java jsp显示数据库中的数据

Question

<分区>

Answer 1

您必须从网络浏览器(客户端)请求 doGet servlet 服务方法 - http://localhost:8084/DBConn或 http://localhost:8084/webapp_context/DBConn。

创建一个 POJO，

public class Employee{
   private Integer id;
   private String  name;
   //public constructors and
   //setter/getter
}

并更改您的 servlet 代码，

public class DBConn extends HttpServlet{
  @Override
  public void doGet(HttpServletRequest request, 
                    HttpServletResponse response) 
                       throws IOException, ServletException {
    Connection connection = null;
    Statement stmt=null;
    ResultSet rset=null;
    List<Employee> dataList = new ArrayList<Employee>();
    try {
        // Load the JDBC driver
        String driverName = "oracle.jdbc.driver.OracleDriver";
        Class.forName(driverName);

        // Create a connection to the database
        String serverName = "localhost";
        String portNumber = "1521";
        String sid = "xe";
        String url = "jdbc:oracle:thin:@" + serverName + ":" + portNumber + ":" + sid;
        String username = "hr";
        String password = "hr";
        connection = DriverManager.getConnection(url, username, password);

        stmt = connection.createStatement();
        rset = stmt.executeQuery("select * from employees");
        while (rset.next()) {
            dataList.add(new Employee(rset.getInt("employee_id"),
                                      rset.getString("first_name"));
        }
    } catch (ClassNotFoundException e) {
        // Could not find the database driver
    } catch (SQLException e) {
        // Could not connect to the database
    } finally{
        if(rs!=null){
            try{ 
              rs.close();
            }catch(Exception ex) { /* */ }
        }
        if(stmt!=null){
            try{ 
              stmt.close();
            }catch(Exception ex) { /* */ }
        }
        if(connection !=null){
            try{ 
              connection.close();
            }catch(Exception ex) { /* */ }
        }
     }

     request.setAttribute("data", dataList);
     String strViewPage = "index.jsp";
     RequestDispatcher dispatcher = request.getRequestDispatcher(strViewPage);
      if (dispatcher != null) {
         dispatcher.forward(request, response);
      }
   }
}

和 index.jsp 中的标记，

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:forEach var="employee" items="${data}">
  <br/> ${employee.id}  ${employee.name}
</c:forEach>

注意:切勿在默认包 中创建类型(类)。您必须必须指定 POJO 和 Servlet 子类的包名称。