Question

当我向数据库添加内容时，如何显示我的.jsp中的元素。这是我的empservlet或我的代码的servlet

    //empServlet
  package emppackage;
   import java.io.IOException;
   import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;



public class empServlet extends HttpServlet {

String forward;
//empDAO myempDAO;
private static final long serialVersionUID = 1L;
//private empDAO disempdao;

public empServlet() {
    super();

  // myempDAO= new empDAO();
}



protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


}


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    empServices empserv= new empServices();


    empserv.empadd(request.getParameter("eFname"),request.getParameter("eLname"),request.getParameter("eNameRes"),request.getParameter("eSerials"),request.getParameter("eJrss"),request.getParameter("eBand"),request.getParameter("eAcct"),request.getParameter("ePMPs"),request.getParameter("esJRSS"),request.getParameter("eOpenSeatDesc"),request.getParameter("eReqSkills"),request.getParameter("eReqBand"),request.getParameter("eDreject"),request.getParameter("eRreject"),request.getParameter("eDetActPlan"),request.getParameter("eDataComplete"),request.getParameter("eStat"));

    //doGet(request, response);
}

}

这是我的员工dao，它位于arraylist

         //empDAO
     public List<empGetSet> getAllEmp()
 {

List<empGetSet> empdetails = new ArrayList<empGetSet>();

try {

    Connection conn = getConnection();
    String showsql = "SELECT *FROM csemp;";
    PreparedStatement psread= conn.prepareStatement(showsql);
    ResultSet rsread = psread.executeQuery();

    while (rsread.next()) 
    {

        empGetSet readgetset = new empGetSet();

        readgetset.setFname(rsread.getString(1));
        readgetset.setLname(rsread.getString(2));
        readgetset.setNameRes(rsread.getString(3));
        readgetset.setSerials(rsread.getString(4));
        readgetset.setJrss(rsread.getString(5));
        readgetset.setBand(rsread.getString(6));
        readgetset.setAcct(rsread.getString(7));
        readgetset.setPMPs(rsread.getString(8));
        readgetset.setsJRSS(rsread.getString(9));
        readgetset.setOpenSeatDesc(rsread.getString(10));
        readgetset.setReqSkills(rsread.getString(11));
        readgetset.setReqBand(rsread.getString(12));
        readgetset.setDreject(rsread.getString(13));
        readgetset.setsRreject(rsread.getString(14));
        readgetset.setDetActPlan(rsread.getString(15));
        readgetset.setDataComplete(rsread.getString(16));
        readgetset.setStat(rsread.getString(17));


        empdetails.add(readgetset);
        psread.close();
        conn.close();
    }


}

这是我创建的jsp

 <%@ page language="java" 
   contentType="text/html; 
  charset=ISO-8859-1"
  pageEncoding="ISO-8859-1"
   import = "thisPackage.GetSet"
    import = "thisPackage.LoginServlet"
    import = "thisPackage.LogoutServlet"
     %>

   <%
     response.setHeader("Cache-Control", "no-store, no-cache,         must-revalidate");
   response.setHeader("Pragma", "no-cache");

    %>


 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"     "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
   <title>Hi welcome</title>
    </head>
   <body>


<center>

    <h3>Hello </h3> 

</center>

   <form action ="LogoutServlet" method="post">

   <div align="right"><input type = "submit"  value= "Logout"></div>

 </form>

  <table border =1 cellpadding="18">
 <thead>
<tr>
         <th>     First Name</th>
         <th>      Last Name</th>
        <th>      Name of Resource (LN ID Format)</th>
        <th>      Serial Number</th>
        <th>     JRSS</th>
         <th>     Band</th>
         <th>    Account (Proposed)</th>
        <th>    PMP Seat</th>
        <th>    Seat JRSS</th>
        <th>    Open Seat Description</th>
        <th>     Required Skills</th>
        <th>    Required Band low/high</th>
        <th>    Date of Rejection</th>
        <th>Reason for Rejection</th>
        <th>Detailed Action Plan</th>
        <th>Target Date of Completion</th>
        <th>Status(Ongoing/Closed)</th>
        <th colspan=2>Do This</th>

   </tr>
  </thead>


   </table>
  <a href ="addDetails.jsp">Add Details</a>
 </body>
</html>

我怎样才能让它显示出来，我找到了一些资源，但我无法以某种方式将它放入我的项目中，因为它不符合我编写代码的方式。

Answer 1

在servlet中，您可以将request属性设置为DAO查询结果对象。然后循环遍历jsp页面中的数据网格。

Servlet代码＆gt;＆gt;

protected void listEmployees(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    List<empGetSet> empdetails = employeeDAO.getAllEmp(); //or call employeeService layer which calls employeDAO
    request.setAttribute("empdetails", empdetails);
    //dispatcher forward code
}

JSP代码＆gt;＆gt;

<c:forEach var="emp" items="${empdetails}">
    <tr>
        <td><c:out value="${emp.id}" /></td>
        <td><c:out value="${emp.firstName}" /></td>
        <td><c:out value="${emp.lastName}" /></td>
        <!--- etc etc data -->      
    </tr>
</c:forEach>

注意：请更正你的DAO，即将结束PreparedStatement＆amp;结果集读取的while循环内的Connection。把它从rsread.next()的while循环中取出来。如果您使用的是Java 1.7及更高版本，我总是建议使用try with resources，更清洁和更好。更安全的代码。

<强>更新

您有两种JSP操作映射选项：

使用链接

<a href="/list">Show List</a> <!-- this will call doGet() method -->

使用表格

<form action="list" method="post">
        <input type="submit" value="Show List" /> <!-- this will call doPost() method -->
   </form>

servlet端url映射有两个选项：

注释（在Servlet类上）

@WebServlet("/employees") public class EmpServlet extends HttpServlet { /* code */ }
配置（在web.xml中）

<servlet> <servlet-name>EmpServlet</servlet-name> <servlet-class>com.test.EmpServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>EmpServlet</servlet-name> <url-pattern>/employees</url-pattern> </servlet-mapping>

最后你的servlet代码如下所示：

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    doGet(request, response); //if form action chosen
}

// if using doGet() / href option
protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String action = request.getServletPath();

        //you can implement switch case here if having more possible actions/links on the page
        if(action.equals("/list")){
            List<empGetSet> empdetails = employeeDAO.getAllEmp(); //or call employeeService layer which calls employeDAO
            request.setAttribute("empdetails", empdetails);
            RequestDispatcher dispatcher = request.getRequestDispatcher("Employees.jsp");
            dispatcher.forward(request, response);
        }
}

我可以将什么放入myservlet以显示.jsp中的数据库元素

1 个答案: