Google Guava 库用法整理

http://macrochen.iteye.com/blog/737058

MySQL JDBC

 

 

Driver:  com.mysql.jdbc.Driver

URL: jdbc:mysql://localhost:3306/test?useUnicode=true

A Vaadin resource for the blobstore

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

public class BlobstoreResource implements ApplicationResource { // variables skipped public BlobstoreResource(String keyStr, Application application) { this.application = application; this.blobKey = new BlobKey(keyStr); this.blobInfo = new BlobInfoFactory().loadBlobInfo(blobKey); if (blobInfo == null) ; // handle missing blob here application.addResource(this); }   @Override public String getMIMEType() { return blobInfo.getContentType(); }   @Override public DownloadStream getStream() { InputStream inputStream; try { inputStream = new BlobstoreInputStream(blobKey); } catch (IOException e) { return null; }   final DownloadStream ds = new DownloadStream(inputStream, getMIMEType(), getFilename()); ds.setBufferSize(getBufferSize()); ds.setCacheTime(cacheTime); return ds; }   // other methods skipped ... }

Vaadin refresh parameter handler

@Override
public void handleParameters(Map<String, String[]> parameters) {
  if(parameters.containsKey("refresh")) {
    // refresh the layout ...
  }
}

1 2 3 4 5 6 7 8 9 10 11 12 13

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { final Map blobs = blobstoreService.getUploadedBlobs(req); final BlobKey blobKey = blobs.get("myImage"); final String uploadKey = req.getParameter("uploadKey");   final Objectify ofy = ObjectifyService.begin(); final User user = ofy.query(User.class).filter("uploadKey", uploadKey).get(); user.setBlobKey(blobKey.getKeyString()); ofy.put(user);   resp.sendRedirect("/?refresh"); }

Get Http Request Object

Vaadin "transaction" equals "http request".

 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

/**
     * Vaadin "transaction" equals "http request".  This method fires for all servlets
     * in the session.
     */
    private void attachHttpRequestListener() {
        getContext().addTransactionListener(new TransactionListener() {
            private static final long serialVersionUID = -2365336986843262181L;

            public void transactionStart(Application application,
                    Object transactionData) {
                ((LocalizedSystemMessages)getSystemMessages()).setThreadLocale(getLocale());
                current.set(CompetitionApplication.this);  // make the application available via ThreadLocal
                HttpServletRequest request = (HttpServletRequest)transactionData;
                request.getSession(true).setMaxInactiveInterval(3600);
            }
            
            public void transactionEnd(Application application,
                    Object transactionData) {
                // Transaction listener gets fired for all (Http) sessions
                // of Vaadin applications, checking to be this one.
                if (application == CompetitionApplication.this) {
                    closeHibernateSession();
                }
            }
        });
    }