1. ListView generation view optimization
2. LruCashe cache
3. Soft reference, weak reference (SoftReference or WeakReference), but this is not recommended. As of Android 2.3 (API level 9) the garbage collector collects soft/weak references more aggressively, which makes them rather ineffective. Also, prior to Android 3.0 (API level 11), visible bitmaps stored in native memory were not freed, potentially causing the app to temporarily exceed its memory limit and crash.
4, picture compression
This article first introduces two kinds of picture compression methods, and hope that experts will criticize and give advice.
First: Quality Compression:
private Bitmap compressImage(Bitmap image) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, 100, baos);//Quality compression method, where 100 means no compression, store the compressed data in baos
int options = 100;
while ( baos.toByteArray().length / 1024>100) { //Loop to determine if the compressed image is larger than 100kb, and continue to compress
baos.reset();//Reset baos to clear baos
options -= 10;//Reduce by 10 each time
image.compress(Bitmap.CompressFormat.JPEG, options, baos);//compress options% here, and store the compressed data in baos
}
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//Store the compressed data baos in ByteArrayInputStream
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//Generate ByteArrayInputStream data into pictures
return bitmap;
}
Second, proportional compression:
private Bitmap getimage(String srcPath) {
BitmapFactory.Options newOpts = new BitmapFactory.Options();
//Start reading the picture, set options.inJustDecodeBounds back to true at this time
newOpts.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(srcPath,newOpts);//The return bm is empty at this time
newOpts.inJustDecodeBounds = false;
int w = newOpts.outWidth;
int h = newOpts.outHeight;
//Now mainstream mobile phones are mostly 800*480 resolution, so we set the height and width to
float hh = 800f;//Here the height is set to 800f
float ww = 480f;//The width is set to 480f here
// Zoom ratio. Since it is a fixed scale scaling, only one data of height or width can be used for calculation.
int be = 1;//be=1 means no scaling
if (w > h && w > ww) {//If the width is large, it will be scaled according to the fixed size of the width
be = (int) (newOpts.outWidth / ww);
} else if (w < h && h > hh) {//If the height is high, it will be scaled according to the fixed size of the width
be = (int) (newOpts.outHeight / hh);
}
if (be <= 0)
be = 1;
newOpts.inSampleSize = be;//Set the zoom ratio
//Re-read the picture, note that options.inJustDecodeBounds has been set back to false at this time
bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
return compressImage(bitmap);//Compress the scale and then perform quality compression
}