java.sql.SQLException：拒绝用户“root”@“localhost”的访问（使用密码：YES）
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java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
提问by QGA
Why do you think this function gives me always null?? Using another login program, which has the same code structure, it works greatly. My DBURL is jdbc:mysql://localhost:8889/database
为什么你认为这个函数给我总是空？使用另一个具有相同代码结构的登录程序，效果很好。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;
}
The Access table is composed of three columns: UserID, UserName, UserPassword
Access表由三列组成：UserID、UserName、UserPassword
采纳答案by Aniket Thakur
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
java.sql.SQLException：拒绝用户“root”@“localhost”的访问（使用密码：YES）
As you have mentioned problem is with creating connection with the database itself. Statement
正如您所提到的，问题在于与数据库本身建立连接。陈述
con = DriverManager.getConnection(DatabaseURL, userName, password);
is throwing exception which is getting caught at
正在抛出被捕获的异常
catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
after which you are returning dbresultwhich you have initialized to null(which you have to as it is a local variable). So the problem is that you are unable to connect to your db due to authentication.
之后，您将返回dbresult已初始化的null（您必须这样做，因为它是一个局部变量）。所以问题是由于身份验证，您无法连接到您的数据库。
On your machine where (localhost in ur case ) run the following command from console
在您的机器上（在您的情况下为 localhost ）从控制台运行以下命令
GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY 'root' WITH GRANT OPTION;
