GWT - Hibernate: How to display results from MySQL into GWT client - mysql

Question

I am very starter to GWT and Hibernate. I made a simple GWT RPC application that adds a user to MySQL using Hibernate. I declared a single method in service interface i.e. addUser that adds a user(i.e. firstName & LastName) to MySQL calling Hibernate method. Its is working fine. Now added a 2nd method to retrieve users from DB & display.
Here are service interfaces
service interfaces
package rpctest.client;
import java.util.ArrayList;
import hibDomain.User;
import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;
#RemoteServiceRelativePath("testService")
public interface RpctestService extends RemoteService {
public String addUser(String firstName,String lastName) throws
llegalArgumentException;
public ArrayList<User> getUser();
}
-------------------------------------
package rpctest.client;
import java.util.ArrayList;
import hibDomain.User;
import com.google.gwt.user.client.rpc.AsyncCallback;
public interface RpctestServiceAsync {
void addUser(String firstName, String lastName,
AsyncCallback<String> callback);
void getUser(AsyncCallback<ArrayList<User>> asyncCallback);
}
Here is entry point class
package rpctest.client;
import java.util.ArrayList;
import hibDomain.User;
import rpctest.shared.FieldVerifier;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyPressEvent;
import com.google.gwt.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyPressEvent;
import com.google.gwt.event.dom.client.KeyPressHandler;
/**
* Entry point classes define <code>onModuleLoad()</code>.
*/
public class Rpctest implements EntryPoint {
final TextBox firstName = new TextBox();
final TextBox lastName = new TextBox();
final Button ans = new Button("Add User");
//final Label label1 = new Label("First Name");
//final Label label2 = new Label("Last Name");
private FlexTable userFlexTable = new FlexTable();
//final Label errorLabel = new Label();
private VerticalPanel mainpanel = new VerticalPanel();
private HorizontalPanel addpanel1 = new HorizontalPanel();
private HorizontalPanel addpanel2 = new HorizontalPanel();
private final RpctestServiceAsync calNumbers = GWT
.create(RpctestService.class);
/**
* This is the entry point method.
*/
public void onModuleLoad() {
userFlexTable.setText(0, 0, "User ID");
userFlexTable.setText(0, 1, "First Name");
userFlexTable.setText(0, 2, "Second Name");
userFlexTable.setText(0, 3, "Remove");
//add input boxes to panel
addpanel1.add(firstName);
addpanel1.add(lastName);
firstName.setFocus(true);
//add input
mainpanel.add(userFlexTable);
mainpanel.add(addpanel1);
addpanel1.add(ans);
ans.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
addStock();
}
});
lastName.addKeyPressHandler(new KeyPressHandler() {
public void onKeyPress(KeyPressEvent event) {
if (event.getCharCode() == KeyCodes.KEY_ENTER) {
addStock();
}
}
});
RootPanel.get().add(mainpanel);
}
private void addStock(){
String name1 = firstName.getValue();
// Stock code must be between 1 and 10 chars that are numbers, letters, or dots.
/*if (!name1.matches("^[0-9A-Z\\.]{1,10}$")) {
Window.alert("'" + name1 + "' is not a valid name.");
firstName.selectAll();
return;
}*/
firstName.setValue("");
String name2 = lastName.getValue();
/*if (!name2.matches("^[0-9A-Z\\.]{1,10}$")) {
Window.alert("'" + name1 + "' is not a valid name.");
lastName.selectAll();
return;
}*/
lastName.setValue("");
firstName.setFocus(true);
calNumbers.addUser(name1,name2,
new AsyncCallback<String>() {
public void onFailure(Throwable caught) {
// Show the RPC error message to the user
Window.alert("check your inputs");
}
#Override
public void onSuccess(String result) {
// TODO Auto-generated method stub
// Add the user to the table.
int row = userFlexTable.getRowCount();
userFlexTable.setText(row, 1, result);
}
});
calNumbers.getUser(new AsyncCallback< ArrayList<User>>() {
public void onFailure(Throwable caught) {
// Show the RPC error message to the user
Window.alert("Problem in database connection");
}
#Override
public void onSuccess( ArrayList<User> result) {
// TODO Auto-generated method stub
}
});
}
}
Here is service implementation
package rpctest.server;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
//import com.hib.HibernateUtil;
import org.hibernate.Session;
import org.hibernate.Transaction;
import hibDomain.User;
import rpctest.client.RpctestService;
public class RpctestServiceImpl extends RemoteServiceServlet implements RpctestService {
public String addUser(String name1, String name2)
throws IllegalArgumentException {
Transaction trns = null;
Session session =
HibernateUtil.getSessionFactory().openSession();
try {
trns = session.beginTransaction();
User user = new User();
user.setFirstName(name1);
user.setLastName(name2);
session.save(user);
session.getTransaction().commit();
} catch (RuntimeException e) {
if(trns != null){
trns.rollback();
}
e.printStackTrace();
} finally{
session.flush();
session.close();
}
return name1+name2; // to test flextable entris only
}
#Override
public ArrayList<User> getUser()
{
List<User> getUser = null;
Transaction trns = null;
Session session =
HibernateUtil.getSessionFactory().openSession();
try {
trns = session.beginTransaction();
getUser = session.createQuery("from User").list();
/* for (Iterator<User> iter = users.iterator(); iter.hasNext();)
{
User user = iter.next();
User[] arrOfObjects = new User[]{user};
} */
trns.commit();
} catch (RuntimeException e) {
if(trns != null){
trns.rollback();
}
e.printStackTrace();
} finally{
session.flush();
session.close();
}
return (ArrayList<User>) getUser;
}
}
The getUser method in service implementation class is showing an error, highlighting method return type i.e. ArrayList But eclipse is giving no suggestion.

Answer 1

Ok. Now, on the client page, create an async call to the service you have created. This link would help you:
http://examples.roughian.com/index.htm#Tutorials~RPC_To_Java
EDIT:
My apologies.
I assume you have serialized the "user" class. If not, you have to serialize it:
class user implements java.io.serializable;
If you want the resultset to convert to the array, do a check if list is null and if result list is not null, convert it to array and assign to user[] like:
try{
....
.... .list();
if(!users.isEmpty(){
getUser = users.toArray();
}
}
and then you can return getUser to the client side.