如何检查默认端口号为mysql连接？连接不工作！ jdbc连接 [英] How to check the default port number for mysql connection? Connection not working! jdbc connection

问题描述

我试图使用jdbc在java文件中连接数据库。它没有连接，给我不断的错误出了问题;我想这是因为端口号，因为所有其他数据，如用户名，密码和其他代码似乎是正确的。

I am trying to connect with database using jdbc in java file. It is not connecting at all and giving me the error constantly "Something went wrong"; I guess it is because of the port number because all other data such as username, password and other code seems correct.

我想检查默认端口号，以便我可以正确地尝试。我尝试使用这三个8080,80和3306，但它显示我的错误。

I want to check the default port number so that I can try it properly. I did try using all three of these 8080, 80 and 3306 but it shows me error.

这里端口8080用于HTTP服务器，3306应该是研究默认的，80是随机的。

Here port 8080 is used for HTTP server, 3306 is supposed to be default from the research and 80 randomly.

try {
        Class.forName("com.mysql.jdbc.Driver");
        System.out.println("Driver found");
    } catch (ClassNotFoundException e) {
        System.out.println("Driver not found");
    }

    String url="jdbc:mysql://localhost:8080 or 80 or 3306 or without port number/test";
    String user="user";
    String password="";

    Connection con=null;

    try {
        con=DriverManager.getConnection(url, user, password);
    System.out.println("Success");
    } catch (SQLException e){
         e.printStackTrace();
    }
}

使用时出现错误String url = jdbc：mysql：// localhost：3306 / test;

The error is giving below when used String url="jdbc:mysql://localhost:3306/test";

  Driver found
  com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

   The last packet sent successfully to the server was 0 milliseconds ago. The driver has not     received any packets from the server.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1036)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2232)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2265)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2064)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:790)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:395)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at com.town.connect.Dbconnection.main(Dbconnection.java:26)
  Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:382)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:241)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:228)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:431)
at java.net.Socket.connect(Socket.java:527)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:213)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:297)
... 15 more

推荐答案

您可以通过

mysql> show variables;

这篇关于如何检查默认端口号为mysql连接？连接不工作！ jdbc连接的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！