java to mysql connection errorconn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/DB, "root", "password"); error message: Exception in thread "main" java.sql.SQLException: Data source rejected establishment of connection, message from server: "Host 'idwsg' is not allowed to connect to this MySQL server" at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:589) at com.mysql.jdbc.Connection.createNewIO(Connection.java:1654) at com.mysql.jdbc.Connection.(Connection.java:432) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:400) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at Simexecute.connectDB(Simexecute.java:3432) at Simexecute.(Simexecute.java:310) at Simexecute.main(Simexecute.java:3461) 请问这个问题出在server, j2-re, java-connector, 还是 mysql-server 的configuration ?