package news;
import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;
public class DBConn{
  private Connection conn;
  public DBConn()
   {
     try{
     //加載驅動程序
     Context initCtx = new InitialContext();
     Context ctx = (Context) initCtx.lookup("java:comp/env");
     //獲取連接池對象
     DataSource ds =(DataSource)ctx.lookup("jdbc/news");
     //創建連接
     conn = ds.getConnection();
    }
    catch(Exception e)
    {
      System.out.print(e.toString());
    }
  }
  public synchronized Statement getStmt()throws Exception
   {
     Statement stmt;
     stmt=conn.createStatement();
     return stmt;
   }
  //創建預處理會話對象
  public synchronized PreparedStatement getPstmt(String sql)throws Exception
   {
     PreparedStatement pstmt;
     pstmt=conn.prepareStatement(sql);
     return pstmt;
   }
  //執行查詢操作
  public synchronized ResultSet query(String sql)throws Exception
 {
  try{
    Statement stmt;
    stmt=conn.createStatement();
    ResultSet rs=stmt.executeQuery(sql);
    return rs;
   }
  catch(Exception e)
  {
   System.out.println(e.toString());
   return null;
  }
 }
 //執行更新操作
public synchronized int update(String sql)throws Exception
 {
   int nn;
   try{
   Statement stmt;
   stmt=conn.createStatement();
   nn=stmt.executeUpdate(sql);
  }
  catch(Exception e)
  {
   System.out.println(e.toString());
   nn=0;
  }
  return nn;
 }
 public void DBclose() throws SQLException {
   if(conn!=null){
     conn.close();
     conn=null;
   }
 }
}