log4j Configuration

Step1:  Add dependency in pom.xml file.

Step2:  Need to add below logger code snippet in log4j2.xml file in your application.

Step3: Need to change as below code snippet in applicationContext.xml in your application.

 Step 4: Restart the server and check the console.

Struts 1 and 2 Architectures

Struts Architecture 

Step 1: User Sends the request to Action Servlet.
Step 2: Struts-config.xml contains the Actions, Forms, ActionForwards and Mappings.
Step 3: Bundle all the request into a JavaBean extends the ActionForm.
Step 4: Decides which action class invokes to process the request.
Step 5: Vallidate the data.
Step 6: Action Class process the request with the help of ModelComponent.
Step 7: The Model interacts with DB and process the request.
Step 8: Completing the request process by Action class and returns the ActionForward to the controller.
Step 9: Based on ActionForward the controller will invoke the Appropriate View.
Step 10: Response with render back to View Component.

Struts 2 Architecture 

Step 1: User sends the request to the container.

Step 2: Container call the web.xml file and get the controller name.

Step 3: Controller calls the ActionMapper and gets the action.

Step 4: Based on action it will call the Action Proxy 

Step 5: Action proxy will call the Configuration manager which in struts.xml file to get the info of action.

Step 6: Action Proxy process the request to Action Invocation.

Step 7: Action Invocations invokes all Interceptors and call the Action.

Step 8: Based on Action result (Response) will generate through the Action Invocation.

Step 9: Through the HttpServletResponse will sent the result to the End user.

JDBC Connection Steps

Jdbc Connection: 
Step 1: Loading the driver
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Step 2: Preparing the Connection String
            String cs = "jdbc:odbc:dsnName";
Step 3: Request for the connection
            Connection con = DriverManager.getConnection(cs,"username","password");
Step 4: Perform the dml operations
            Statement stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery("select * from Employee");
Step 4: Storing the Results in Result Set
            while(rs.next())
            { rs.getInt(1); rs.getString(2);rs.getDouble(3);}
Step 5: Close the all open connections.
             rs.close(); st.close(); con.close();

PreparedStatement in JDBC:
Step 1 & 2 & 3 are same
Step 4: PreparedStatement is used to store the data dynamically. We can execute the SQL statements             multiple times using paramaterized statements.
            String insertps = con.prepareStatement("insert into Employee values(?,?,?)");
            String updateps = con.prepareStatement("update Employee set name = ?, address = ?, salary                =?");
            String deleteps = con.prepareStatement("delete Employee where salary =?");
            String selectps = con.prepareStatement("select * from Employee where EmpNo = ?");
Step 5: For all above statements set the parameters using setXXX and send
            insertps.setString(1,EmpNo);
            insertps.setString(2,Address);
            insertps.setDouble(3,Salary);
Step 6: Like above we can delete and update all the PreparedStaments.
Step 7: Finally Close the connections.