package com.ruoyi.manage.util;
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import com.aspose.words.Document;
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import com.aspose.words.DocumentBuilder;
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import com.aspose.words.License;
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import com.aspose.words.SaveFormat;
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import com.ruoyi.framework.exception.ErrorException;
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import jakarta.servlet.http.HttpServletResponse;
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import org.springframework.core.io.ClassPathResource;
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import java.io.ByteArrayOutputStream;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.InputStream;
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import java.io.OutputStream;
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/**
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* 体系文件附件预览工具：把附件统一以 PDF 流输出给前端预览/盖章。
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* PDF 原样输出；Word、图片用 Aspose.Words 在线转 PDF；Excel/PPT 等无法转 PDF 的格式给出明确提示。
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*/
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public final class DocumentPreviewUtils {
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private static final String[] WORD_EXT = {".doc", ".docx", ".rtf", ".txt", ".wps"};
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private static final String[] IMAGE_EXT = {".png", ".jpg", ".jpeg", ".bmp", ".gif"};
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private DocumentPreviewUtils() {
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}
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public static void writeAsPdf(File file, HttpServletResponse response) throws Exception {
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if (file == null || !file.exists()) {
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throw new ErrorException("附件不存在或已被删除");
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}
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String name = file.getName().toLowerCase();
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if (name.endsWith(".pdf")) {
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prepare(response, file.getName(), file.length());
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try (InputStream in = new FileInputStream(file);
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OutputStream os = response.getOutputStream()) {
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in.transferTo(os);
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os.flush();
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}
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return;
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}
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Document doc;
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if (endsWithAny(name, WORD_EXT)) {
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applyLicense();
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doc = new Document(file.getPath());
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} else if (endsWithAny(name, IMAGE_EXT)) {
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applyLicense();
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doc = new Document();
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new DocumentBuilder(doc).insertImage(file.getPath());
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} else {
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throw new ErrorException("该文件格式不支持在线盖章预览，请上传 PDF 或 Word 文件");
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}
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// 先转换到内存，转换失败时响应头还没提交，前端才能收到错误信息
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ByteArrayOutputStream buffer = new ByteArrayOutputStream();
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doc.save(buffer, SaveFormat.PDF);
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byte[] bytes = buffer.toByteArray();
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prepare(response, file.getName() + ".pdf", bytes.length);
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try (OutputStream os = response.getOutputStream()) {
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os.write(bytes);
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os.flush();
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}
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}
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private static void prepare(HttpServletResponse response, String fileName, long length) {
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response.setContentType("application/pdf");
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response.setCharacterEncoding("UTF-8");
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response.setHeader("Content-disposition", "inline;filename=" + fileName);
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response.setContentLength((int) length);
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}
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private static boolean endsWithAny(String name, String[] suffixes) {
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for (String suffix : suffixes) {
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if (name.endsWith(suffix)) {
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return true;
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}
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}
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return false;
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}
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private static void applyLicense() throws Exception {
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// 凭证，否则转换后带水印
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try (InputStream is = new ClassPathResource("lib/license.xml").getInputStream()) {
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License license = new License();
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license.setLicense(is);
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}
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}
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}
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