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[Java][Servlet] Cannot call sendRedirect() after the response has been committed

做一个Login Demo的时候,写了如下代码:


protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    super.doPost(request, response);
    
    String userName = request.getParameter("userName");
    String password = request.getParameter("password");

    if (userName.equals("test")) {
        response.sendRedirect(request.getContextPath() + "/success/success.jsp");
    } else {
        response.sendRedirect(request.getContextPath() + "/error/login-failed.jsp");
    }
}

运行程序时报错了Cannot call sendRedirect() after the response has been committed,意思已经很明确了,就是说不能在一个response做了提交之后再重定向,也就是说再重定向之前不要去改变response,包括如下部分:

  • 修改response中参数的值,cookie,session 等
  • 重定向

请注意在做doPost(..)的时候我这里调用了super.doPost(..),而super.doPost(..)做了什么呢?

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

    String protocol = req.getProtocol();
    String msg = lStrings.getString("http.method_post_not_supported");
    if (protocol.endsWith("1.1")) {
        resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
    } else {
        resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
    }
}

response被修改了,我们注释掉super.doPost(..),程序正常运行。

posted @ 2016-10-29 14:09  种花生的读书人  阅读(29998)  评论(0编辑  收藏  举报

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