要上传的文件,我已经在过去延长了HttpServlet。我与Commons-FileUpload一起使用它。
我做了一个基于窗体的上传的常用小部件。这是为了适应不同文件类型(纯文本和Base64)的上传。如果您只需要上传纯文本文件,则可以将以下两个类合并为一个。
public class UploadFile extends Composite {
@UiField FormPanel uploadForm;
@UiField FileUpload fileUpload;
@UiField Button uploadButton;
interface Binder extends UiBinder<Widget, UploadFile> {}
public UploadFile() {
initWidget(GWT.<Binder> create(Binder.class).createAndBindUi(this));
fileUpload.setName("fileUpload");
uploadForm.setEncoding(FormPanel.ENCODING_MULTIPART);
uploadForm.setMethod(FormPanel.METHOD_POST);
uploadForm.addSubmitHandler(new SubmitHandler() {
@Override
public void onSubmit(SubmitEvent event) {
if ("".equals(fileUpload.getFilename())) {
Window.alert("No file selected");
event.cancel();
}
}
});
uploadButton.addClickHandler(new ClickHandler() {
@Override
public void onClick(ClickEvent event) {
uploadForm.submit();
}
});
}
public HandlerRegistration addCompletedCallback(
final AsyncCallback<String> callback) {
return uploadForm.addSubmitCompleteHandler(new SubmitCompleteHandler() {
@Override
public void onSubmitComplete(SubmitCompleteEvent event) {
callback.onSuccess(event.getResults());
}
});
}
}
UiBinder部分非常直观。
<g:HTMLPanel>
<g:HorizontalPanel>
<g:FormPanel ui:field="uploadForm">
<g:FileUpload ui:field="fileUpload"></g:FileUpload>
</g:FormPanel>
<g:Button ui:field="uploadButton">Upload File</g:Button>
</g:HorizontalPanel>
</g:HTMLPanel>
现在你可以扩展这个类的纯文本文件。只要确保您的web.xml
在/textupload
服务于HttpServlet。
public class UploadFileAsText extends UploadFile {
public UploadFileAsText() {
uploadForm.setAction(GWT.getModuleBaseURL() + "textupload");
}
}
纯文本文件的servlet放在服务器端。它将上传文件的内容返回给客户端。确保从你的类路径的某处安装Apache Commons的FileUpload jar。
public class TextFileUploadServiceImpl extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
if (! ServletFileUpload.isMultipartContent(request)) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Not a multipart request");
return;
}
ServletFileUpload upload = new ServletFileUpload(); // from Commons
try {
FileItemIterator iter = upload.getItemIterator(request);
if (iter.hasNext()) {
FileItemStream fileItem = iter.next();
// String name = fileItem.getFieldName(); // file name, if you need it
ServletOutputStream out = response.getOutputStream();
response.setBufferSize(32768);
int bufSize = response.getBufferSize();
byte[] buffer = new byte[bufSize];
InputStream in = fileItem.openStream();
BufferedInputStream bis = new BufferedInputStream(in, bufSize);
long length = 0;
int bytes;
while ((bytes = bis.read(buffer, 0, bufSize)) >= 0) {
out.write(buffer, 0, bytes);
length += bytes;
}
response.setContentType("text/html");
response.setContentLength(
(length > 0 && length <= Integer.MAX_VALUE) ? (int) length : 0);
bis.close();
in.close();
out.flush();
out.close();
}
} catch(Exception caught) {
throw new RuntimeException(caught);
}
}
}
我不记得我是如何解决<pre></pre>
标记问题的。您可能必须过滤客户端上的标签。该主题也被编为here。