Android 图库显示来自 SD 卡的图像

Question

这是我的图库程序，里面显示的是静态文件的内容，如何修改这个程序来显示SD卡里的照片，如果没有照片或者SD卡提示

 package DisplayViewsExample.com;

import android.app.Activity;
import android.os.Bundle;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;




   public class DisplayViewsExampleActivity extends Activity {

 Integer[] imageIDs = {
            R.drawable.sample_1,
            R.drawable.sample_2,
            R.drawable.sample_3

    };

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Gallery gallery = (Gallery) findViewById(R.id.gallery1);

    gallery.setAdapter(new ImageAdapter(this));        
    gallery.setOnItemClickListener(new OnItemClickListener() 
    {
        public void onItemClick(AdapterView parent, 
        View v, int position, long id) 
        {                
    /*        Toast.makeText(getBaseContext(), 
                    "pic" + (position + 1) + " selected", 
                    Toast.LENGTH_SHORT).show();*/
            ImageView imageView = (ImageView) findViewById(R.id.image1);                
            imageView.setImageResource(imageIDs[position]);

        }
    });

}
public class ImageAdapter extends BaseAdapter 
{
    private Context context;
    private int itemBackground;

    public ImageAdapter(Context c) 
    {
        context = c;
        //---setting the style---
        TypedArray a = obtainStyledAttributes(R.styleable.Gallery1);
        itemBackground = a.getResourceId(
            R.styleable.Gallery1_android_galleryItemBackground, 0);
        a.recycle();                    
    }

    //---returns the number of images---
    public int getCount() {
        return imageIDs.length;
    }

    //---returns the ID of an item--- 
    public Object getItem(int position) {
        return position;
    }            

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

    //---returns an ImageView view---
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView = new ImageView(context);
        imageView.setImageResource(imageIDs[position]);
        imageView.setScaleType(ImageView.ScaleType.FIT_XY);
        imageView.setLayoutParams(new Gallery.LayoutParams(150, 120));
        imageView.setBackgroundResource(itemBackground);
        return imageView;
    }


}    

}

Answer 1

您应该首先在 list 中设置权限:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

然后，编写递归地从 SD 中获取所有图像文件的函数:

final static String[] IMAGE_FORMATS = new String[] {
        ".JPEG", ".GIF", ".PNG", ".BMP"};

public static ArrayList<File> getImageFilesFromSD() {

    File dir = Environment.getExternalStorageDirectory();

    if (dir == null || !dir.exists())
        return null;

    ArrayList<File> images = getImageFilesFromDir(dir);
    return images;

}

private static ArrayList<File> getImageFilesFromDir(File dir) {
    File[] files = dir.listFiles();
    ArrayList<File> result = new ArrayList<File>();
    if (files != null)
        for (File file : files) {
            if (file.isDirectory()) {
                result.addAll(getImageFilesFromDir(file));
            } else {
                final String fileName = file.getName();
                final String fileNameLwr = fileName.toLowerCase();
                // filtering images by extension
                boolean contains = false;
                for (int i = 0; i < IMAGE_FORMATS.length; i++) {
                    final String formatLwr = IMAGE_FORMATS[i].toLowerCase();
                    if (fileNameLwr.endsWith(formatLwr)) {
                        contains = true;
                        break;
                    }
                }
                if (contains) {
                    result.add(file);
                }
            }
        }
    return result;
}

之后在你的列表适配器中:

imageView.setImageURI(Uri.fromFile(file));

其中 file 是 getImageFilesFromSD() 函数返回的 ArrayList 的元素。

祝你好运。