Question

我尝试在MVC模式下创建一个Web应用程序来显示来自DB的数据

JSP：

<c:forEach var="pro" items="${list}">
            <tr>
           <td><c:out value="${pro.reqno}"></c:out></td>
           <td><c:out value="${pro.leave_Type}"></c:out></td>
           <td><c:out value="${pro.no_of_days}"></c:out></td>
           <td><c:out value="${pro.status}"></c:out></td>
           <td><c:out value="${pro.balanceUnits}"></c:out></td>
           <td><c:out value="${pro.totalUnits}"></c:out></td>
            </tr>
    </c:forEach>

的Servlet

           ArrayList temp = summary.getSummary(objUsr);
           request.setAttribute("list", temp);
           RequestDispatcher rd = request.getRequestDispatcher("JSP/login-success.jsp");

DAO课程：

public ArrayList<LeaveSummary> getSummary(LeaveSummary objUsr) throws SQLException {
    PreparedStatement stmt = null;
    ArrayList<LeaveSummary> rowArray = new ArrayList<LeaveSummary>();
    ResultSet rs = null;
    try {
        LeaveSummary getValuesFromDb = new LeaveSummary();
        Connection con = ConnectionProvider.getCon();
        stmt = con.prepareStatement("SELECT * FROM create_request where username=?");
        stmt.setString(1, objUsr.getUser_name());
        rs = stmt.executeQuery();
        while (rs.next()) {
            getValuesFromDb.setReqno(rs.getInt(1));
            getValuesFromDb.setUser_name(rs.getString(2));
            getValuesFromDb.setNo_of_days(rs.getInt(4));
            getValuesFromDb.setLeave_Type(rs.getString(3));
            getValuesFromDb.setStatus(rs.getString(6));
            getValuesFromDb.setTotalUnits(rs.getInt(7));
            getValuesFromDb.setBalanceUnits(rs.getInt(8));
            rowArray.add(getValuesFromDb);
        }
    }
   catch(Exception e)
           {
       e.printStackTrace();
   }

数据库表：

1 san                  Casual                        1 sicks                pending                                                  10                                      9 
2 san                  Others                        2 Functional           pending                                                  10                                      8

但它仅打印第二行（即）最近添加的行，如何从表中打印两行

Answer 1

创建新实例

LeaveSummary getValuesFromDb = new LeaveSummary();

在你的while循环中

。您没有为数据库中的每个记录创建一个新的LeaveSummary实例。因此，每次循环结果集时都会重写相同的对象。这就是为什么单独的最后一条记录存在于列表中。

Answer 2

问题是你要修改同一个对象并将其添加到列表中。在循环中创建新对象。

  LeaveSummary getValuesFromDb = new LeaveSummary();
    Connection con = ConnectionProvider.getCon();
    stmt = con.prepareStatement("SELECT * FROM create_request where username=?");
    stmt.setString(1, objUsr.getUser_name());
    rs = stmt.executeQuery();
    while (rs.next()) {
        //Add this line   
        getValuesFromDb = new LeaveSummary();
        getValuesFromDb.setReqno(rs.getInt(1));
        getValuesFromDb.setUser_name(rs.getString(2));
        getValuesFromDb.setNo_of_days(rs.getInt(4));
        getValuesFromDb.setLeave_Type(rs.getString(3));
        getValuesFromDb.setStatus(rs.getString(6));
        getValuesFromDb.setTotalUnits(rs.getInt(7));
        getValuesFromDb.setBalanceUnits(rs.getInt(8));
        rowArray.add(getValuesFromDb);
    }

Answer 3

试试此代码

LeaveSummary getValuesFromDb = new LeaveSummary();
    Connection con = ConnectionProvider.getCon();
    stmt = con.prepareStatement("SELECT * FROM create_request where username=?");
    stmt.setString(1, objUsr.getUser_name());
    rs = stmt.executeQuery();
    while (rs.next()) {

        getValuesFromDb = new LeaveSummary();
        getValuesFromDb.setReqno(rs.getInt(1));
        getValuesFromDb.setUser_name(rs.getString(2));
        getValuesFromDb.setNo_of_days(rs.getInt(4));
        getValuesFromDb.setLeave_Type(rs.getString(3));
        getValuesFromDb.setStatus(rs.getString(6));
        getValuesFromDb.setTotalUnits(rs.getInt(7));
        getValuesFromDb.setBalanceUnits(rs.getInt(8));
        rowArray.add(getValuesFromDb);
    }

ArrayList迭代相同的数据

3 个答案: