使用com.sun.imageio.plugins.png.PNGMetadata讀取圖片的元數據
阿新 • • 發佈:2018-10-20
close complete ets meta getc puts 打印 fileinput pack
所謂圖片元數據,就是除了我們肉眼看到的圖片內容外,隱藏在這些內容背後的一些技術數據。
本文介紹如何使用Java代碼將一張圖片的隱藏信息讀取出來。
首先不需要下載任何額外的Java庫,用JDK自帶的庫就能工作。
import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import javax.imageio.ImageIO; import javax.imageio.ImageReader; import javax.imageio.metadata.IIOMetadata; import javax.imageio.metadata.IIOMetadataNode; import org.w3c.dom.NamedNodeMap; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import com.sun.imageio.plugins.png.PNGMetadata; 新建一個Java類,這個類的main方法也是非常直接的: static public void main(String[] arg) throws IOException{ byte[] content = getContent("C:\Users\i042416\Desktop\test\clipboard1.png"); readCustomData(content); }
首先把桌面上名叫clipboard1.png的圖片文件的內容讀到字節數組content中。
getContent方法的代碼:
一張png圖片的元數據,散布在下面這些節點裏:
printNode(pngmeta.getStandardChromaNode()); printNode(pngmeta.getStandardCompressionNode()); printNode(pngmeta.getStandardDataNode()); printNode(pngmeta.getStandardDimensionNode()); printNode(pngmeta.getStandardDocumentNode()); printNode(pngmeta.getStandardTextNode()); printNode(pngmeta.getStandardTransparencyNode());
通過printNode打印出來:
printNode方法的源代碼:
打印出來的元數據:
如果大家想要復制粘貼,這是全部的源代碼:
package image; import java.io.ByteArrayInputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import javax.imageio.ImageIO; import javax.imageio.ImageReader; import javax.imageio.metadata.IIOMetadata; import javax.imageio.metadata.IIOMetadataNode; import org.w3c.dom.NamedNodeMap; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import com.sun.imageio.plugins.png.PNGMetadata; public class pngTest { static private byte[] getContent(String filePath) throws IOException { File file = new File(filePath); long fileSize = file.length(); if (fileSize > Integer.MAX_VALUE) { System.out.println("file too big..."); return null; } FileInputStream fi = new FileInputStream(file); byte[] buffer = new byte[(int) fileSize]; int offset = 0; int numRead = 0; while (offset < buffer.length && (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) { offset += numRead; } if (offset != buffer.length) { fi.close(); throw new IOException("Could not completely read file " + file.getName()); } fi.close(); return buffer; } static private void readCustomData(byte[] imageData) throws IOException{ ImageReader imageReader = ImageIO.getImageReadersByFormatName("png").next(); imageReader.setInput(ImageIO.createImageInputStream(new ByteArrayInputStream(imageData)), true); IIOMetadata metadata = imageReader.getImageMetadata(0); PNGMetadata pngmeta = (PNGMetadata) metadata; printNode(pngmeta.getStandardChromaNode()); printNode(pngmeta.getStandardCompressionNode()); printNode(pngmeta.getStandardDataNode()); printNode(pngmeta.getStandardDimensionNode()); printNode(pngmeta.getStandardDocumentNode()); printNode(pngmeta.getStandardTextNode()); printNode(pngmeta.getStandardTransparencyNode()); } static private void printNode(IIOMetadataNode metanode){ if (metanode == null) return; NodeList childNodes = metanode.getChildNodes(); if( childNodes == null) return; for (int i = 0; i < childNodes.getLength(); i++) { Node node = childNodes.item(i); NamedNodeMap attribute = node.getAttributes(); if( attribute == null) continue; int length = attribute.getLength(); for( int j = 0; j < length; j++){ Node each = attribute.item(j); String value = each.getNodeValue(); String name = each.getNodeName(); System.out.println("Name: " + name + " value: " + value); } } } static public void main(String[] arg) throws IOException{ byte[] content = getContent("C:\Users\i042416\Desktop\test\clipboard1.png"); readCustomData(content); } }
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使用com.sun.imageio.plugins.png.PNGMetadata讀取圖片的元數據