这里我从数据库中获取存储的图片路径。这样我就可以借助路径在gridview中显示图像。但正如我在下面的代码中所示，我正在cursoradapter中加载asynctask。这里的问题是第一次可以在加载所有图像之前花费一些时间。
但是如果用户再向图片库添加一张图片，那么加载所有图片需要花费很多时间，因为我将asynctask保留在 onResume（）中，以使添加的图片也可见。每当用户添加每张图片时也是如此。有人可以建议我一个简单的方法来获得最后添加的图片在gridview中可见，而无需再次加载所有图片。或者在最少的情况下，如果不可能，有人可以帮我实现当前cursoradapter的延迟适配器吗？
public class ImagesScreen extends Activity {
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.images_screen);
gridView = (GridView)findViewById(R.id.gridView1);
String[] from = new String[] { Reminders.MOM_PATHS };
int[] to = new int[] {};
dbCon = new SQLiteConnectClass(ImagesScreen.this);
imageCursorAdapter = new ImageCursorAdapter(ImagesScreen.this, R.layout.griditem, null, from, to);
gridView.setAdapter(imageCursorAdapter);
}
protected void onResume() {
super.onResume();
new GetImages().execute((Object[]) null);
}
private class GetImages extends AsyncTask<Object, Object, Cursor> {
@Override
protected Cursor doInBackground(Object... params) {
return dbCon.getAllImages();
}
@Override
protected void onPostExecute(Cursor result) {
imageAdapter.changeCursor(result);
}
public void addpictures(View view){
// code for adding picture paths to the database by transferring to another activity.
}
}
CustomAdapter类：
public class ImageCursorAdapter extends SimpleCursorAdapter{
private int layout;
private LayoutInflater mLayoutInflater;
private Context mContext;
public ImageAdapter(Context context, int layout, Cursor c,String[] from, int[] to) {
super(context, layout, c, from, to,0);
this.layout = layout;
mLayoutInflater=LayoutInflater.from(context);
mContext = context;
}
public View newView(Context context, Cursor cursor, ViewGroup parent) {
View v = mLayoutInflater.inflate(layout, parent, false);
return v;
}
public void bindView(final View v, final Context context, Cursor c) {
final int id = c.getInt(c.getColumnIndex("id"));
final String imagepath = c.getString(c.getColumnIndex("paths"));
ImageView imageview = (ImageView)v.findViewById(R.id.imageView1);
File imgFile = new File(imagepath);
if(imgFile.exists()){
Bitmap imageBitmap = decodeFile(imgFile);
imageview.setImageBitmap(imageBitmap);
}
}
}
答案 0 :(得分：4)
使用此代码
public class Imagegallery extends Activity implements OnItemClickListener,
OnScrollListener, OnTouchListener {
Button btn;
SQLiteDatabase sampleDB = null;
String SAMPLE_DB_NAME = "hic";
int size = 0;
TextView headertext;
Button cartbtn;
ImageView footer1, footer2, footer3, footer4, footer5;
GridView gridView;
boolean larg = false;
String products;
int j = 1;
int ii = 0;
String imagepath[];
String productname[];
int productid[] = new int[1000];
String productids[] = new String[1000];
int integerprodids[] = new int[1000];
final Context context = this;
String filename2[];
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.currentspecial);
File root = new File(Environment.getExternalStorageDirectory()
+ File.separator + "aiwhic/product" + File.separator);
File[] fileName = root.listFiles();
filename2 = new String[fileName.length];
for (int j = 0; j < fileName.length; j++) {
Uri uri = Uri.fromFile(fileName[j]);
filename2[j] = fileName[j].getAbsolutePath();
Log.e("file", filename2[j]);
}
gridView = (GridView) findViewById(R.id.gridView1);
gridView.setAdapter(new ImageAdapter(this, filename2, filename2));
gridView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v,
int position, long id) {
int isf = filename2[position].lastIndexOf("/");
int laf = filename2[position].lastIndexOf(".");
String filename = filename2[position].substring(isf + 1, laf);
int pos = Integer.parseInt(filename);
Intent go = new Intent(Imagegallery.this, ItemsPage.class);
Bundle bundle = new Bundle();
bundle.putInt("position", pos);
bundle.putString("whichclass", "imagegallery");
bundle.putInt("catid", 2);
go.putExtras(bundle);
startActivity(go);
}
});
}
public class ImageAdapter extends BaseAdapter {
private Context context;
private final String[] mobileValues;
private final String[] mobileimages;
public ImageAdapter(Context context, String[] mobileValues, String[] mo) {
this.context = context;
this.mobileValues = mobileValues;
this.mobileimages = mo;
}
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View gridView;
if (convertView == null) {
gridView = new View(context);
gridView = inflater.inflate(R.layout.currentspeciallist, null);
TextView textView = (TextView) gridView
.findViewById(R.id.textView1);
textView.setText(mobileValues[position]);
textView.setVisibility(View.INVISIBLE);
ImageView imageView = (ImageView) gridView
.findViewById(R.id.imageView1);
imageView.setTag(mobileimages[position]);
new Loadimage().execute(imageView);
// imageView.setImageBitmap(BitmapFactory
// .decodeFile(mobileimages[position]));
} else {
gridView = (View) convertView;
}
return gridView;
}
public int getCount() {
return mobileimages.length;
}
public Object getItem(int position) {
return null;
}
public long getItemId(int position) {
return 0;
}
}
class Loadimage extends AsyncTask<Object, Void, Bitmap> {
private ImageView imv;
private String path;
@Override
protected Bitmap doInBackground(Object... params) {
imv = (ImageView) params[0];
path = imv.getTag().toString();
// Bitmap thumb = BitmapFactory.decodeFile(path);
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inSampleSize = 2; // for 1/2 the image to be loaded
Bitmap thumb = Bitmap.createScaledBitmap(
BitmapFactory.decodeFile(path, opts), 120, 120, false);
return thumb;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
if (!imv.getTag().toString().equals(path)) {
/*
* The path is not same. This means that this image view is
* handled by some other async task. We don't do anything and
* return.
*/
return;
}
if (bitmap != null && imv != null) {
imv.setVisibility(View.VISIBLE);
imv.setImageBitmap(bitmap);
} else {
imv.setVisibility(View.GONE);
}
}
}
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
}
然后创建一个xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/RelativeLayout1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="5dp" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:src="@drawable/ic_launcher" >
</ImageView>
</RelativeLayout>
我直接获取文件路径。你只需从sqlite获取名称并传递数组字符串
答案 1 :(得分：0)
使用Android-Universal-Image-Loader 并设置
ImageView imageview = (ImageView)v.findViewById(R.id.imageView1);
File imgFile = new File(imagepath);
if(imgFile.exists()){
imageLoader.displayImage(imageUri(ur file path), imageView);
}