package test;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.ResultSet;
import com.mysql.jdbc.Statement;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author Administrator
 */
public class DbTest {
    public static void main(String args[])
    {


            try {
                Class.forName("com.mysql.jdbc.Driver");
            } catch (ClassNotFoundException ex) {
                Logger.getLogger(DbTest.class.getName()).log(Level.SEVERE, null, ex);
            }
            Connection conn = null;
            Statement stmt = null;
            ResultSet rs = null;
            try {
                conn = (Connection) DriverManager.getConnection("jdbc:mysql://localhost/test?user=root&pass=1234");            } catch (SQLException ex) {
                Logger.getLogger(DbTest.class.getName()).log(Level.SEVERE, null, ex);
            }
        try {
            stmt = (Statement) conn.createStatement();
            rs = (ResultSet) stmt.executeQuery("SELECT * FROM student");
             while(rs.next())
            {
                System.out.println("姓名："+rs.getString("name")+"---号码:"+rs.getString("number"));
            }
        } catch (SQLException ex) {
            Logger.getLogger(DbTest.class.getName()).log(Level.SEVERE, null, ex);
        }
      
    }
}
//数据库 test 用户名 root 密码 1234 为什么会报这样的信息
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: NO)
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2985)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:885)
        at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:3421)
        at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1247)
        at com.mysql.jdbc.Connection.createNewIO(Connection.java:2748)
        at com.mysql.jdbc.Connection.<init>(Connection.java:1553)
        at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:285)
        at java.sql.DriverManager.getConnection(DriverManager.java:525)
        at java.sql.DriverManager.getConnection(DriverManager.java:193)
        at test.DbTest.main(DbTest.java:34)
Exception in thread "main" java.lang.NullPointerException
        at test.DbTest.main(DbTest.java:39)

看一下你的MySql用的是哪个端口,要把端口号写进语句里