208_打开相册选择图片并返回

//先创建一个intent
//给一个action,再给一个uri
//action给Intent.ACTION_PICK
//uri给android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

//然后设置一个type为"image/*"
intent.setType("image/*");

//启动activity
startActivityForResult(intent, 0);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Uri uri = data.getData();
try {
Bitmap bitmap = getBitmapFormUri(this, uri);

mIv.setImageBitmap(bitmap);
} catch (IOException e) {

}
}

public Bitmap getBitmapFormUri(Activity ac, Uri uri) throws FileNotFoundException, IOException {
InputStream input = ac.getContentResolver().openInputStream(uri);
BitmapFactory.Options onlyBoundsOptions = new BitmapFactory.Options();
onlyBoundsOptions.inJustDecodeBounds = true;
onlyBoundsOptions.inDither = true;//optional
onlyBoundsOptions.inPreferredConfig = Bitmap.Config.ARGB_8888;//optional
BitmapFactory.decodeStream(input, null, onlyBoundsOptions);
input.close();
int originalWidth = onlyBoundsOptions.outWidth;
int originalHeight = onlyBoundsOptions.outHeight;
if ((originalWidth == -1) || (originalHeight == -1))
return null;
//图片分辨率以480x800为标准
float hh = 800f;//这里设置高度为800f
float ww = 480f;//这里设置宽度为480f
//缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可
int be = 1;//be=1表示不缩放
if (originalWidth > originalHeight && originalWidth > ww) {//如果宽度大的话根据宽度固定大小缩放
be = (int) (originalWidth / ww);
} else if (originalWidth < originalHeight && originalHeight > hh) {//如果高度高的话根据宽度固定大小缩放
be = (int) (originalHeight / hh);
}
if (be <= 0)
be = 1;
//比例压缩
BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
bitmapOptions.inSampleSize = be;//设置缩放比例
bitmapOptions.inDither = true;//optional
bitmapOptions.inPreferredConfig = Bitmap.Config.ARGB_8888;//optional
input = ac.getContentResolver().openInputStream(uri);
Bitmap bitmap = BitmapFactory.decodeStream(input, null, bitmapOptions);
input.close();

return bitmap;
}