用Java编写图像元数据，最好是PNG

几天前，我不得不做同样的事情。.我也没有在互联网上找到确切的解决方案，但看着这

com.sun.imageio.plugins.png.PNGmetadata

要将自定义元数据写入PNG文件：

public byte[] writeCustomData(BufferedImage buffImg, String key, String value) throws Exception {    ImageWriter writer = ImageIO.getImageWritersByFormatName("png").next();    ImageWriteParam writeParam = writer.getDefaultWriteParam();    ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);    //adding metadata    IIOmetadata metadata = writer.getDefaultImagemetadata(typeSpecifier, writeParam);    IIOmetadataNode textEntry = new IIOmetadataNode("tEXtEntry");    textEntry.setAttribute("keyword", key);    textEntry.setAttribute("value", value);    IIOmetadataNode text = new IIOmetadataNode("tEXt");    text.appendChild(textEntry);    IIOmetadataNode root = new IIOmetadataNode("javax_imageio_png_1.0");    root.appendChild(text);    metadata.mergeTree("javax_imageio_png_1.0", root);    //writing the data    ByteArrayOutputStream baos = new ByteArrayOutputStream();    ImageOutputStream stream = ImageIO.createImageOutputStream(baos);    writer.setOutput(stream);    writer.write(metadata, new IIOImage(buffImg, null, metadata), writeParam);    stream.close();    return baos.toByteArray();}

然后，读取数据：

public String readCustomData(byte[] imageData, String key) throws IOException{    ImageReader imageReader = ImageIO.getImageReadersByFormatName("png").next();    imageReader.setInput(ImageIO.createImageInputStream(new ByteArrayInputStream(imageData)), true);    // read metadata of first image    IIOmetadata metadata = imageReader.getImagemetadata(0);    //this cast helps getting the contents    PNGmetadata pngmeta = (PNGmetadata) metadata;     NodeList childNodes = pngmeta.getStandardTextNode().getChildNodes();    for (int i = 0; i < childNodes.getLength(); i++) {        Node node = childNodes.item(i);        String keyword = node.getAttributes().getNamedItem("keyword").getNodevalue();        String value = node.getAttributes().getNamedItem("value").getNodevalue();        if(key.equals(keyword)){ return value;        }    }    return null;}