Struts2 防止表单重复提交笔记

作者：简简单单 2014-06-17

下面我们来看一个例子

代码如下

复制代码

public class HelloServlet extends HttpServlet {
private int i = 0;

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
   throws ServletException, IOException {
  String userName = req.getParameter("name");
  String password = req.getParameter("password");
  int count = 0;
  for (int i = 0; i < 1000; i++) {
   count++;
  }

  resp.getWriter().println(
    i + ": hello" + userName + " your password is " + password);
  i++;
}
}

input.jsp

测试（提交后刷新页面）：

我们看到，在提交之后，刷新页面，同样会触发服务端的操作！

session方式防止重复提交

代码如下

复制代码

InputServlet.java

public class InputServlet extends HttpServlet {

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
   throws ServletException, IOException {

  String token = String.valueOf(System.currentTimeMillis());
  req.setAttribute("token",token);
  req.getSession().setAttribute("token",token);

  RequestDispatcher rd = req.getRequestDispatcher("/input.jsp");
  rd.forward(req,resp);
}
}

HelloServlet.java

public class HelloServlet extends HttpServlet {

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {

String reqToken = req.getParameter("token");
String sessionToken = (String) req.getSession().getAttribute("token");

if (reqToken == null || !reqToken.equals(sessionToken)) {

   resp.getWriter().println("repeat submit");
   return;
  }

  //删除session中的token
  req.getSession().removeAttribute("token");

  String userName = req.getParameter("name");
  String password = req.getParameter("password");
  int count = 0;
  for (int i = 0; i < 1000; i++) {
   count++;
  }

resp.getWriter().println(
": hello" + userName + " your password is " + password);
}
}
input.jsp