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
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;
}
}
其他回答
也许你需要倒带缓冲器?
同样，如果位图的步幅(以字节为单位)大于行长(以像素*字节/像素为单位)，也可能发生这种情况。使字节的长度为b.remaining()而不是size。
使用下面的函数将位图编码为字节[]，反之亦然
public static String encodeTobase64(Bitmap image) {
Bitmap immagex = image;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
immagex.compress(Bitmap.CompressFormat.PNG, 90, baos);
byte[] b = baos.toByteArray();
String imageEncoded = Base64.encodeToString(b, Base64.DEFAULT);
return imageEncoded;
}
public static Bitmap decodeBase64(String input) {
byte[] decodedByte = Base64.decode(input, 0);
return BitmapFactory.decodeByteArray(decodedByte, 0, decodedByte.length);
}
压缩格式太慢…
ByteBuffer试试。
※※※位图到字节※※※
width = bitmap.getWidth();
height = bitmap.getHeight();
int size = bitmap.getRowBytes() * bitmap.getHeight();
ByteBuffer byteBuffer = ByteBuffer.allocate(size);
bitmap.copyPixelsToBuffer(byteBuffer);
byteArray = byteBuffer.array();
※※※真佩服to bitmap※※※
Bitmap.Config configBmp = Bitmap.Config.valueOf(bitmap.getConfig().name());
Bitmap bitmap_tmp = Bitmap.createBitmap(width, height, configBmp);
ByteBuffer buffer = ByteBuffer.wrap(byteArray);
bitmap_tmp.copyPixelsFromBuffer(buffer);
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;
}
}
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
}
