Exception in thread "main" java.sql.SQLException: Access denied for user 'root'@'localhost' (using p

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;  
import java.sql.DriverManager;  
import java.sql.PreparedStatement;
import java.sql.ResultSet;  
import java.sql.SQLException;  
import java.sql.Statement;  
import java.util.Properties;
  


          
        public class BasicConnectionDemo  
        {  
          
            /** 
             * @param args 
             */  
            public static void main(String[] args)throws Exception  
            {  
            String driver;
            String url ;  
                String username ;  
                String password ;  
                String sql = "select * from kk";  
               
                InputStream in = BasicConnectionDemo.class.getClassLoader().getResourceAsStream("db.properties");  
                Properties pro = new Properties();  
                try {  
                    pro.load(in);  
                } catch (IOException e) {  
                     
                    e.printStackTrace();  
                } 
                driver = pro.getProperty("driver");  
                url = pro.getProperty("url");  
                username = "root";  
                password = "111111";
                
                System.out.println(password);
                easyConnect(url, username, password, sql);  
            }  
            public static void easyConnect(String url,String user,String password,String sql)  
                    throws ClassNotFoundException, SQLException  
            {  
            try{
                   Class<?> aa= Class.forName("com.mysql.jdbc.Driver"); 
                   System.out.println(aa);
                    }
                    catch (ClassNotFoundException e) {  
                       
                        e.printStackTrace();
                    }
                Connection conn = DriverManager.getConnection(url,user,password);  
                Statement stat = conn.createStatement();  
                ResultSet rs = stat.executeQuery(sql);  
                while(rs.next())  
                {  
                    System.out.print(rs.getObject("id") + " ");  
                    System.out.print(rs.getObject("name") + " ");  
                    System.out.print(rs.getObject("age") + "\n");  
                }  
                rs.close();  
                stat.close();  
                conn.close();  
            }  

        }

改为   password = "727272";为
                  password=pro.getProperty("password"); 
后异常，Exception in thread "main" java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4417)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1278)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at BasicConnectionDemo.easyConnect(BasicConnectionDemo.java:58)
at BasicConnectionDemo.main(BasicConnectionDemo.java:42)

把Class.forName("com.mysql.jdbc.Driver");
改为Class.forName( driver);

Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver  
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at BasicConnectionDemo.easyConnect(BasicConnectionDemo.java:48)
at BasicConnectionDemo.main(BasicConnectionDemo.java:42)

把username="root";
改为 username = pro.getProperty("username ");
异常:
Exception in thread "main" java.sql.SQLException: Access denied for user ''@'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4417)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1278)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2284)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2083)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at BasicConnectionDemo.easyConnect(BasicConnectionDemo.java:58)
at BasicConnectionDemo.main(BasicConnectionDemo.java:42)

Exception in thread "main" java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)

Exception in thread "main" java.lang.ClassNotFoundException: com.mysql.jdbc.Driver  分别是无法登陆和找不到驱动。

可是不用properties是可以登陆的。

于是我又测试了一下从db.properties读出来的是什么东西

System.out.println("driver:"+driver);
                System.out.println("password:"+password);
                System.out.println("username:"+username);
                System.out.println("url:"+url);
                  
                System.out.println("driver的类型:"+driver.getClass());
                System.out.println("password的类型:"+password.getClass());
                System.out.println("username的类型:"+username.getClass());
                System.out.println("url的类型:"+url.getClass());
结果显示的都是字符串类型，而且值又和直接对字符串赋的值一样的。

但为什么还是无法登陆了？。后来抱着试一试的态度

我又发现db.properties的每一行都有空格，删掉，就成功了

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/bookstore
username=root
password=727272