一直使用的图片压缩的代码，做个笔记

public void commit() {
// TODO: 2016/5/23 0023 压缩图片
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(pics.get(i), options);
int height = options.outHeight;
int width = options.outWidth;
int reqHeight = 0;
int reqWidth = 480;
reqHeight = (reqWidth * height) / width;
// 在内存中创建bitmap对象，这个对象按照缩放大小创建的
options.inSampleSize = calculateInSampleSize(
options, 480, reqHeight);
options.inJustDecodeBounds = false;
Bitmap bm = BitmapFactory.decodeFile(
pics.get(i), options);
bm = compressImage(Bitmap.createScaledBitmap(
bm, 480, reqHeight, false));
bitmaps.add(bm);
}
// 压缩
private Bitmap compressImage(Bitmap image) {

ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
image.compress(Bitmap.CompressFormat.JPEG, 80, baos);
int options = 100;
// 循环判断如果压缩后图片是否大于100kb,大于继续压缩
while (baos.toByteArray().length / 1024 > 100) {
options -= 10;// 每次都减少10
baos.reset();// 重置baos即清空baos
// 这里压缩options%，把压缩后的数据存放到baos中
image.compress(Bitmap.CompressFormat.JPEG, options, baos);
}
// 把压缩后的数据baos存放到ByteArrayInputStream中
ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());
// 把ByteArrayInputStream数据生成图片
Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);
return bitmap;
}
// 计算缩放大小
private int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;

if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float) height / (float) reqHeight);
} else {
inSampleSize = Math.round((float) width / (float) reqWidth);
}
}
return inSampleSize;
}