java - 用户 'root' @'localhost' 的访问被拒绝(使用密码 : NO) when ToGet url have db parameter

Question

我搜索了论坛，但没有任何东西可以帮助我解决我的问题。我需要通过 doGet mether 从 URL 获取数据库参数“db”我认为发生这种情况是因为程序不会从 ULR 读取我的密码(是的，传递到 URL 是个坏主意，但这正是本练习所需要的。

每次发生这种情况时:

Access denied for user 'root'@'localhost' (using password: NO) 

当我尝试使用以下网址启动我的服务时，会出现此问题:

http://localhost:8080/Pl/?db=jdbc:mysql://localhost:3307/baza?user=root&password=krasnal

有人知道这是问题所在吗？也许 jdbc:mysql://localhost:3307/baza?user=root&password=krasnal 出了问题？我检查了一下，这是一个好的密码。

这是我的错误页面:

HTTP Status 500 - 

--------------------------------------------------------------------------------

type Exception report

message 

description The server encountered an internal error that prevented it from fulfilling this request.

exception 

java.lang.NullPointerException
    Plain.getLargestRegionArea(Pl.java:303)
    Pl.baza(Pl.java:113)
    Pl.doGet(Pl.java:101)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


note The full stack trace of the root cause is available in the Apache Tomcat/7.0.56 logs.

我不需要打开它在命令提示符中打开，只需要它在 Eclipse 中工作即可。我的代码还有一些:

public class Pl extends HttpServlet {
    private static final long serialVersionUID = 1L;


    private static final String QUERY = "SELECT x, y, z FROM baza";

    /**
     * Method connecting to database and gets the data needed to perform the
     * Plain algorithm
     * 
     * @param connector
     * @return The Map with coordinates in 2D space with key which is result of
     *         function z = f(x,y).
     */
    public static Map<Float, List<Point2D.Float>> dbconnection(
            final String connector) {

        Map<Float, List<Point2D.Float>> coordinates = null;

        try {
          Class.forName("com.mysql.jdbc.Driver");
        }
        catch (ClassNotFoundException e) {
          // driver not found
        }

        try {

            Connection conn = DriverManager.getConnection(connector);
            Statement statement = conn.createStatement();

            coordinates = retriveData(statement.executeQuery(QUERY));

            statement.close();
            conn.close();

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return coordinates;
    }

    /**
     * Main method. Executing and solving the problem. Should have only one
     * parameter: -connection_string .
     * 
     * @param args
     *            connection_string
     * @return 
     */

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        String parametr = request.getParameter("db"); // pobranie parametru z
                                                        // adresu url

        String k="jdbc:mysql://localhost/baza?user=root&password=krasnal";
        String w=parametr;
        Locale fmtLocale = Locale.getDefault(Category.FORMAT);
        NumberFormat formatter = NumberFormat.getInstance(fmtLocale);
        formatter.setMaximumFractionDigits(5);
        formatter.setMinimumFractionDigits(5);


        response.getWriter().write("Wynik to:  "+formatter.format(baza(w))+parametr);
        //response.getWriter().write(int.format(Locale.US, "Koszt : %.3f",  wynik));
    }




    public static double baza(String k){
        //String par ="jdbc:mysql://localhost/baza?user=root&password=krasnal";
      //  if (args.length == 1) {
            Map<Float, List<Point2D.Float>> coordinates = dbconnection(k);
            Plain plain = new Plain(coordinates);
            double wynik=plain.getLargestRegionArea();
           System.out.format(String.format(Locale.US, "Koszt : %.3f",  wynik));

            return wynik;
    }

    /**
     * This method gets data from {@link ResultSet} to list contains points in
     * 2D space and result of function z = f(x,y).
     * 
     * @param result
     *            The set with fetch data
     * @return The HasjMap with coordinates in 2D space with key which is result
     *         of function z = f(x,y).
     * @throws SQLException
     */


    private static Map<Float, List<Point2D.Float>> retriveData(
            final ResultSet result) throws SQLException {
        Map<Float, List<Point2D.Float>> coordinates = new HashMap<Float, List<Point2D.Float>>();

        while (result.next()) {
            Point2D.Float point = new Point2D.Float(result.getFloat("x"),
                    result.getFloat("y"));

            if (coordinates.containsKey(result.getFloat("z"))) {
                coordinates.get(result.getFloat("z")).add(point);
            } else {
                List<Point2D.Float> points = new LinkedList<Point2D.Float>();
                points.add(point);
                coordinates.put(result.getFloat("z"), points);

            }
        }

        return coordinates;
    }
}

Answer 1

http://localhost:8080/Pl/?db=jdbc:mysql://localhost:3307/baza?user=root&password=krasnal

password 参数被解释为 servlet 的第二个参数，而不是 db 参数的一部分。本质上，您的 servlet 接收的参数是:

 db       - jdbc:mysql://localhost:3307/baza?user=root
 password - krasnal

将数据库密码作为 URL 参数发送到 servlet 是一个极其糟糕的主意。 不要这样做。

话虽这么说，转义 db 参数内容的 URL 可能会导致其被正确解析，例如

?db=jdbc%3Amysql%3A//localhost%3A3307/baza%3Fuser%3Droot%26password%3Dpleasehackme

我对 Java 有点生疏，所以我不确定这是否能“按原样”工作。您可能需要对 servlet 中的参数进行转义才能使用它。