Question

我正在使用GWT。

我必须从服务器下载文件文件到客户端。

文档位于外部存储库中。

客户端通过Servlet发送文档的id。

在服务器端：检索使用此ID文档：

Document document = (Document)session.getObject(docId);
ContentStream contentStream = document.getContentStream();

ByteArrayInputStream inputStream = (ByteArrayInputStream) contentStream.getStream();

int c;
while ((c = inputStream.read()) != -1) {
    System.out.print((char) c); 
}
String mime = contentStream.getMimeType();
String name = contentStream.getFileName();
InputStream strm = contentStream.getStream();

我可以在这里阅读该文件。

我想将此邮件发送给客户。如何将其作为文件并将其发送回客户端？

Answer 1

在你的Servlet中：

Document document =(Document)session.getObject(docId);
ContentStream contentStream = document.getContentStream();
String name = contentStream.getFileName();
response.setHeader("Content-Type", "application/octet-stream;");
response.setHeader("Content-Disposition", "attachment;filename=\"" + name + "\"");
OutputStream os = response.getOutputStream();
InputStream is = 
  (ByteArrayInputStream) contentStream.getStream();
BufferedInputStream buf = new BufferedInputStream(is);
int readBytes=0;
while((readBytes=buf.read())!=-1) {
      os.write(readBytes);
}   
os.flush();
os.close();// *important*
return;

Answer 2

您可以在服务器端创建标准servlet（扩展HttpServlet而不是RemoteServiceServlet），并在客户端提交id作为servlet参数。

现在您需要在获取请求后创建excel文件并将其发送到客户端。浏览器显示自动弹出下载对话框。但是您应该确保设置正确的内容类型响应标头。此标头将指示浏览器是哪种类型的文件。

protected void doGet(HttpServletRequest request, HttpServletResponse response) 
                                              throws ServletException, IOException { 

String fileId = reguest.getParameter("fileId"); // value of file id from request
File file = CreatorExel.getFile(fileId); // your method to create file from helper class

// setting response headers
response.setHeader("Content-Type", getServletContext().getMimeType(file.getName())); 
response.setHeader("Content-Length", file.length()); 
response.setHeader("Content-Disposition", "inline; filename=\"" + file.getName() + "\""); 

BufferedInputStream input = null; 
BufferedOutputStream output = null; 

try { 
    InputStream inputStream = new FileInputStream(file);
    ServletOutputStream outputStream = response.getOutputStream();

    input = new BufferedInputStream(fileInput); 
    output = new BufferedOutputStream(outputStream); 

    int count;
    byte[] buffer = new byte[8192]; //  buffer size is 512*16
    while ((count = input.read(buffer)) > 0) {
         output.write(buffer, 0, count);
    }

} finally { 
    if (output != null) {
       try { 
          output.close(); 
       } catch (IOException ex) {
       } 
    }
    if (input != null) {
       try { 
          input.close(); 
       } catch (IOException ex) {
       } 
    } 
}

在GWT中将文件从服务器发送到客户端

2 个答案: