Eclipse rcp/rap 开发经验总结(9) - rap上传与下载

 

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一 上传

上传即将文件上传到服务器上，在客户端需要写相应的脚本，服务器端需要注册相应的 handle 接受客户端的请求。

原理：

  Rap 的上传和下载是通过普通的 web 的方式进行上传和下载的 , 但是和传统的 wen 还不相同

1、  rap 本身就单线程在跑 , 和上传下载的线程不能进行混淆

所以采用的方式如下：

上传：通过传统的方式上传到指定目录 ,rap 不能直接操作上传的文件流 , 如果想获得上传的数据必须要先上传到指定文件 , 然后让 rap 去加载指定文件即可

下载： 先通过 rap 程序生成需要下载的文件到指定目录 , 然后通过 rap 加载成文件流的形式发送给客户端

 

1 在服务器端注册相应的 handler

  // 注册上传处理事件

  IServiceManager manager = RWT.getServiceManager ();

  IServiceHandler uploadHandler = new UploadServiceHandler();

manager.registerServiceHandler( "uploadServiceHandler" , uploadHandler); //$NON-NLS-1$

 

2 在客户端的脚本调用

目前的做法是创建上传的 dialog, 在 dialog 里面添加 browser 控件，然后 browser 里书写上传的 javaScript 脚本，脚本请求的 url 格式可以通过以下类似的代码创建：

   private String createUploadUrl(String uploadFileName) {

      StringBuffer url = new StringBuffer();

      url.append(RWT.getRequest ().getContextPath());

      url.append(RWT.getRequest ().getServletPath());

      url.append( "?" ); //$NON-NLS-1$

      url.append(IServiceHandler . REQUEST_PARAM );

      url.append( "=uploadServiceHandler" ); //$NON-NLS-1$

      url.append( "&fileName=" ); //$NON-NLS-1$

      url.append(uploadFileName);

      return url.toString();

   }

3 服务器端 handler 的写法

public class UploadServiceHandler implements IServiceHandler {

   public void service() throws IOException, ServletException {

      HttpServletRequest request = RWT.getRequest ();

      request.setCharacterEncoding( "UTF-8" );

      String fileName = request.getParameter( "fileName" );

      FileOutputStream o = null ;

      BufferedReader bufferReader = null ;

      InputStream in = null ;

      try {

         in = request.getInputStream();

         File f = null ;

         try {

          f = new File(FileUtil.getTempFilePathAndName (RWT.getRequest ()

            .getSession().getAttribute( "userName" ).toString(),

                   fileName));

         } catch (Exception e) {

            throw new IOException(e);

         }

         o = new FileOutputStream(f);

         bufferReader = new BufferedReader( new InputStreamReader(in));

         String line = null ;

         boolean beginWrite = false ;

         boolean endWrite = false ;

         while ((line = bufferReader.readLine()) != null ) {

            if (line.indexOf(PriceDomainBean. class .getName()) != -1) {

                if (!beginWrite) {

                   beginWrite = true ;

                } else {

                   endWrite = true ;

                }

            }

            if (beginWrite) {

                o.write((line + "\r\n" ).getBytes());

            }

            if (endWrite) {

                break ;

            }

         }

      } catch (IOException e) {

         throw e;

      } finally {

         if ( null != o) {

            o.close();

         }

         in.close();

         if ( null != bufferReader) {

            bufferReader.close();

         }

      }

      HttpServletResponse response = RWT.getResponse ();

      response.setContentType( "text/html;charset=UTF-8" );

      response.getWriter().write(

            "<br><br><br><DIV align=center><h2> 上传成功 !</h2>" );

   }

}

二 下载

下载和上传采用的方式基本相同，只不过是将服务器文件读取到本地，和上传是一个相反的过程。

1 在服务器端注册相应的 handler

  // 注册下载处理事件

  IServiceManager manager = RWT.getServiceManager ();

  IServiceHandler downloadHandler = new DownloadServiceHandler();

  manager.registerServiceHandler( "downloadServiceHandler" , downloadHandler);

 

2 在客户端节本的调用

在 bowser 控件中书写 js 请求脚本，脚本请求的 url 如下

    private String createDownloadUrl(String fileName) {

        StringBuffer url = new StringBuffer();

        url.append (RWT.getRequest ().getContextPath());

        url.append (RWT.getRequest ().getServletPath());

        url.append ( "?" );

        url.append (IServiceHandler. REQUEST_PARAM );

        url.append ( "=downloadServiceHandler" );

        url.append ( "&fileName='+encodeURI('" );

        url.append (fileName);

        url.append ( "')" );

        return url.toString();

    }

3 服务器端 handler 的写法

public class DownloadServiceHandler implements IServiceHandler {

   public void service() throws IOException, ServletException {

      String fileName = URLDecoder.decode (

            RWT.getRequest ().getParameter( "fileName" ), "UTF-8" );

      String filePathAndName = null ;

      try {

         filePathAndName = FileUtil

         .getTempFilePathAndName (RWT.getRequest ().getSession()

                      .getAttribute( "userName" ).toString(), fileName);

      } catch (Exception e) {

         throw new IOException(e);

      }

      File file = new File(filePathAndName);

      if (!file.exists()) {

         return ;

      }

      HttpServletResponse response = RWT.getResponse ();

      response.setHeader( "pragma" , "no-cache" );

      response.setHeader( "cache-control" , "no-cache" );

      response.setDateHeader( "Expires" , 0);

      response.setCharacterEncoding( "UTF-8" );

      response.setContentType( "text/html;charset=UTF-8" );

      response.setHeader( "Content-Disposition" , "attachment;filename="

            + new String(fileName.getBytes( "gb2312" ), "ISO8859-1" ));

      try {

         BufferedInputStream in = new BufferedInputStream(

                new FileInputStream(filePathAndName));

         ByteArrayOutputStream out = new ByteArrayOutputStream(1024);

         byte [] temp = new byte [1024];

         int size = 0;

         while ((size = in.read(temp)) != -1) {

            out.write(temp, 0, size);

         }

         in.close();

         byte [] content = out.toByteArray();

         response.setContentLength(content. length );

         response.getOutputStream().write(content);

      } catch (IOException ioe) {

         throw new RuntimeException(ioe);

      } finally {

         try {

            FileUtil.deleteTempFile (RWT.getRequest ().getSession()

                   .getAttribute( "userName" ).toString(), fileName);

         } catch (Exception e) {

            throw new IOException(e);

         }

      }

   }

}