under a Servlet Context, send a request to another AP server , get the Binary response and add some text in the response header then send the response stream back to the original client ,

FileTransportServlet.java

@Override
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws IOException {
    
        OutputStream os = null;
    
    try {
      
        URL url  = new URL(urlStr);
				URLConnection urlConnection = url.opervlet.nConnection();
				urlConnection.setRequestProperty("Connection", "close");

				System.out
						.println("after url.openConnection()     已向AP_XXX 發出 產生PDF的請求");
				InputStream inputStream = urlConnection.getInputStream();

				// 因為這邊只是中間站 所以response header要再set一次 真正的client端
				// 才取得到response header
				response.setContentType("application/pdf");
				response.setHeader("page_no1",
						urlConnection.getHeaderField("page_no1"));
				response.setHeader("page_no2",
						urlConnection.getHeaderField("page_no2"));

				// 注意要先set完 response header之後 ,才再從response裡取出OutputStream物件
				os = response.getOutputStream();

				int length;
				byte[] byteArray = new byte[4096];
				while ((length = inputStream.read(byteArray)) != -1) {
					os.write(byteArray, 0, length);
				}
				os.flush();

				System.out.println("after    os.flush()");

			} catch (IOException ioe) {

				System.out.println("向AP_XXX  發出產製pdf請求時發生錯誤 :"
						+ ioe.getMessage());

			} finally {

				if (os != null) {

					os.close();

					System.out.println("afterDoCrossOfficeThenShouldRetrievePdf   outputStream順利關閉");
				}
			}
			return;
		}

	} // doPost }