多页tif转换成一张图片

要将多页 TIFF 转换成一张图片，你可以使用 Java Advanced Imaging API（JAI）和 Java Image IO API。以下是一个示例代码：

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.plugins.tiff.TIFFImageReadParam;
import javax.imageio.plugins.tiff.TIFFImageWriteParam;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;
import javax.media.jai.JAI;
import javax.media.jai.RenderedOp;

public class TIFFUtils {

    public static BufferedImage convertToSinglePageTIFF(byte[] tiffBytes) throws IOException {
        ImageReader reader = ImageIO.getImageReadersByFormatName("TIFF").next();
        ImageInputStream iis = ImageIO.createImageInputStream(new ByteArrayInputStream(tiffBytes));
        reader.setInput(iis);

        // Read the first page
        RenderedOp op = JAI.create("stream", reader);
        BufferedImage image = op.getAsBufferedImage();

        // Write the first page to a new TIFF file
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        ImageWriter writer = ImageIO.getImageWritersByFormatName("TIFF").next();
        ImageOutputStream ios = ImageIO.createImageOutputStream(outputStream);
        writer.setOutput(ios);

        TIFFImageWriteParam writeParam = (TIFFImageWriteParam) writer.getDefaultWriteParam();
        writeParam.setCompressionMode(TIFFImageWriteParam.MODE_DEFAULT);
        writeParam.setCompressionType("LZW");

        IIOMetadata metadata = writer.getDefaultImageMetadata(reader.getImageTypes(0).next(), writeParam);
        writer.write(metadata, new javax.imageio.IIOImage(image, null, metadata), writeParam);

        // Write the rest of the pages to the new TIFF file
        for (int i = 1; i < reader.getNumImages(true); i++) {
            op = JAI.create("stream", reader);
            image = op.getAsBufferedImage();

            writer.write(null, new javax.imageio.IIOImage(image, null, null), writeParam);
        }

        writer.dispose();
        ios.close();
        iis.close();

        // Read the new TIFF file and return the image
        byte[] singlePageTiffBytes = outputStream.toByteArray();
        reader = ImageIO.getImageReadersByFormatName("TIFF").next();
        iis = ImageIO.createImageInputStream(new ByteArrayInputStream(singlePageTiffBytes));
        reader.setInput(iis);

        op = JAI.create("stream", reader);
        BufferedImage singlePageImage = op.getAsBufferedImage();

        reader.dispose();
        iis.close();
        return singlePageImage;
    }
}

这个方法接受一个多页 TIFF 的字节数组作为输入，并返回一个合并后的 BufferedImage。它首先使用 Java Image IO API 读取多页 TIFF，然后将每个页面写入一个新的单页 TIFF 文件。接下来，它使用 Java Image IO API 读取新的单页 TIFF 文件，并返回合并后的 BufferedImage。

希望这可以帮到你！