Question

尝试将Hasmap String，Bitmap写入文件，然后将其恢复为Hasmap;

Error : java.io.NotSerializableException: android.graphics.Bitmap

Bitmap不是一个Serializable类，所以我怎么能把它放到一个文件中并把它拿回去？

        //output file 
      fos = new FileOutputStream(Environment.getExternalStorageDirectory() + File.separator +"blts/"+"list.ser");
      ObjectOutputStream oos = new ObjectOutputStream(fos);
      oos.writeObject(hashmap);
      oos.close();

        //gethashmap
      FileInputStream fis = new FileInputStream(Environment.getExternalStorageDirectory() + File.separator +"blts/"+ "list.ser");
      ObjectInputStream ois = new ObjectInputStream(fis);
      HashList = (HashMap<String, Bitmap>)ois.readObject();
      ois.close();

Answer 1

用于序列化

ByteArrayOutputStream stream = new ByteArrayOutputStream();
currentImage.compress(Bitmap.CompressFormat.PNG, 100, stream);
BitmapDataObject bitmapDataObject = new BitmapDataObject();
bitmapDataObject.serializedBitmap = stream.toByteArray();
bitmapDataObject.serializedBitmap  = "";//your string value
out.writeObject(bitmapDataObject);

用于反序列化

BitmapDataObject bitmapDataObject = (BitmapDataObject) in.readObject();
Bitmap image = BitmapFactory.decodeByteArray(
            bitmapDataObject.imageByteArray, 0,
            bitmapDataObject.imageByteArray.length);
Sting value = bitmapDataObject.getValue();

现在您应该创建自定义类而不是使用HashMap

public class BitmapDataObject implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = 1L;
String value;
byte[] serializedBitmap;

public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}

public byte[] getSerializedBitmap() {
    return serializedBitmap;
}

public void setSerializedBitmap(byte[] serializedBitmap) {
    this.serializedBitmap = serializedBitmap;
}

}

Answer 2

由于HashMap已经是Serializable，因此无需替换它。只做一个实现Serializable位图的私有类会更方便。

private static class SerializableBitmap implements Serializable {
    private static final long serialVersionUID = 0L;

    private byte[] _compressedBitmap;

    // constructor compresses bitmap into Serializable form
    public SerializableBitmap(Bitmap bitmap) {
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
        _compressedBitmap = stream.toByteArray();
    }

    // reconstructs Bitmap for actual use
    public Bitmap getBitmap() {
        Bitmap bitmap = BitmapFactory.decodeByteArray(_compressedBitmap, 0,
                _compressedBitmap.length);

        return bitmap;
    }
}

然后您可以使用HashMap<String,SerializableBitmap>代替HashMap<String,Bitmap>。

如何将Hashmap <string，bitmap>写入文件Android </string，bitmap>

2 个答案: