求大神帮忙，JAVAEE和数据库的问题

package getservlets;import java.io.IOException;
import java.io.PrintWriter;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;
import java.sql.SQLException;import java.sql.Statement;import javax.servlet.*;
import javax.servlet.http.*;public class GetServlets extends HttpServlet {
    private static final String CONTENT_TYPE = "text/html; charset=GBK";
      
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }
      public void service(HttpServletRequest request,
                        HttpServletResponse response) throws ServletException,
                                                             IOException {
        response.setContentType(CONTENT_TYPE);
        PrintWriter out = response.getWriter();
       
        out.println("<html>");
        out.println("<head><title>GetServlets</title></head>");
        out.println("<body>");
        Connection conn=null;
        Statement stmt=null;
        ResultSet rs=null; 
        //1.装载驱动
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
        } catch (ClassNotFoundException e) {
            //System.out.println("driver not found");
        }
        //2.创建连接.        try {
            conn=DriverManager.getConnection("jdbc:oracle:thin@localhost:1521:ORCL","scott","woshihk");
        } catch (SQLException e) {     
        }        //3.创建发送SQL语句的对象：Statement.        try {
            stmt=conn.createStatement();
        } catch (SQLException e) {
        }
        //4.进行数据库操作:
        
        try {
            rs = stmt.executeQuery("SELECT*FROM dept");
        } catch (SQLException e) {
        }
        //5.处理操作结果
        try {
            while(rs.next()){
            out.println(rs.getInt(1)+"       "+ rs.getString(2)+ "       " +rs.getString(3)+"<br>");
                }
        } catch (Exception e) {
                  e.printStackTrace();
              } finally {
                  try {
                      if (rs != null)
                          rs.close();
                      if (stmt != null)
                          stmt.close();
                      if (conn != null)
                          conn.close();
                  } catch (SQLException sqle) {
                      // TODO: Add catch code
                      sqle.printStackTrace();
                  }              }
       /*} catch (SQLException e) {
            }finally{
            try{if(rs!=null)
                    rs.close;
                if(stmt!=null)
                    stmt.close;
                if(conn!=null)
                    conn.close;
                }catch(Exception e)
            e.printStackTrace();}*/
        out.println("<p>The servlet has received a POST or GET. This is the reply.</p>");
        out.println("</body></html>");
        out.close();
    }    
}为什么报空指针错误啊？
我只是想查询数据库里的内容
Q307540690，若有大神帮助小的感激不尽，我是初学者