useraccountbean.java

J2EE技术是一种可以信赖的企业级软件开发技术

package useraccount;

import javax.ejb.SessionBean;
import javax.ejb.SessionContext;
import javax.ejb.CreateException;
import java.sql.Connection;
import java.sql.*;
import javax.sql.*;
import javax.naming.*;

public class UserAccountBean implements SessionBean {
    SessionContext sessionContext;
    String id=null;
    String password=null;
    Connection conn=null;

    public void ejbCreate(String id, String password) throws CreateException,SQLException,NamingException {
      InitialContext ctx=new InitialContext();
      DataSource ds=(DataSource)ctx.lookup("test");
      conn=ds.getConnection();
      PreparedStatement pstmt=conn.prepareStatement("Select password from account where id=?");
      pstmt.setString(1,id);
      ResultSet rs=pstmt.executeQuery();
      if(rs.next()){
      String pw=rs.getString("password");
      if(password.equals(pw)){
          this.id=id;
          this.password=password;
          return;
      }else{
          conn.close();
          conn=null;
          throw new CreateException("Incorrect User Id!");
      }
      }

    }

    public void ejbRemove() {
        try{
                        id=null;
                        password=null;
                        conn.close();
                        conn=null;
                }
                catch(Exception ex){
                        ex.printStackTrace();
                }

    }

    public void ejbActivate() {
        try{
                        InitialContext ctx=new InitialContext();
                        DataSource ds=(DataSource)ctx.lookup("test");
                        conn=ds.getConnection();
                }
                catch(Exception ex){
                        ex.printStackTrace();
                }

    }

    public void ejbPassivate() {
        try{
                        conn.close();
                        conn=null;
                }
                catch(Exception ex){
                        ex.printStackTrace();
                }

    }


    public void setSessionContext(SessionContext sessionContext) {
        this.sessionContext = sessionContext;
    }

    public double  Balance()throws SQLException {
        PreparedStatement pstmt=null;
                pstmt=conn.prepareStatement("SELECT balance FROM account WHERE id=?");
                pstmt.setString(1,id);
                ResultSet rs=pstmt.executeQuery();
                if(rs.next()){
                        double balance=rs.getDouble("balance");
                        pstmt.close();
                        return balance;
                }
                else{
                        pstmt.close();
                        throw new SQLException("None user id can be found!");
                }

    }

    public void Withdraw(double amount)throws SQLException {
        PreparedStatement pstmt=null;
                pstmt=conn.prepareStatement
               ("UPDATE account SET balance=balance-? WHERE id=?");
                pstmt.setDouble(1,amount);
                pstmt.setString(2,id);
                if(pstmt.executeUpdate()==1){
                        pstmt.close();
                        return;
                }
                else{
                        pstmt.close();
                        throw new SQLException("Can't update the database!");
                }

    }

    public void Deposit(double amount)throws SQLException {
        PreparedStatement pstmt=null;
                pstmt=conn.prepareStatement("UPDATE account SET balance=balance+? WHERE id=?");
                pstmt.setDouble(1,amount);
                pstmt.setString(2,id);
                if(pstmt.executeUpdate()==1){
                        pstmt.close();
                        return;
                }
                else{
                        pstmt.close();
                        throw new SQLException("Can't update the database!(deposit)");
                }

    }

    public void Transfer(String toId, double amount)throws SQLException {
        PreparedStatement pstmt=null;
                pstmt=conn.prepareStatement("UPDATE account SET balance=balance-? WHERE id=?");
                pstmt.setDouble(1,amount);
                pstmt.setString(2,id);
                if(pstmt.executeUpdate()==1){
                        pstmt.close();
                }
                else{
                        pstmt.close();
                        throw new SQLException("Can't update the database!");
                }

                pstmt=conn.prepareStatement("UPDATE account SET balance=balance+? WHERE id=?");
                pstmt.setDouble(1,amount);
                pstmt.setString(2,toId);
                if(pstmt.executeUpdate()==1){
                        pstmt.close();
                        return;
                }
                else{
                        pstmt.close();
                        throw new SQLException("Can't update the database!(deposit)");
                }

    }
}