Eclipse rcp/rap 开发经验总结(九) - rap上传与下载
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);
}
}
}
}