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--- jvx:code_snippets [2018/02/06 10:09]
admin
+++ jvx:code_snippets [2018/02/06 10:17]
admin
@@ Line 1: / Line 1: @@
 ~~NOTRANS~~
+~~Title: JVx code snippets~~
 We have a list of useful code snippets for you. Simply use them for your application. All snippets are free to use and licensed under [[https://www.apache.org/licenses/LICENSE-2.0|Apache 2.0]].
@@ Line 42: / Line 43: @@
 Sometimes we need an application without overhead, e.g for Vaadin UI.
-<file java>
+<file java SimpleApplication.java>
 public class SimpleApplication extends Application
                                implements IExceptionListener
@@ Line 115: / Line 116: @@
 }   // SimpleApplication
 </file>
+==== Test your business logic with JUnit ====
+Tests our business logic without an application server, but with our Lifecycle objects. We test our server code without specific configuration or modifications for unit tests.
+Business Object:
+<file java UserRegistration.java>
+public class UserRegistration
+{
+   /**
+    * Removes/Unregisters a user and all its content.
+    *
+    * @param pUserName the user name
+    * @throws Exception if the user can not be deleted
+    */
+   public void delete(String pUserName) throws Exception
+   {
+      try
+      {
+         DBAccess dba = (DBAccess)SessionContext.getCurrentSession().get("newDBAccess");
+         DBStorage dbsUser = new DBStorage();
+         dbsUser.setDBAccess(dba);
+         dbsUser.setWritebackTable("USERS");
+         dbsUser.open();
+         List<IBean> liBeans = dbsUser.fetchBean(new Equals("USERNAME",
+                                                            pUserName), null, 0, -1);
+         //the username is unique and it's not possible that a user exists
+         //more than once!
+         if (liBeans.size() == 1)
+         {
+            //delete the user (db will cascade all user-data)
+            dbsUser.delete(liBeans.get(0));
+         }
+         else
+         {
+            throw new SecurityException("User '" + pUserName + "' was not found!");
+         }
+      }
+      catch (Throwable th)
+      {
+         throw new SecurityException("It's not possible to delete the user!", th);
+      }
+   }
+}   // UserRegistration
+</file>
+A standard Lifecycle Object:
+<file java Session.java>
+public class Session extends GenericBean
+{
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   // User-defined methods
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   /**
+    * Creates a new database access object.
+    *
+    * @return the new database access object
+    * @throws Exception if the connection can not be opened
+    */
+   public DBAccess getNewDBAccess() throws Exception
+   {
+      DBAccess dba = DBAccess.getDBAccess(DBSecurityManager.getCredentials(
+                                          SessionContext.getCurrentSessionConfig()));
+      dba.open();
+      return dba;
+   }
+   /**
+    * Returns the access to the database.
+    *
+    * @return the access to the database
+    * @throws Exception if the datasource can not be opened
+    */
+   public DBAccess getDBAccess() throws Exception
+   {
+      DBAccess dba = (DBAccess)get("dBAccess");
+      if (dba == null)
+      {
+         dba = getNewDBAccess();
+         put("dBAccess", dba);
+      }
+      return dba;
+   }
+   /**
+    * Gets the user registration business object.
+    *
+    * @return the business object for user registrations
+    */
+   public UserRegistration getRegistration()
+   {
+      UserRegistration ureg = (UserRegistration)get("registration");
+      if (ureg == null)
+      {
+         ureg = new UserRegistration();
+         put("registration", ureg);
+      }
+      return ureg;
+   }
+}    // Session
+</file>
+Unit Test:
+<file java>
+/**
+ * Tests the our delete method from the user registration object.
+ *
+ * @throws Throwable if the test fails
+ */
+@Test
+public void testDelete() throws Throwable
+{
+   AbstractConnection con = createConnection(null);
+   try
+   {
+      //delete user with the name "unknownuser"
+      con.call("registration", "delete", "unknownuser");
+      Assert.fail("User 'unknownuser' found!");
+   }
+   catch (SecurityException se)
+   {
+      Assert.assertEquals("User 'unknownuser' was not found!",
+                          se.getMessage());
+   }
+   con.close();
+}
+/**
+ * Creates a new connection.
+ *
+ * @param pConProps additional connection properties
+ * @return the connection
+ * @throws Throwable if the connection can not be opened
+ */
+private AbstractConnection createConnection(Hashtable<String, String> pConProps) throws Throwable
+{
+   MasterConnection macon = new MasterConnection(new DirectServerConnection());
+   macon.setApplicationName("app");
+   macon.setUserName("user");
+   macon.setPassword("pwd");
+   if (pConProps != null)
+   {
+      for (Map.Entry<String, String> entry : pConProps.entrySet())
+      {
+         macon.setProperty(entry.getKey(), entry.getValue());
+      }
+   }
+   macon.open();
+   return macon;
+}
+</file>
+==== A very simple AbstractMemStorage implementation ====
+A server side memory storage with the column names: ID, NAME, PATH. The column PATH is not visible on the client-side, but is important for server-side. If "error" is set as NAME, an Exception is thrown!
+<file java SimpleMemStorage.java>
+public class SimpleMemStorage extends AbstractMemStorage
+{
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   // Abstract methods implementation
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   /**
+    * {@inheritDoc}
+    */
+   @Override
+   public RowDefinition getRowDefinition() throws ModelException
+   {
+      RowDefinition rowdef = new RowDefinition();
+      rowdef.addColumnDefinition(new ColumnDefinition("ID", new BigDecimalDataType()));
+      rowdef.addColumnDefinition(new ColumnDefinition("NAME", new StringDataType()));
+      rowdef.addColumnDefinition(new ColumnDefinition("PATH", new StringDataType()));
+      rowdef.setPrimaryKeyColumnNames(new String[] {"ID"});
+      rowdef.setColumnView(null, new ColumnView("ID", "NAME"));
+      return rowdef;
+   }
+   /**
+    * {@inheritDoc}
+    */
+   @Override
+   public void loadData(MemDataBook pBook, ICondition pFilter) throws ModelException
+   {
+      pBook.deleteAllDataRows();
+      pBook.insert(false);
+      pBook.setValues(new String[] {"ID", "NAME", "PATH"},
+                      new Object[] {BigDecimal.valueOf(0), "First", "/home/first"});
+      pBook.insert(false);
+      pBook.setValues(new String[] {"ID", "NAME", "PATH"},
+                      new Object[] {BigDecimal.valueOf(1), "Second", "/home/second"});
+      pBook.insert(false);
+      pBook.setValues(new String[] {"ID", "NAME", "PATH"},
+                      new Object[] {BigDecimal.valueOf(2), "Third", "/home/third"});
+   }
+   /**
+    * {@inheritDoc}
+    */
+   @Override
+   public void insert(DataBookEvent pEvent) throws ModelException
+   {
+      if ("error".equals(pEvent.getChangedDataBook().getValueAsString("NAME")))
+      {
+         throw new ModelException("not allowed");
+      }
+   }
+   @Override
+   public void delete(DataBookEvent pEvent)
+   {
+   }
+   @Override
+   public void update(DataBookEvent pEvent) throws ModelException
+   {
+      if ("error".equals(pEvent.getChangedDataBook().getValueAsString("NAME")))
+      {
+         throw new ModelException("not allowed");
+      }
+   }
+}   // SimpleMemStorage
+</file>
+==== Change XML files very fast ====
+Our XML file
+<file xml>
+<server>
+  <!-- Test: STARTPORT -->
+  <startport>2001</startport>
+  <audio>off</audio>
+  <serial>COM1</serial>
+  <domain>JVx</domain>
+</server>
+</file>
+Change it:
+<file java>
+XmlNode xmnRead = readXml("simple.xml");
+xmnRead.setNode("/server/audio", null);
+xmnRead.setNode("/server/domain", "www.sibvisions.com");
+writeXml(xmnRead, "simple.xml");
+</file>
+==== EventHandler without Listener interface ====
+Event definition:
+<file java>
+/** the event handler for captured (the event has one parameter: byte[]). */
+private CallableHandler chCaptured = new CallableHandler(byte[].class);
+/** the event handler for canceled (the event has no parameter). */
+private CallableHandler chCanceled = new CallableHandler();
+</file>
+Event access:
+<file java>
+/**
+ * Gets the captured event handler.
+ *
+ * @return the event handler
+ */
+public CallableHandler eventCaptured()
+{
+   return chCaptured;
+}
+/**
+ * Gets the canceled event handler.
+ *
+ * @return the event handler
+ */
+public CallableHandler eventCanceled()
+{
+   return chCanceled;
+}
+</file>
+Dispatch events:
+<file java>
+chCaptured.dispatchEvent(byData);
+chCancel.dispatchEvent();
+</file>
+Listener registration:
+<file java>
+object.eventCaptured().addListener(this, "doCapture");
+public void doCapture(byte[] pImage) throws Exception
+{
+    //...
+}
+</file>
+==== EventHandler with Listener interface ====
+The interface:
+<file java IRemoteApplicationListener.java>
+public interface IRemoteApplicationListener
+{
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   // Method definitions
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+    /**
+     * Invoked when login was successful.
+     *
+     * @param pApplication the application
+     */
+    public void afterLogin(RemoteApplication pApplication);
+    /**
+     * Invoked when logout was successful.
+     *
+     * @param pApplication the application
+     */
+    public void afterLogout(RemoteApplication pApplication);
+}   // IRemoteApplicationListener
+</file>
+The EventHandler:
+<file java RemoteApplicationHandler.java>
+public class RemoteApplicationHandler extends RuntimeEventHandler<IRemoteApplicationListener>
+{
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   // Initialization
+   //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   /**
+    * Constructs a new RemoteApplicationHandler.
+    *
+    * @param pListenerMethodName the method to be called inside the interface.
+    */
+   public RemoteApplicationHandler(String pListenerMethodName)
+   {
+      super(IRemoteApplicationListener.class, pListenerMethodName);
+   }
+}   // RemoteApplicationHandler
+</file>
+Event access:
+<file java>
+/** the "after login" event. */
+private RemoteApplicationHandler eventAfterLogin;
+/** the "after logout" event. */
+private RemoteApplicationHandler eventAfterLogout;
+/**
+ * Gets the event handler for the after login event.
+ *
+ * @return the event handler
+ */
+public RemoteApplicationHandler eventAfterLogin()
+{
+   if (eventAfterLogin == null)
+   {
+      eventAfterLogin = new RemoteApplicationHandler("afterLogin");
+   }
+   return eventAfterLogin;
+}
+/**
+ * Gets the event handler for the after logout event.
+ *
+ * @return the event handler
+ */
+public RemoteApplicationHandler eventAfterLogout()
+{
+   if (eventAfterLogout == null)
+   {
+      eventAfterLogout = new RemoteApplicationHandler("afterLogout");
+   }
+   return eventAfterLogout;
+}
+</file>
+Dispatch Events:
+<file java>
+/**
+ * Fires the after logout event.
+ */
+protected void afterLogout()
+{
+   if (eventAfterLogout != null)
+   {
+      eventAfterLogout.dispatchEvent(this);
+   }
+}
+/**
+ * Fires the after login event.
+ */
+protected void afterLogin()
+{
+   if (eventAfterLogin != null)
+   {
+      eventAfterLogin.dispatchEvent(this);
+   }
+}
+</file>
+Listener registration:
+<file java>
+app.eventAfterLogin().addListener(this, "doAfterLogin");
+app.eventAfterLogout().addListener(this, "doAfterLogout");
+//We do not need the parameter
+public void doAfterLogin()
+{
+}
+//We do not need the parameter
+public void doAfterLogout()
+{
+}
+</file>