java.sql.SQLException:对用户'root'@'localhost'拒绝访问(使用密码:YES)

Question

为什么你认为这个函数总是让我？使用另一个具有相同代码结构的登录程序,它可以很好地工作.我的DBURL是jdbc:mysql:// localhost:8889/database

    public String retrieveUserPassword(String userName, String password) {

    String query = "SELECT UserPassword FROM Access where UserName='"+userName+"'";
    String dbresult=null; //this might be the problem, but I must define it

    try {
      Class.forName("com.mysql.jdbc.Driver");

    }catch (ClassNotFoundException ex1) {

      System.out.println("Driver could not be loaded: " + ex1);
      Logger.getLogger(DatabaseModel.class.getName()).log(Level.SEVERE, null, ex1);
    }
    try {

          //These are private variables declared at the top of the class 
          //and used by various functions   
          con = DriverManager.getConnection(DatabaseURL, userName, password);   
          st = con.createStatement(); 
          rs = st.executeQuery(query);

            if(rs.next()){

                dbresult= rs.getString(3);
            }

     }catch (SQLException e) {

      e.printStackTrace();
     }    

  return dbresult;

}

Access表由三列组成:UserID,UserName,UserPassword

Answer 1

java.sql.SQLException:对用户'root'@'localhost'拒绝访问(使用密码:YES)

正如您所提到的,问题在于与数据库本身建立连接.声明

con = DriverManager.getConnection(DatabaseURL, userName, password);

正在抛出被抓住的异常

catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   

之后您将返回dbresult已初始化的null(您必须将其作为局部变量).所以问题是由于身份验证,您无法连接到数据库.

在您的计算机上(在本例中为localhost)从控制台运行以下命令

GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY 'root' WITH GRANT OPTION;