我正在尋找一個 Java PDF 合并解決方案，我可以在從 REST API 獲?。▉碜?REST API 的示例）PDF 頁面部分的同時流式傳輸合并的 pdf。偽代碼應(yīng)該是這樣的：public void doGet(HttpServletRequest req, HttpServletResponse res) throws Exception { sOut = res.getOutputStream(); MergeDocument merger = MergeDocument.merge(sOut); for (int i = 0; i < 1000; i++) { byte[] contentPDF = restClient.get("http://mywebsite.com/files/mypdf"+i+".pdf"); merger.append(contentPDF); sOut.flush(); // sending merged PDF bytes now } sOut.close();}我的觀點是在開始將它發(fā)送給用戶之前，不要浪費內(nèi)存中所有 PDF 的堆內(nèi)存。換句話說，當(dāng)我從 rest 獲得“contentBytes pdf”時，我現(xiàn)在想將它作為流媒體發(fā)送給用戶。希望可以有人幫幫我 ：）
1 回答
收到一只叮咚
TA貢獻1821條經(jīng)驗 獲得超5個贊
使用 itextpdf
package com.example.demo.controller;
import com.itextpdf.text.Document;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.pdf.PdfCopy;
import com.itextpdf.text.pdf.PdfReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/pdf")
public class PdfMerger {
@GetMapping
public void merge(HttpServletResponse response) {
Document document = new Document(PageSize.LETTER);
response.setContentType("application/pdf");
response.setHeader("Content-disposition", "attachment; filename=\"merged.pdf\"");
OutputStream outputStream = null;
try {
outputStream = response.getOutputStream();
PdfCopy copy = new PdfCopy(document, outputStream);
document.open();
for (InputStream file : getPdfs()) {
copy.addDocument(new PdfReader(file)); // writes directly to the output stream
}
outputStream.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (document.isOpen()) {
document.close();
}
try {
if (outputStream != null) {
outputStream.close();
}
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
private List<InputStream> getPdfs() {
List<InputStream> list = new ArrayList<>();
for (int i = 0; i < 10; i++){
list.add(PdfMerger.class.getResourceAsStream("/pdf/1.pdf"));
list.add(PdfMerger.class.getResourceAsStream("/pdf/2.pdf"));
}
return list;
}
}
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