java - 连接失败!检查输出控制台

Question

在 mac Yosemite 上使用 java 连接到 mysql 数据库，并连接到 CLASS PATH 中 jdbcdriver jar 文件的完整 url。 netbeans 控制台给出“java.sql.SQLException:用户'root'@'localhost'访问被拒绝(使用密码:YES)”。试了很多论坛的方法，还是不行。

这是我的代码

//STEP 1. Import required packages
import java.sql.*;

public class JDBCExample {
   // JDBC driver name and database URL
   static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";  
   static final String DB_URL = "jdbc:mysql://localhost:3307/library";

   //  Database credentials
   static final String USER = "root";
   static final String PASS = "default$";

   public static void main(String[] args) {
   Connection conn = null;
   Statement stmt = null;
   ResultSet rs = null;
   try{
      //STEP 2: Register JDBC driver (automatically done since JDBC 4.0)
      Class.forName("com.mysql.jdbc.Driver");

      //STEP 3: Open a connection
      System.out.println("Connecting to database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);

      //STEP 4: Execute a query
      System.out.println("Creating database...");
      stmt = conn.createStatement();
      rs = stmt.executeQuery("select uid uname from User");

      //STEP 5: Process the results
      while(rs.next()){
          System.out.println("User ID="+rs.getInt("uid")+", Name="+rs.getString("uname"));
      }

   }catch(SQLException se){
      //Handle errors for JDBC
      se.printStackTrace();
   }catch(Exception e){
      //Handle errors for Class.forName
      e.printStackTrace();
   }finally{
      //finally block used to close resources
      try{
         if(stmt!=null)
            stmt.close();
      }catch(SQLException se2){
      }// nothing we can do
      try{
         if(conn!=null)
            conn.close();
      }catch(SQLException se){
         se.printStackTrace();
      }//end finally try
   }//end try
   System.out.println("Goodbye!");
}//end main
}//end JDBCExample

结果如下:

Connection Failed! Check output console
java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:959)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3870)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3806)
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:871)
    at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1686)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1207)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2254)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2285)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2084)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:795)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:400)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:327)
    at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:422)
    at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:134)
    at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:105)
    at cs157a_test.DataSourceTester.main(DataSourceTester.java:54)

Answer 1

您得到的异常是告诉您已成功连接到服务器，但是不允许/授予用户root从localhost连接。

您必须检查 mysql 用户权限表，并确保有一行允许 root 使用正确的密码从 localhost 连接。

以下 SQL 将显示这一点:

SELECT host, user FROM mysql.user;

如果存在 root 和 localhost 或 root 和 % 的行，那么您必须重置您的使用此 SQL 的密码:

set password for 'root'@'localhost' = password('your_password');

如果没有行，您必须创建它，然后设置要使用该用户访问的数据库的权限。

您可以使用以下 SQL 来实现此目的:

CREATE USER 'root'@'localhost' IDENTIFIED BY 'your_password';
GRANT ALL ON YOU_DATABASES.* TO 'root'@'localhost';

最后你必须刷新权限或重新启动 mysql。再试一次，确保您能够连接。