当我从SD卡加载图像时,我得到了例外
java.lang.OutOfMemoryError at android.graphics.BitmapFactory.nativeDecodeStream(Native Method)
这是我的代码:
public class Images extends Activity implements OnItemLongClickListener {
private Uri[] mUrls;
String[] mFiles = null;
ImageView selectImage;
Gallery g;
static final String MEDIA_PATH = new String("/mnt/sdcard/DCIM/Camera/");
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
selectImage = (ImageView) findViewById(R.id.image);
g = (Gallery) findViewById(R.id.gallery);
File images = new File(MEDIA_PATH);
Log.i("files", images.getAbsolutePath());
File[] imagelist = images.listFiles(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return ((name.endsWith(".jpg")) || (name.endsWith(".png")));
}
});
Log.i("files", imagelist.toString());
String[] mFiles = null;
mFiles = new String[imagelist.length];
for (int i = 0; i < imagelist.length; i++) {
mFiles[i] = imagelist[i].getAbsolutePath();
}
System.out.println(mFiles.length);
mUrls = new Uri[mFiles.length];
System.out.println(mUrls.length);
for (int i = 0; i < mFiles.length; i++) {
mUrls[i] = Uri.parse(mFiles[i]);
}
g.setAdapter(new ImageAdapter(this));
// g.setOnItemSelectedListener(this);
g.setOnItemLongClickListener(this);
}
public class ImageAdapter extends BaseAdapter {
// int mGalleryItemBackground;
public ImageAdapter(Context c) {
mContext = c;
}
public int getCount() {
return mUrls.length;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
Log.i("ok5", "ok");
ImageView i = new ImageView(mContext);
i.setImageURI(mUrls[position]);
Log.i("ok", "ok");
i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
i.setLayoutParams(new Gallery.LayoutParams(100, 100));
return i;
}
private Context mContext;
}
@Override
public boolean onItemLongClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
selectImage.setImageURI(mUrls[arg2]);
System.out.println("path: "+mUrls[arg2]);
Uri f = mUrls[arg2];
File f1 = new File(f.toString());
System.out.println("f1: "+f1);
return false;
}
答案 0 :(得分:0)
当您加载大型位图文件时,BitmapFactory类提供了几种解码方法(decodeByteArray(),decodeFile(),decodeResource()等。)。
第1步
在解码时将inJustDecodeBounds属性设置为true可避免内存分配,为位图对象返回null但设置outWidth,outHeight和outMimeType。此技术允许您在构造(和内存分配)位图之前读取图像数据的尺寸和类型。
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
To avoid java.lang.OutOfMemory exceptions, check the dimensions of a bitmap before decoding it.
第2步
告诉解码器对图像进行二次采样,将较小的版本加载到内存中,在BitmapFactory.Options对象中将inSampleSize设置为true。
例如,使用inSampleSize为4解码的分辨率为2048x1536的图像会产生大约512x384的位图。将其加载到内存中对于完整图像使用0.75MB而不是12MB。
这是一种根据目标宽度和高度计算样本大小值为2的幂的方法:
public static Bitmap decodeSampledBitmapFromResource(Resources res, int resId,
int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(res, resId, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(res, resId, options);
}
public static int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) > reqHeight
&& (halfWidth / inSampleSize) > reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
请阅读此链接了解详情。 http://developer.android.com/training/displaying-bitmaps/load-bitmap.html