在Java Desktop
应用程序中,我们可以允许用户将文件上传到WebServer中的文件夹中,就像这样
File rootDir = new File( "/home/bala/temp" ) ;
if( FileUpload.isMultipartContent( request ) ) {
DiskFileUpload fileUpload = new DiskFileUpload() ;
Iterator iterator = fileUpload.parseRequest( request ).iterator() ;
while( iterator.hasNext() ) {
FileItem fileItem = ( FileItem ) iterator.next() ;
File file = new File( rootDir , fileItem.getName() ) ;
fileItem.write( file ) ; }
}
else { throw new Exception( "Invalid request " ) ; }
但是我们如何在Gwt或GWTP中做到这一点呢?Gwt是否包含任何支持此功能的类? 我会使用gwupload,因为它很简单。
在客户端使用Multiuploader如果你想上传多个文件:
public void onModuleLoad() {
MultiUploader uploader = new MultiUploader();
RootPanel.get().add(uploader);
uploader.addOnFinishUploadHandler(new IUploader.OnFinishUploaderHandler() {
public void onFinish(IUploader uploader) {
if (uploader.getStatus() == Status.SUCCESS) {
UploadedInfo info = uploader.getServerInfo();
System.out.println("File name " + info.name);
System.out.println("File content-type " + info.ctype);
System.out.println("File size " + info.size);
}
}
});
}
在服务器端,只需覆盖库提供的UploadAction
servlet。
编辑:注意该方法接收FileItem
的列表,每个FileItem是上传文件的临时信息和内容,而不是真正的java File
。这里是您放置业务代码的地方,以创建自己的dirs
结构,处理它们,甚至将它们存储为ddbb中的blob字段。在这种情况下,我们将获取所有文件并将它们存储在临时文件夹中(注意,这个文件夹在linux, windows等中是不同的)。
public class SampleUploadServlet extends UploadAction {
@Override
public String executeAction(HttpServletRequest request, List<FileItem> sessionFiles) throws UploadActionException {
String response = "";
for (FileItem item : sessionFiles) {
if ( ! item.isFormField()) {
try {
File file = File.createTempFile("upload-", ".bin");
item.write(file);
/// Send a customized message to the client.
response += file.getAbsolutePath() + "n";
} catch (Exception e) {
throw new UploadActionException(e);
}
}
}
/// Remove files from session because we have a copy of them
removeSessionFileItems(request);
/// Send your customized message to the client.
return response;
}
}
如果您的servlet已经处理多部分请求,您可以使用GWT中的标准方式使用FileUpload
和FormPanel
,尽管您将错过进度条,文件选择器样式等。
// Add a form-panel to your document
final FormPanel form = new FormPanel();
form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);
form.setAction("your_upload_servlet_url");
RootPanel.get().add(form);
// Add a file-upload to your form
FileUpload fu = new FileUpload();
form.add(fu);
// submit your form when the user selects a file
fu.addChangeHandler(new ChangeHandler() {
public void onChange(ChangeEvent event) {
form.submit();
}
});