Bitmap bmp = intent.getExtras().get("data");
int size = bmp.getRowBytes() * bmp.getHeight();
ByteBuffer b = ByteBuffer.allocate(size);
bmp.copyPixelsToBuffer(b);
byte[] bytes = new byte[size];
try {
b.get(bytes, 0, bytes.length);
} catch (BufferUnderflowException e) {
// always happens
}
// do something with byte[]
当我在调用copyPixelsToBuffer后查看缓冲区时，字节都是0…从相机返回的位图是不可变的…但这不重要，因为它正在复制。
这段代码可能有什么问题?
当前回答
试试这样做:
Bitmap bmp = intent.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
bmp.recycle();
其他回答
尝试转换字符串-位图或位图-字符串
/**
* @param bitmap
* @return converting bitmap and return a string
*/
public static String BitMapToString(Bitmap bitmap){
ByteArrayOutputStream baos=new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG,100, baos);
byte [] b=baos.toByteArray();
String temp=Base64.encodeToString(b, Base64.DEFAULT);
return temp;
}
/**
* @param encodedString
* @return bitmap (from given string)
*/
public static Bitmap StringToBitMap(String encodedString){
try{
byte [] encodeByte=Base64.decode(encodedString,Base64.DEFAULT);
Bitmap bitmap= BitmapFactory.decodeByteArray(encodeByte, 0, encodeByte.length);
return bitmap;
}catch(Exception e){
e.getMessage();
return null;
}
}
试试这样做:
Bitmap bmp = intent.getExtras().get("data");
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
bmp.recycle();
您的字节数组太小。每个像素占用4个字节，而不是1个字节，所以将你的大小乘以4，这样数组就足够大了。
这是用Kotlin写的位图扩展。converttobytearray。
/**
* Convert bitmap to byte array using ByteBuffer.
*/
fun Bitmap.convertToByteArray(): ByteArray {
//minimum number of bytes that can be used to store this bitmap's pixels
val size = this.byteCount
//allocate new instances which will hold bitmap
val buffer = ByteBuffer.allocate(size)
val bytes = ByteArray(size)
//copy the bitmap's pixels into the specified buffer
this.copyPixelsToBuffer(buffer)
//rewinds buffer (buffer position is set to zero and the mark is discarded)
buffer.rewind()
//transfer bytes from buffer into the given destination array
buffer.get(bytes)
//return bitmap's pixels
return bytes
}
Ted Hopp是正确的，摘自API文档:
public void copyPixelsToBuffer (Buffer dst)
“…该方法返回后，缓冲区的当前位置将被更新:位置将按写入缓冲区的元素数量递增。 ＂
and
public ByteBuffer get (byte[] dst, int dstOffset, int byteCount)
从指定的偏移量开始，将字节从当前位置读入指定的字节数组，并将位置增加所读的字节数。
