String connection = "jdbc:mysql://%s:%s/%s?useUnicode=true&characterEncoding=UTF-8";
conn = DriverManager.getConnection(String.format(connecti on, "x.x.x.x", "3306", "schoolController"), "user", "passwd");
System.out.println("OK");
st = conn.createStatement();
یه هفته هست هس با کد مشکل دارم اصلا به دیتابیس متصل نمیشه.
خطا:
Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsExce ption: 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.newInsta nce0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInsta nce(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newI nstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Construc tor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:41 1)
at com.mysql.jdbc.SQLError.createCommunicationsExcept ion(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:355)
at com.mysql.jdbc.ConnectionImpl.coreConnect(Connecti onImpl.java:2461)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(Co nnectionImpl.java:2498)
at com.mysql.jdbc.ConnectionImpl.createNewIO(Connecti onImpl.java:2283)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImp l.java:822)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connect ion.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInsta nce0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInsta nce(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newI nstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Construc tor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:41 1)
at com.mysql.jdbc.ConnectionImpl.getInstance(Connecti onImpl.java:404)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonReg isteringDriver.java:317)
at java.sql.DriverManager.getConnection(DriverManager .java:664)
at java.sql.DriverManager.getConnection(DriverManager .java:247)
at schoolcontroller.tools.DataBase.mysql.DataAccess.c onnect(DataAccess.java:45)
at schoolcontroller.tools.DataBase.mysql.DataAccess.m ain(DataAccess.java:40)
هم اسم دیتابیس هم ای پی سرور و هم یوزرنیم و پسورد درسته و به راحتی با نرم افزار Mysql Workbench میتونم به سرور متصل بشم.
نسخه MySQL Server :
5.7.19-0ubuntu0.16.04.1