import Java.io.BufferedInputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class UrlServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//get the 'file' parameter
String fileName = (String) request.getParameter("file");
if (fileName == null fileName.equals(""))
throw new ServletException(
"Invalid or non-existent file parameter in UrlServlet servlet.");
if (fileName.indexOf(".pdf") == -1)
fileName = fileName + ".pdf";
URL pdfDir = null;
URLConnection urlConn = null;
ServletOutputStream stream = null;
BufferedInputStream buf = null;
try {
pdfDir = new URL(getServletContext().getInitParameter(
"remote-pdf-dir")
+ fileName);
} catch (MalformedURLException mue) {
throw new ServletException(mue.getMessage());
}
try {
stream = response.getOutputStream();
//set response headers
response.setContentType("application/pdf");
response.addHeader("Content-Disposition", "attachment; filename="
+ fileName);
urlConn = pdfDir.openConnection();
response.setContentLength((int) urlConn.getContentLength());
buf = new BufferedInputStream(urlConn.getInputStream());
int readBytes = 0;
//read from the file; write to the ServletOutputStream
while ((readBytes = buf.read()) != -1)
stream.write(readBytes);
} catch (IOException ioe) {
throw new ServletException(ioe.getMessage());
} finally {
if (stream != null)
stream.close();
if (buf != null)
buf.close();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
（出处：http://www.knowsky.com）
