如何用 Java 實現(xiàn)word、excel、ppt、txt等辦公文件在線預(yù)覽功能？本文告訴你答案！

java 實現(xiàn)辦公文件在線預(yù)覽功能是一個大家在工作中也許會遇到的需求，網(wǎng)上些公司專門提供這樣的服務(wù)，不過需要收費。

如果想要免費的，可以用 openoffice，實現(xiàn)原理就是：
通過第三方工具openoffice，將word、excel、ppt、txt等文件轉(zhuǎn)換為pdf文件流；當(dāng)然如果裝了Adobe Reader XI，那把pdf直接拖到瀏覽器頁面就可以直接打開預(yù)覽，前提就是瀏覽器支持pdf文件瀏覽。

我這里介紹通過poi實現(xiàn)word、excel、ppt轉(zhuǎn)pdf流，這樣就可以在瀏覽器上實現(xiàn)預(yù)覽了。

到官網(wǎng)下載 Apache OpenOffice：

https://www.openoffice.org/download

安裝包，安裝運行。（不同系統(tǒng)的安裝方法，自行百度，這里不做過多說明）

再項目的pom文件中引入依賴

????com.artofsolving
????jodconverter
????2.2.1

將word、excel、ppt轉(zhuǎn)換為pdf流的工具類代碼

import?com.artofsolving.jodconverter.DefaultDocumentFormatRegistry;
import?com.artofsolving.jodconverter.DocumentConverter;
import?com.artofsolving.jodconverter.DocumentFormat;
import?com.artofsolving.jodconverter.openoffice.connection.OpenOfficeConnection;
import?com.artofsolving.jodconverter.openoffice.connection.SocketOpenOfficeConnection;
import?com.artofsolving.jodconverter.openoffice.converter.StreamOpenOfficeDocumentConverter;

import?java.io.*;
import?java.net.HttpURLConnection;
import?java.net.URL;
import?java.net.URLConnection

/** ?*?文件格式轉(zhuǎn)換工具類 ?*/
public?class?FileConvertUtil?{
????/**?默認(rèn)轉(zhuǎn)換后文件后綴?*/
????private?static?final?String?DEFAULT_SUFFIX?=?"pdf";
????/**?openoffice_port?*/
????private?static?final?Integer?OPENOFFICE_PORT?=?8100;

????/** ?????*?方法描述?office文檔轉(zhuǎn)換為PDF(處理本地文件) ?????* ?????*?@param?sourcePath?源文件路徑 ?????*?@param?suffix?????源文件后綴 ?????*?@return?InputStream?轉(zhuǎn)換后文件輸入流 ?????*/
????public?static?InputStream?convertLocaleFile(String?sourcePath,?String?suffix)?throws?Exception?{
????????File?inputFile?=?new?File(sourcePath);
????????InputStream?inputStream?=?new?FileInputStream(inputFile);
????????return?covertCommonByStream(inputStream,?suffix);
????}

????/** ?????*?方法描述??office文檔轉(zhuǎn)換為PDF(處理網(wǎng)絡(luò)文件) ?????* ?????*?@param?netFileUrl?網(wǎng)絡(luò)文件路徑 ?????*?@param?suffix?????文件后綴 ?????*?@return?InputStream?轉(zhuǎn)換后文件輸入流 ?????*/
????public?static?InputStream?convertNetFile(String?netFileUrl,?String?suffix)?throws?Exception?{
????????//?創(chuàng)建URL
????????URL?url?=?new?URL(netFileUrl);
????????//?試圖連接并取得返回狀態(tài)碼
????????URLConnection?urlconn?=?url.openConnection();
????????urlconn.connect();
????????HttpURLConnection?httpconn?=?(HttpURLConnection)?urlconn;
????????int?httpResult?=?httpconn.getResponseCode();
????????if?(httpResult?==?HttpURLConnection.HTTP_OK)?{
????????????InputStream?inputStream?=?urlconn.getInputStream();
????????????return?covertCommonByStream(inputStream,?suffix);
????????}
????????return?null;
????}

/** ?????
*?方法描述??將文件以流的形式轉(zhuǎn)換 ?????
* ?????
*?@param?inputStream?源文件輸入流 ?????
*?@param?suffix??????源文件后綴 ?????
*?@return?InputStream?轉(zhuǎn)換后文件輸入流 ?????
*/
????public?static?InputStream?covertCommonByStream(InputStream?inputStream,?String?suffix)?throws?Exception?{
????????ByteArrayOutputStream?out?=?new?ByteArrayOutputStream();
????????OpenOfficeConnection?connection?=?new?SocketOpenOfficeConnection(OPENOFFICE_PORT);
????????connection.connect();
????????DocumentConverter?converter?=?new?StreamOpenOfficeDocumentConverter(connection);
????????DefaultDocumentFormatRegistry?formatReg?=?new?DefaultDocumentFormatRegistry();
????????DocumentFormat?targetFormat?=?formatReg.getFormatByFileExtension(DEFAULT_SUFFIX);
????????DocumentFormat?sourceFormat?=?formatReg.getFormatByFileExtension(suffix);
????????converter.convert(inputStream,?sourceFormat,?out,?targetFormat);
????????connection.disconnect();
????????return?outputStreamConvertInputStream(out);
????}

????/** ?????*?方法描述?outputStream轉(zhuǎn)inputStream ?????*/
????public?static?ByteArrayInputStream?outputStreamConvertInputStream(final?OutputStream?out)?throws?Exception?{
????????ByteArrayOutputStream?baos=(ByteArrayOutputStream)?out;
????????return?new?ByteArrayInputStream(baos.toByteArray());
????}

????public?static?void?main(String[]?args)?throws?IOException?{
????????//convertNetFile("http://172.16.10.21/files/home/upload/department/base/201912090541573c6abdf2394d4ae3b7049dcee456d4f7.doc",?".pdf");
????????//convert("c:/Users/admin/Desktop/2.pdf",?"c:/Users/admin/Desktop/3.pdf");
????}
}

serve層在線預(yù)覽方法代碼

/** ?
*?@Description:系統(tǒng)文件在線預(yù)覽接口 ?
*?@Author:?tarzan ?
*/
public?void?onlinePreview(String?url,?HttpServletResponse?response)?throws?Exception?{
????//獲取文件類型
????String[]?str?=?SmartStringUtil.split(url,"\\.");

????if(str.length==0){
????????throw?new?Exception("文件格式不正確");
????}
????String?suffix?=?str[str.length-1];
????if(!suffix.equals("txt")?&&?!suffix.equals("doc")?&&?!suffix.equals("docx")?&&?!suffix.equals("xls")
????????????&&?!suffix.equals("xlsx")?&&?!suffix.equals("ppt")?&&?!suffix.equals("pptx")){
????????throw?new?Exception("文件格式不支持預(yù)覽");
????}
????InputStream?in=FileConvertUtil.convertNetFile(url,suffix);
????OutputStream?outputStream?=?response.getOutputStream();
????//創(chuàng)建存放文件內(nèi)容的數(shù)組
????byte[]?buff?=new?byte[1024];
????//所讀取的內(nèi)容使用n來接收
????int?n;
????//當(dāng)沒有讀取完時,繼續(xù)讀取,循環(huán)
????while((n=in.read(buff))!=-1){
????????//將字節(jié)數(shù)組的數(shù)據(jù)全部寫入到輸出流中
????????outputStream.write(buff,0,n);
????}
????//強制將緩存區(qū)的數(shù)據(jù)進行輸出
????outputStream.flush();
????//關(guān)流
????outputStream.close();
????in.close();
}

controler層代碼

@ApiOperation(value?=?"系統(tǒng)文件在線預(yù)覽接口")
@PostMapping("/api/file/onlinePreview")
public?void?onlinePreview(@RequestParam("url")?String?url,?HttpServletResponse?response)?throws?Exception{
????fileService.onlinePreview(url,response);
}

效果展示：

在線預(yù)覽execl

預(yù)覽word