Question

我的Spring MVC应用程序中有以下文件： login.jsp ， HomeController.java 和 DatabaseService.java 。当有人点击 login.jsp 中的登录按钮时，它会将数据（用户名和密码）传输到 HomeController.java ，然后 HomeController.java 调用 DatabaseService.java ，带有一些条件并从中获取响应，最后将响应返回到 login.jsp 。到目前为止，无效的用户名和密码字段都可以。当 login.jsp 中的用户名和密码与存储的用户名和密码匹配时，会出现问题。问题是，没有数据存储到会话变量/对象中。我尝试了几种方法：

public String dblogin(String username, String password) throws SQLException {
    String response = "";
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs;
    String pass = "", fname = "", lname = "";
    int userid = 0;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bloodspring", "root", "");
        stmt = conn.createStatement();
        try {
            String query = "SELECT user_id, user_fname, user_lname, pword FROM bld_user WHERE uname='"+ username +"'";
            rs = stmt.executeQuery(query);
            int res = 0;
            while( rs.next() ) {
                res++;
                pass = rs.getString("pword");
                fname = rs.getString("user_fname");
                lname = rs.getString("user_lname");
                userid = rs.getInt("user_id");
            }
            if( res == 0 ) {
                response = "Invalid Username";
            } else {
                //String new_pass = crypt.encryption(password);
                if( crypt.encryption(password).compareTo(pass) != 0 ) {
                    response = "Invalid username and/or password";
                    //response = "Original :" + pass + " :::: new : " + crypt.encryption(password);
                } else {
                    HttpServletRequest request;
                    HttpSession session = request.getSession();
                    session.setAttribute("fname", fname);
                    session.setAttribute("lname", lname);
                    session.setAttribute("username", username);
                    session.setAttribute("userid", userid);
                    response = "Login Successful";
                }
            }
        } catch( SQLException Ex) {
            Ex.printStackTrace();
            response = "Sorry something goes wrong with your MySQL query or server";
        }
    } catch( ClassNotFoundException E) {
        E.printStackTrace();
        response = "Sorry no MySQL class found";
    }
    return response;
}

但它显示了一些空指针异常相关错误。显示我更改代码如下：

public String dblogin(String username, String password) throws SQLException {
    String response = "";
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs;
    String pass = "", fname = "", lname = "";
    int userid = 0;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bloodspring", "root", "");
        stmt = conn.createStatement();
        try {
            String query = "SELECT user_id, user_fname, user_lname, pword FROM bld_user WHERE uname='"+ username +"'";
            rs = stmt.executeQuery(query);
            int res = 0;
            while( rs.next() ) {
                res++;
                pass = rs.getString("pword");
                fname = rs.getString("user_fname");
                lname = rs.getString("user_lname");
                userid = rs.getInt("user_id");
            }
            if( res == 0 ) {
                response = "Invalid Username";
            } else {
                //String new_pass = crypt.encryption(password);
                if( crypt.encryption(password).compareTo(pass) != 0 ) {
                    response = "Invalid username and/or password";
                    //response = "Original :" + pass + " :::: new : " + crypt.encryption(password);
                } else {
                    HttpServletRequest request = null;
                    try {
                        HttpSession session = request.getSession();
                        session.setAttribute("fname", fname);
                        session.setAttribute("lname", lname);
                        session.setAttribute("username", username);
                        session.setAttribute("userid", userid);
                        response = "Login Successful";
                        //response = fname + " " + lname;
                    } catch( java.lang.NullPointerException lex ) {
                        lex.printStackTrace();
                        response = "Something Wrong";
                    }
                }
            }
        } catch( SQLException Ex) {
            Ex.printStackTrace();
            response = "Sorry something goes wrong with your MySQL query or server";
        }
    } catch( ClassNotFoundException E) {
        E.printStackTrace();
        response = "Sorry no MySQL class found";
    }
    return response;
}

但它返回响应为“Something Wrong”[抓住java.lang.NullPointerException的块]。如果我按如下方式更改代码：

public String dblogin(String username, String password) throws SQLException {
    String response = "";
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs;
    String pass = "", fname = "", lname = "";
    int userid = 0;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bloodspring", "root", "");
        stmt = conn.createStatement();
        try {
            String query = "SELECT user_id, user_fname, user_lname, pword FROM bld_user WHERE uname='"+ username +"'";
            rs = stmt.executeQuery(query);
            int res = 0;
            while( rs.next() ) {
                res++;
                pass = rs.getString("pword");
                fname = rs.getString("user_fname");
                lname = rs.getString("user_lname");
                userid = rs.getInt("user_id");
            }
            if( res == 0 ) {
                response = "Invalid Username";
            } else {
                //String new_pass = crypt.encryption(password);
                if( crypt.encryption(password).compareTo(pass) != 0 ) {
                    response = "Invalid username and/or password";
                    //response = "Original :" + pass + " :::: new : " + crypt.encryption(password);
                } else {
                    HttpServletRequest request = null;
                    try {
                        response = fname + " " + lname;
                    } catch( java.lang.NullPointerException lex ) {
                        lex.printStackTrace();
                        response = "Something Wrong";
                    }
                }
            }
        } catch( SQLException Ex) {
            Ex.printStackTrace();
            response = "Sorry something goes wrong with your MySQL query or server";
        }
    } catch( ClassNotFoundException E) {
        E.printStackTrace();
        response = "Sorry no MySQL class found";
    }
    return response;
}

比它正常工作并从数据库返回名字，姓氏。所以我认为我的代码不适合会话谁能告诉我如何将数据库中的数据存储到会话中。

Answer 1

您可以使用spring-security进行身份验证。除此之外，您可以按照以下代码段进行操作。请注意，您并不需要在会话中单独存储所有字段。您只需将用户对象存储到会话中即可。

@RequestMapping(value = "login.html", method = RequestMethod.POST)
            public ModelAndView post(@ModelAttribute("login") LoginEntity login, HttpServletRequest req) {


    /*    CHECK IN DATABASE if the user name and password matches or not */
    UserObject userObject=dblogin(login.userName,login.password);


    if(userObject!=null){
        HttpSession session = req.getSession(true);
        session.setAttribute("user",userObject);
    }
    else
       return new ModelAndView("login");
    }

如何初始化会话并在JSP中正确使用它们？

1 个答案: