.println(dir);
               imageView.setImageBitmap(bmp);  
            }else 
            {
            imageView = (ImageView) convertView;            

            }
    } 
        return imageView;
        }

该应用占用了太多时间，而且只显示了一张图片

这是我的活动课

      public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);        
       GridView gridview = (GridView) findViewById(R.id.gridview);
       gridview.setAdapter(new ImAdapterh(this));}

Answer 1

该文件夹的路径是“/ sdcard / images /".

不，它不是，至少不适用于大多数设备。永远不要在Android中硬编码路径。始终使用Environment.getExternalStorageDirectory()获取外部存储的根目录。

我尝试使用此代码，该应用程序花费了太多时间加载，并且它只显示一个图像。

当然。你在这里所做的事情是非常正确的。

最大的问题是，getView()为ImageView返回的每一行Adapter将每个图片加载到同一个ImageView。据推测，您应该只将一个图像加载到给定行的{{1}}中。

您的下一个最大问题是您正在主应用程序线程上执行磁盘I / O.

Answer 2

从任何特定目录获取图像。使用以下代码

public void searchImageFromSpecificDirectory() {

        String path = null;

        String uri = MediaStore.Images.Media.DATA;
        // if GetImageFromThisDirectory is the name of the directory from which image will be retrieved
        String condition = uri + " like '%/GetImageFromThisDirectory/%'";
        String[] projection = { uri, MediaStore.Images.Media.DATE_ADDED,
                MediaStore.Images.Media.SIZE };
        Vector additionalFiles = null;
        try {
            if (additionalFiles == null) {
                additionalFiles = new Vector<String>();
            }



            Cursor cursor = managedQuery(
                    MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection,
                    condition, null, null);
            if (cursor != null) {

                boolean isDataPresent = cursor.moveToFirst();

                if (isDataPresent) {

                    do {

                        path = cursor.getString(cursor.getColumnIndex(uri));
System.out.println("...path..."+path);
additionalFiles.add(path);
            }while(cursor.moveToNext());
                }
            if (cursor != null) {
                cursor.close();
            }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

如何在SD卡中动态显示文件夹中的图像

2 个答案: