Android：从Uri压缩位图

使用普通智能手机摄像头拍照

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

好吧，我已经在谷歌上搜索了一段时间，每个人似乎都在使用下面的东西：

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

我使用此选项检查文件大小：

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

@TargetApi(Build.VERSION_CODES.HONEYCOMB_MR1)
protected int sizeOf(Bitmap data) {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB_MR1) {
        return data.getRowBytes() * data.getHeight();
    } else {
        return data.getByteCount();
    }
}

结果:

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

11-05 02:51:52.739: D/image(2558): 20155392
11-05 02:51:52.739: D/image(2558): 20155392

指针

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

回答：

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 50;
Bitmap bmpSample = BitmapFactory.decodeFile(fileUri.getPath(), options);

Log.d("image", sizeOf(bmpPic)+"");

ByteArrayOutputStream out = new ByteArrayOutputStream();                
bmSample.compress(Bitmap.CompressFormat.JPEG, 1, out);
byte[] byteArray = out.toByteArray();

Log.d("image", byteArray.length/1024+"");

---

压缩方法，如文档中所述：

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

将位图的压缩版本写入指定的输出流。通过将相应的inputstream传递给
BitmapFactory.decodeStream（）

Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));

因此，变量
out
现在包含压缩位图。由于您在调用
decodeStream
后检查了大小，位图已解压缩并返回给您。因此大小是相同的。
在调用sizeOf（位图数据）之后，您将日志语句放在何处！你能用密码寄吗？我觉得您可能正在记录相同大小的数据。。因此输出是相同的。@AmulyaKhare我也这么认为，但我仔细检查了一下，我知道输出是在同一秒（奇怪的：S）。请看我的答案。。解释输出相同的原因。。如果您试图在屏幕上显示压缩版本，则应使用
inSampleSize
。。读这个
Bitmap bm = BitmapFactory.decodeStream(getContentResolver().openInputStream(fileUri));
ByteArrayOutputStream out = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 25, out);
Bitmap decoded = BitmapFactory.decodeStream(new ByteArrayInputStream(out.toByteArray()));