Question

我正在尝试使用Ajax，Servlet和HTML从我的数据库中删除用户。当我提交数据时发生非法调用。我认为连接或SQL语句没有任何问题

delete.html

<input type="text" id="delete">
<input type="submit" onclick="deleteUSer()" value="Delete">

delete.js

function deleteUSer(){

        var username = document.getElementById("delete");

        var params = {

            username: username
        }

    $.post("Delete", params, function(data){}
            )

}

Delete.java servlet

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = null;
        DBUtils dbutils = null;
        Connection conn = null;
        try{

            String username = request.getParameter("username");

            dbutils = new DerbyUtils();
            conn = dbutils.getConnection();

            DeleteDAO dao = new DeleteDAO(conn);

            dao.deleteUser(username);



            RequestDispatcher dispatcher =
            getServletContext().getRequestDispatcher("/index.html");
            dispatcher.forward(request, response);



        }

DeleteDAO.java

public void deleteUser(String username) throws SQLException{
      try{


          String sql = "delete from users where username='"+username+"'";

          PreparedStatement ps = this.conn.prepareStatement(sql);

          ps.executeQuery();

Answer 1

您发送的是html doc elemect而非用户名...

试试这个 -

<input type="text" id="delete" value="vivek">
<input type="submit" onclick="deleteUSer()" value="Delete">


    function deleteUSer(){

            var username = document.getElementById("delete");

            var params = {

                username: username.value
            }

        $.post("Delete", params, function(data){}
                )

    }

Answer 2

如果你正试图制定＆＃34;删除＆＃34;您可以使用HTTP请求的命令，您想要使用$.ajax，而不是$.post。

引用文档（https://api.jquery.com/jQuery.post/）：

这是一个简写的Ajax函数，相当于：

$.ajax({
  type: "POST",
  url: url,
  data: data,
  success: success,
  dataType: dataType
});

如果你正试图制定＆＃34;删除＆＃34;，你想做的事情如下：

var dataObj = {
        'username': document.getElementById("delete").value;
    }
$.ajax({
    type:"DELETE",
    data: dataObj,
    url: 'url/to/your/servlet'
});

你可能还想在其中包含一个数据类型，但是对于这个例子，jquery可以解决它。

未捕获的TypeError：非法调用

2 个答案: