java - 将 URL 映射到本地系统上的文件

Question

我想将 URL 重定向到我服务器上的文件，这样当打开该 URL 时，它会从服务器获取特定的 pdf 文件并在浏览器上打开它。它适用于客户端服务器接口。请帮助我如何将我的 URL 重定向到我服务器上的特定文件。

Answer 1

如果我正确理解您的问题，假设您有以下网址：

http://somesiste.bla/render?path=/dirx/hello1.pdf

如果 PDF 文件位于您的应用程序 WAR 文件中，并且您的 WAR 文件看起来像这样

WAR
 -- index.jspx
 -- WEB-INF
    --web.xml
 -- data
    --dirx
      --hello01.pdf
      --hello02.pdf

那么这真的很容易，只需转发到您的应用程序中的正确文件

public void forwardToPdf( HttpServletRequest request,    HttpServletResponse response, String path ) throws ServletException, IOException
   {
   RequestDispatcher requestDispatcher= request.getRequestDispatcher("/data/" +path) ;                 
   requestDispatcher.forward( request, response ) ;
   }

// Get the parameter and pass it on
String path = getParameter("path");
forwardToPdf(request, response, path);

但是如果文件位于您的应用程序之外，可以说

C:\data\

您不能只重定向到该文件，您要做的就是读入该文件并将其呈现给用户

只是一个小实用程序来做到这一点。

import java.io.Closeable;
import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
    public class FileDownloadHelper {

    public static final String CONTENT_TYPE_EXCEL ="application/vnd.ms-excel";
    public static final String CONTENT_TYPE_WORD_DOCUMENT ="application/doc";
    public static final String CONTENT_TYPE_MS_WORD ="application/msword";
    public static final String CONTENT_TYPE_PDF ="application/pdf";

    public static final String CONTENT_DISPOSITION_INLINE ="inline";
    public static final String CONTENT_DISPOSITION_ATTACHMENT ="attachment";

    public void write(HttpServletResponse response, byte[] data, String contentType, String outputFileName, String contentDisposition){
        response.setCharacterEncoding("UTF-8");
        ServletOutputStream sos = null;
        try {   
            sos = response.getOutputStream();
            response.setStatus(HttpServletResponse.SC_OK);

            if(data != null){

                response.setContentType(contentType);
                long contentLength = data.length;
                /* IE requires the following for pdf files */
                response.setBufferSize((int)contentLength);
                //This enables us to show estimated download time
                response.setHeader("Content-Length", String.valueOf(contentLength));
                // inline=forces to use a viewer  attachment=show save dialog            
                //response.setHeader("Content-Disposition", "inline; filename=\"" + outputFileName + "\"");
                response.setHeader("Content-Disposition", contentDisposition+"; filename=\"" + outputFileName + "\"");
                // These set of headers need to be here for this to work with IE  with servlet security
                // This will prevent catching of the results
                response.setHeader("Expires", "0");
                response.setHeader("Cache-Control", "must-revalidate, post-check=0, pre-check=0");
                response.setHeader("Pragma", "public");

                sos.write(data);
            }else{
                sendResponse404(response);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            close(sos);
        }   
    }



    /**
     * Helper method to send 404 - Resource not found message
     * @param response
     */
    private void sendResponse404(HttpServletResponse response) {
        //Resource not found
        response.setStatus(HttpServletResponse.SC_NOT_FOUND);
        response.setContentType("text/html");
        try {           
            response.getOutputStream().write("Resource not found".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * Helper method to take care of cleanup
     * @param resource to close
     */
    private  void close(Closeable resource) {
        if (resource != null) {
            try {
                resource.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

}

然后你可以简单地使用它如下

// Force browser to download the resource
    FileDownloadHelper download = new FileDownloadHelper();
    download.write(response, readFileToBytes(pathToFileOnYourFileSystem), FileDownloadHelper.CONTENT_TYPE_PDF,"OUTPUTFILENA.PDF", 
    FileDownloadHelper.CONTENT_DISPOSITION_ATTACHMENT

我希望这会有所帮助并且有意义。缺少一些东西，例如“readFileToBytes”和获取参数，但这应该可以帮助您。

Answer 2

new File(path).toURI().toURL();