想利用List实现向数据库中插入一堆数据,但是创建List对象时出错。
List list = (List)session.getAttribute("listname");
if(list==null)
List list = new ArrayList(); //???The left-hand side of an assignment must be a variable?
list.add(one);
session.setAttribute("listname", list);
完整代码
package servlet;
import java.io.IOException;
import java.util.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import beans.St;
/**
* Servlet implementation class Insert_2
*/
@WebServlet("/insert_2")
public class Insert_2 extends HttpServlet {
private static final long serialVersionUID = 1L;
private ServletRequest session;
/**
* @see HttpServlet#HttpServlet()
*/
public Insert_2() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
String xh = request.getParameter("xh");
String xm = request.getParameter("xm");
double cj = Double.parseDouble(request.getParameter("cj"));
String xz = request.getParameter("xz");
St one = new St(xh, xm, cj);
List list = (List)session.getAttribute("listname");
if(list==null)
List<St> list = new ArrayList<St>(); //???
list.add(one);
session.setAttribute("listname", list);
if(!xz.equals("no")) {
request.setAttribute("aaa", list);
RequestDispatcher rd = request.getRequestDispatcher("insert_22");
rd.forward(request, response);
System.out.println(xz+"结束");
}
else {
RequestDispatcher rd = request.getRequestDispatcher("input_insert1.jsp");
rd.forward(request, response);
System.out.println(xz+"继续");
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}