Session Management (Set and Get Data from Session) in GWT

When you think about the Security of a web application 'Session Management' is the first thing that strikes in your head. I am now working with an enterprise web application using GWT and you know security is a very vital issue in an enterprise application. And we have ensured the security by managing session data. Here i will describe how to store and retrieve data from session by using GWT RPC.

Suppose you want to store the user name in session after login to the application and check the session value later. Then what do you do?

First create a GWT RPC Service named 'SessionManagementService'. You can give any other name as you like. In SessionManagementService interface add two methods

public void setUserName(String userName);
public String getUserName();

And synchronize the methods with 'SessionManagementServiceAsync'.

public void setUserName(String userName, AsyncCallback<Void> asyncCallback);
public void getUserName(AsyncCallback<String> asyncCallback);

Now implement the methods in 'SessionManagementServiceImpl'. Let's first talk about the setter method.

public void setUserName(String userName)
{
     HttpSession httpSession = getThreadLocalRequest().getSession(true);
     httpSession.setAttribute("userName", userName);
}

The getThreadLocalRequest method returns you a HttpServletRequest object for the current call. For simultaneous invocation you will get different request object. And the getSession method returns you the current HttpSession for the associated request. So you can get the current session of the current call by getThreadLocalRequest().getSession(true).

The setAttribute method binds an object to the associated session. It stores the object's value as a Name-Value pair. You can put any thing as the value of the object. A String value or List<String> any thing. Here the name of the object is "useName" and the object is bound to this session with this name.

Now come to the getter method.

public String getUserName()
{
    HttpSession session = getThreadLocalRequest().getSession(true);
    if (session.getAttribute("userName") != null)
    {
        return (String) session.getAttribute("userName");
    }
    else 
    {
        return "";
    }
}

Get the current session in the same way as described for the setter method. The getAttribute method returns the value of the object which is bound with this session with the specific name. Then simply cast it with your desired type.

Thats all. Just call the services according to your requirement. Play with GWT and stay in touched. :-D

How to Create an Editable TreeGrid in GXT(Ext GWT)

In our project I need to add the editable functionality with the GXT TreeGrid. Here I am going to share my experience about how to create an editable TreeGrid.

You may have already known that to build a TreeGrid the tree node objects must possess the functionality of BaseTreeModel of GXT. I have used the same EmployeeTreeNode and Folder class for leaf and parent nodes that i used in my previous blogs about GXT TreePanel. And in the TestData class i have populated the data to build the TreeGrid. You will find the code for these classes here.
(If you are new in GWT and GXT read my blogs about creating a new project in gwt and add GXT library)

First create a root object named model of the Folder class from TestData.getTreeModel() method.

Folder model = TestData.getTreeModel();

Then create a TreeStore object,store from this model and add data to the store

TreeStore<ModelData> store = new TreeStore<ModelData>();
store.add(model.getChildren(), true);

Now the time for defining ColumnConfig objects. First create a ColumnConfig, name and set a TextField as the editor of this object.

ColumnConfig name = new ColumnConfig("name", "Name", 100);
name.setRenderer(new TreeGridCellRenderer<ModelData>());
TextField<String> text = new TextField<String>();
text.setAllowBlank(false);
name.setEditor(new CellEditor(text));

The second column is the salary column so you can set a NumberField as the editor for this column.

ColumnConfig salary = new ColumnConfig("salary", "Salary", 100);
salary.setEditor(new CellEditor(new NumberField()));

In my example the third column is the joining date column. So you have to set a DateField as the editor for this column. For this first create a DateField object dateField and set the display format of the field. Then create a ColumnConfig object date and set the dateField as the editor of the date.

DateField dateField = new DateField();  
dateField.getPropertyEditor().setFormat(DateTimeFormat.getFormat("MM/dd/y"));
     
ColumnConfig date = new ColumnConfig("joiningdate", "Joining Date", 100); 
date.setAlignment(HorizontalAlignment.RIGHT);
date.setEditor(new CellEditor(dateField));  
date.setDateTimeFormat(DateTimeFormat.getMediumDateFormat());

Now create a ColumnModel from these three ColumnConfig objects.

ColumnModel cm = new ColumnModel(Arrays.asList(name, salary, date));

From the ColumnModel and TreeStore create an EditorTreeGrid object and set some property of the object.

EditorTreeGrid<ModelData> editorTreeGrid = new EditorTreeGrid<ModelData>(store,cm);
editorTreeGrid.setClicksToEdit(ClicksToEdit.TWO);
editorTreeGrid.setBorders(true);
editorTreeGrid.setSize(400, 400);
editorTreeGrid.setAutoExpandColumn("name");
editorTreeGrid.setTrackMouseOver(false);

The setter methods are self explanatory.

Finally create a ContentPanel and add the editorTreeGrid in this panel.

ContentPanel cp = new ContentPanel();
cp.setBodyBorder(false);
cp.setHeading("Cell TreeGrid Editing (2-Clicks)");
cp.setButtonAlign(HorizontalAlignment.CENTER);
cp.setLayout(new FitLayout());
cp.setFrame(true);
cp.setSize(600, 300);
cp.add(editorTreeGrid);
RootPanel.get().add(cp);

To view the live demo of this tutorial Click here.
The output will be like this