java實現文件預覽(Office轉PDF)

一、首先下載安裝openOffice軟件，下載地址：http://www.openoffice.org/download/index.html

當然，下載速度特別慢，下面是百度網盤地址。

鏈接：https://pan.baidu.com/s/1FfQa14WYXuJU2CTQf34gew 
提取碼：4q08

下載完一步一步下一步安裝好，就行了。沒什麼特別的。

二、引入jar包

  <dependency>
      <groupId>org.jodconverter</groupId>
      <artifactId>jodconverter-core</artifactId>
      <version>4.0.0-RELEASE</version>
  </dependency>

三、上代碼，註釋都很詳細，應該能看懂，主要原理呢就是講office文件轉換爲PDF，頁面可以直接打開PDF,相當於預覽

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.OutputStream;


import java.net.URL;

import org.apache.commons.io.FileUtils;
import org.jodconverter.OfficeDocumentConverter;
import org.jodconverter.office.DefaultOfficeManagerBuilder;
import org.jodconverter.office.OfficeManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;

@RestController
@RequestMapping("/filePreview")
public class FilePreview {

    private static final Logger logger = LoggerFactory.getLogger(FilePreview.class);


    //這個是爲了將uri轉爲File對象的一個臨時路徑
    private String tempPath = System.getProperty("java.io.tmpdir");

    /**
     * 預覽文件
     *
     * @param response 響應對象
     * @throws Exception
     */
    @RequestMapping("/readFile")
    public void readFile(HttpServletResponse response) throws Exception {
        try {

            File file = null;
            //文件路徑
            String uri = "http://xxx.xxx.xxx.xxx/group1/M00/00/02/wKgAuV5NSPyAK7-ZAAA8pSZux3M89.docx";
            String fileName = uri.substring(uri.lastIndexOf("/") + 1);
            //通過FileUtils將服務器文件下載的本地臨時文件夾
            URL url = new URL(uri);
            FileUtils.copyURLToFile(url, new File(tempPath + File.separator + fileName));
            //創建文件對象
            file = new File(tempPath + File.separator + fileName);
            InputStream inputStream = null;
            OutputStream outputStream = null;
            //截取文件後綴，判斷是pdf還是word還是excel,若是pdf直接讀否則轉pdf再讀
            String fileSuffix = fileName.substring(fileName.lastIndexOf("."));
            if (!fileSuffix.equals("pdf")) {
                file = openOfficeToPDF(fileName, file);
            }
            //創建文件輸入流
            if (file != null) {
                inputStream = new FileInputStream(file);
            }
            response.setContentType("application/pdf");
            outputStream = response.getOutputStream();
            byte[] b = new byte[1024];
            int length = 0;
            while ((length = inputStream.read(b)) != -1) {
                outputStream.write(b);
            }
            inputStream.close();
            outputStream.close();

        } catch (Exception e) {
            e.printStackTrace();
            logger.error(e.getMessage(), e);
        }

    }

    /**
     * 將office文檔轉換爲pdf文檔
     *
     * @return
     */
    public static File openOfficeToPDF(String fileName, File file) {
        try {
            //截取源文件文件名
            String sourceFileName = fileName.substring(0, fileName.lastIndexOf("."));
            //啓動openOffice
            DefaultOfficeManagerBuilder builder = new DefaultOfficeManagerBuilder();
            //文件轉換爲pdf後會在電腦臨時存儲，重新預覽時，清空之前之前的文件夾
            File tempfile = new File("C:/pdfFile/");
            //這個方法是我用的工具類，大家可以自己寫下，jar包我就沒有放了
            FileUtil.del(tempfile);
            //然後重新將創建file文件對象，用來存儲轉換完成的PDF文件
            String after_convert_file_path = "C:/pdfFile/" + sourceFileName + ".pdf";
            File outputFile = new File(after_convert_file_path);
            if (!outputFile.getParentFile().exists()) {
                //如果上級目錄不存在則創建一個
                outputFile.getParentFile().mkdirs();
            }
            //指定openOffice4安裝路徑，並開啓
            String openOffice4path = "C:/Program Files (x86)/OpenOffice 4";
            builder.setOfficeHome(openOffice4path);
            OfficeManager officeManager = builder.build();
            officeManager.start();
            OfficeDocumentConverter converter = new OfficeDocumentConverter(officeManager);
            //文件轉換PDF
            converter.convert(file, outputFile);
            officeManager.stop();
            return outputFile;
        } catch (Exception e) {
            e.printStackTrace();
            logger.error(e.getMessage(), e);
        }
        return null;
    }


}

注意：因爲我用的FastDfs文件服務器，所以我的文件路徑是http格式的uri,如果是本地文件就更簡單了，看下面

            File file = null;
            //文件路徑
            String uri = "http://xxx.xxx.xxx.xxx/group1/M00/00/02/wKgAuV5NSPyAK7-ZAAA8pSZux3M89.docx";
            String fileName = uri.substring(uri.lastIndexOf("/") + 1);
            //通過FileUtils將服務器文件下載的本地臨時文件夾
            URL url = new URL(uri);
            FileUtils.copyURLToFile(url, new File(tempPath + File.separator + fileName));
            //創建文件對象
            file = new File(tempPath + File.separator + fileName);

            上面這段直接改成
            File file = new File("文件路徑") 就好了