java - 使用序列化代理模式不需要 writeObject() 吗？

Question

我正在为我的一堆类使用序列化代理模式，并且最近将 FindBugs 添加到我的构建过程中，现在我想知道 FindBugs 是否正确......

这是有问题的类:

public class Block implements Serializable {
    private static final long serialVersionUID = 584958030434385L;

    private final float confidence;
    private final Rectangle boundingBox;
    private final Rectangle baseline;
    private final BufferedImage binaryImage;
    private final List<Paragraph> paragraphs;

    private TessResult parentTessResult;

    private Block(final float confidence, final Rectangle boundingBox, final Rectangle baseline, final BufferedImage binaryImage, final List<Paragraph> paragraphs) {
        this.confidence = confidence;
        this.boundingBox = Objects.requireNonNull(boundingBox, "boundingBox");
        this.baseline = Objects.requireNonNull(baseline, "baseline");
        this.binaryImage = binaryImage;
        this.paragraphs = Objects.requireNonNull(paragraphs, "paragraphs");
    }

    void setParentTessResult(final TessResult parentTessResult) {
        this.parentTessResult = Objects.requireNonNull(parentTessResult, "parentTessResult");
    }

    public float getConfidence() {
        return confidence;
    }

    public Rectangle getBoundingBox() {
        return boundingBox;
    }

    public Rectangle getBaseline() {
        return baseline;
    }

    public BufferedImage getBinaryImage() {
        return binaryImage;
    }

    public List<Paragraph> getParagraphs() {
        return paragraphs;
    }

    public TessResult getParentTessResult() {
        return parentTessResult;
    }

    public static class BlockBuilder {
        private final float confidence;
        private final Rectangle boundingBox;
        private final Rectangle baseline;
        private final BufferedImage binaryImage;
        private final List<Paragraph> paragraphs = new ArrayList<>();

        public BlockBuilder(final float confidence, final Rectangle boundingBox, final Rectangle baseline, final BufferedImage binaryImage) {
            this.confidence = confidence;
            this.boundingBox = boundingBox;
            this.baseline = baseline;
            this.binaryImage = binaryImage;
        }

        public BlockBuilder addParagraph(final Paragraph paragraph) {
            paragraphs.add(Objects.requireNonNull(paragraph, "paragraph"));
            return this;
        }

        public Block build() {
            return new Block(confidence, boundingBox, baseline, binaryImage, paragraphs);
        }
    }

    private Object writeReplace() throws IOException {
        return new SerializationProxy(this);
    }

    private void readObject(final ObjectInputStream stream) throws InvalidObjectException {
        throw new InvalidObjectException("Proxy required");
    }

    private static class SerializationProxy implements Serializable {
        private static final long serialVersionUID = 12321313232553L;

        private final float confidence;
        private final Rectangle boundingBox;
        private final Rectangle baseline;
        private final byte[] binaryImageBytes;
        private final List<Paragraph> paragraphs;

        private SerializationProxy(final Block block) throws IOException {
            this.confidence = block.confidence;
            this.boundingBox = block.boundingBox;
            this.baseline = block.baseline;
            this.binaryImageBytes = bufferedImageToBytes(block.binaryImage);
            this.paragraphs = block.paragraphs;
        }

        private Object readResolve() throws IOException {
            BufferedImage binaryImage = bytesToBufferedImage(binaryImageBytes);
            Block block = new Block(confidence, boundingBox, baseline, binaryImage, paragraphs);
            for (Paragraph paragraph : paragraphs) {
                paragraph.setParentBlock(block);
            }
            return block;
        }
    }
}

要观察的关键点是它存储了 BufferedImage，但在内部它将 BufferedImage 存储为 byte[] 以进行序列化。

现在我从 FindBugs 收到此警告:

Class com.yob.dpc2.ocr.utils.data.Block defines non-transient non-serializable instance field binaryImage ["com.yob.dpc2.ocr.utils.data.Block"] At Block.java:[lines 18-95]

因此，我深入研究了这个问题，发现我没有提供 private void writeObject(ObjectOutputStream oos) throws IOException...

所以我的问题是:我应该提供 writeObject() 方法吗？如果是这样，有没有办法可以重用 writeReplace() 方法或执行其他操作来防止逻辑重复？

Answer 1

Should I provide that writeObject() method?

不，因为你的 writeReplace() 方法永远无法调用它。

您在 FindBugs 中遇到了限制。让您的类(class)成为一个异常(exception)。