Question

drivermanager.getconnection 返回null

public class DBcon {

private static Connection conn = null ;

public static Connection getConnection() {

if(conn==null){
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
} catch (Exception e) {

e.printStackTrace();
}
String url = "jdbc:mysql://localhost:3306/norice_farm";
String username = "root";
String password = "root";
try {
Connection con = DriverManager.getConnection(url, username, password);
} catch (Exception e) {
e.printStackTrace();
}
}
return conn;
}
}

Answer 1

你的赋值语句错了

Connection con = DriverManager.getConnection(url, username, password);

但返回的对象却是conn;

Answer 2

try {
conn = DriverManager.getConnection(url, username, password);
} catch (Exception e) {
e.printStackTrace();
}

Answer 3

可能数据库密码错误