java 如何序列化包含 BufferedImages 的对象
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How to serialize an object that includes BufferedImages
提问by scaevity
I'm trying to create a simple image editing program in java. I made an ImageCanvasobject that has all the information about the image that is being edited (some basic properties, list of effects being applied, a list of BufferedImagelayers, etc.) and I wanted a simple way to save it to disk so it could be opened again later.
我正在尝试用 Java 创建一个简单的图像编辑程序。我制作了一个ImageCanvas对象，其中包含正在编辑的图像的所有信息（一些基本属性、应用的效果列表、BufferedImage图层列表等），我想要一种简单的方法将其保存到磁盘，以便它可以后来又开了。
I figured that using Java's defualt Serializableinterface might be exactly what I was looking for and I could just write the entire object to file and read it back into memory again at a later time. However, ImageCanvasincludes an ArrayList<BufferedImage>, and BufferedImage's are not serializable (everything else is).
我认为使用 Java 的默认Serializable接口可能正是我正在寻找的，我可以将整个对象写入文件并在稍后再次将其读回内存。但是，ImageCanvas包括ArrayList<BufferedImage>, 和BufferedImage是不可序列化的（其他都是）。
I know it is possible to override the writeObject()and readObject()methods, but I have never done so and I was wondering if there is any easy way to have Java serialize everything else and have some custom way to read/write the BufferedImage's to disk? Or is there some other way to easily write the entire ImageCanvasobject to disk that I'm overlooking? Eventually I might implement my own custom image file type, but for right now I wanted a quick and easy way to save files temporarily while I am testing (the ImageCanvasclass will change a lot, so I didn't want to have to keep updating my custom file type before I have it finalized).
我知道可以覆盖writeObject()和readObject()方法，但我从来没有这样做过，我想知道是否有任何简单的方法可以让 Java 序列化其他所有内容，并有一些自定义的方式来读/写BufferedImage's 到磁盘？或者是否有其他方法可以轻松地将整个ImageCanvas对象写入我忽略的磁盘？最终我可能会实现我自己的自定义图像文件类型，但现在我想要一种快速简便的方法来在我测试时临时保存文件（ImageCanvas类会发生很大变化，所以我不想一直更新我的在我最终确定之前自定义文件类型）。
回答by Sam Barnum
make your ArrayList<BufferedImage>transient, and implement a custom writeObject()method. In this, write the regular data for your ImageCanvas, then manually write out the byte data for the images, using PNG format.
使您的ArrayList<BufferedImage>瞬态，并实现自定义writeObject()方法。在此，为 ImageCanvas 写入常规数据，然后使用 PNG 格式手动写出图像的字节数据。
class ImageCanvas implements Serializable {
transient List<BufferedImage> images;
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
out.writeInt(images.size()); // how many images are serialized?
for (BufferedImage eachImage : images) {
ImageIO.write(eachImage, "png", out); // png is lossless
}
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
final int imageCount = in.readInt();
images = new ArrayList<BufferedImage>(imageCount);
for (int i=0; i<imageCount; i++) {
images.add(ImageIO.read(in));
}
}
}
回答by Darrell Teague
Serialization is pretty straight-forward in that it persists static data. You are otherwise in the right place with read/write object in the Serialization family of methods. Think about what a "BufferedImage" is. It is a buffered streaming implementation. To serialize, the data must be flushed out to a static object like a byte[] array and then THAT object may be serialized/deserialized into/out of a BufferedImage such that the buffered streaming now comes in/out of that byte[] array.
序列化非常简单，因为它保留静态数据。否则，您在序列化方法系列中使用读/写对象是正确的。想想“BufferedImage”是什么。它是一个缓冲流实现。要序列化，必须将数据刷新到像 byte[] 数组这样的静态对象，然后该对象可以序列化/反序列化到 BufferedImage 中/从 BufferedImage 中取出，这样缓冲的流现在就可以进入/退出该 byte[] 数组.
