如何在Java中从Thumbs.db文件中提取图像？

Question

你好，我了解POI项目并尝试从thumbs.db中提取图像，但在代码中遇到了异常。代码如下：

InputStream stream = new FileInputStream("C:\\Thumbs.db");
POIFSFileSystem fs = new POIFSFileSystem(stream);
DirectoryEntry root = fs.getRoot();
Entry entry = root.getEntry("2");
DocumentInputStream is = fs.createDocumentInputStream(entry.getName());
JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(is);
JPEGDecodeParam param = JPEGCodec.getDefaultJPEGEncodeParam(4,    JPEGDecodeParam.COLOR_ID_RGBA);
decoder.setJPEGDecodeParam(param);
BufferedImage originalBufferedImage = decoder.decodeAsBufferedImage();

当出现“com.sun.image.codec.jpeg.ImageFormatException：Not a JPEG file：starts with 0x0c 0x00”异常时，出现了什么问题？

您能否建议其他完成此任务的方法？

- Sachin Doiphode

Answer 1

在提取图像之前，您需要读取Thumbs.db文件的标头。尝试使用我下面添加的更改，它应该可以解决您遇到的ImageFormatException问题。

InputStream stream = new FileInputStream("C:\\Thumbs.db");
POIFSFileSystem fs = new POIFSFileSystem(stream);
DirectoryEntry root = fs.getRoot();
Entry entry = root.getEntry("2");
DocumentInputStream is = fs.createDocumentInputStream(entry.getName());

//Added to read the header lines and fix the ImageFormatException
int header_len = is.read();
for (int i = 1; i < header_len; i++) {
        is.read();
}

JPEGImageDecoder decoder = JPEGCodec.createJPEGDecoder(is);
JPEGDecodeParam param = JPEGCodec.getDefaultJPEGEncodeParam(4,JPEGDecodeParam.COLOR_ID_RGBA);
decoder.setJPEGDecodeParam(param);
BufferedImage originalBufferedImage = decoder.decodeAsBufferedImage();

我希望您能从中受益！

- bamana