Here is the error.
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: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:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:355)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2461)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2498)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2283)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:822)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
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:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:404)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:317)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at eventmanagementsystem.infinity.dbHandler.buildConnection(dbHandler.java:43)
at eventmanagementsystem.infinity.dbHandler.getParticipantResultSet(dbHandler.java:395)
at eventmanagementsystem.infinity.ParticipantList.populateList(ParticipantList.java:96)
at eventmanagementsystem.infinity.EMS.<init>(EMS.java:31)
at eventmanagementsystem.infinity.EventManagementSystemInfinity.main(EventManagementSystemInfinity.java:25)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at java.net.Socket.<init>(Socket.java:434)
at java.net.Socket.<init>(Socket.java:244)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:305)
... 19 more
May 24, 2015 3:48:58 PM eventmanagementsystem.infinity.EMS <init>
SEVERE: null
java.lang.NullPointerException
at eventmanagementsystem.infinity.dbHandler.getParticipantResultSet(dbHandler.java:396)
at eventmanagementsystem.infinity.ParticipantList.populateList(ParticipantList.java:96)
at eventmanagementsystem.infinity.EMS.<init>(EMS.java:31)
at eventmanagementsystem.infinity.EventManagementSystemInfinity.main(EventManagementSystemInfinity.java:25)
BUILD SUCCESSFUL (total time: 21 seconds)
Here is the code.
public static Connection buildConnection()
{
try{
//Class.forName("org.apache.derby.jdbc.ClientDriver");
//Class.forName("oracle.jdbc.driver.OracleDriver");
Class.forName("com.mysql.jdbc.Driver");
//String connString = "jdbc:derby://localhost:4040/EventManagementSystem";
//String username = "Event";
//String password = "event";
//String username = "system";
//String password = "a1234";
String JDBC_DRIVER = "com.mysql.jdbc.Driver";
String DB_URL = "jdbc:mysql://localhost:3306/user";
String USER = "root";
String PASS = "a1234";
//Connection conn = DriverManager.getConnection(connString,username,password);
//Connection conn = DriverManager.getConnection("jdbc:oracle:thin:#oracle-prod:1521:OPROD",username,password);
Connection conn = DriverManager.getConnection(DB_URL,USER,PASS);
return conn;
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
I think the problem is with the DB_URL but I am not very sure. I have added mysql-connector jar as well. It cannot access the database that I have created. The error list also shows that connection is refused but I am not sure why is that so.
Related
Hello I'm trying to update my app on heroku. When I build my app this error appears:
Caused by: java.lang.NullPointerException: null
at java.net.URI$Parser.parse(URI.java:3042) ~[na:1.8.0_221]
at java.net.URI.<init>(URI.java:588) ~[na:1.8.0_221]
at pl.jawegiel.util.DbUtil.getConnection(DbUtil.java:19) ~[classes/:na]
at pl.jawegiel.dao.UsersBasicInfoDao.<init>(UsersBasicInfoDao.java:17) ~[classes/:na]
at pl.jawegiel.dao.UsersDao.<init>(UsersDao.java:27) ~[classes/:na]
at pl.jawegiel.listener.SessionListener.<init>(SessionListener.java:19) ~[classes/:na]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_221]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_221]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_221]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_221]
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:172) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
... 64 common frames omitted
where my DbUtil class looks like this:
public class DbUtil {
public static Connection getConnection() throws URISyntaxException, SQLException {
URI dbUri = new URI(System.getenv("DATABASE_URL"));
String username = dbUri.getUserInfo().split(":")[0];
String password = dbUri.getUserInfo().split(":")[1];
String dbUrl = "jdbc:postgresql://" + dbUri.getHost() + ':' + dbUri.getPort() + dbUri.getPath();
return DriverManager.getConnection(dbUrl, username, password);
}
}
I did exactly as Heroku tutorial says but in vain. Help me please.
It is because of this line
System.getenv("DATABASE_URL")
The program could not find the system environment variable on heroku.
You will have to add the environment variable value using config var or set define database url inside the class and use it.
Help me! I have a restful API link, I used Postman tool call success, but when I code on eclipse a Restful client, it's fail. I tried on off proxy, but not success.
public class JersyGetClient {
public static void main(String[] args) {
String url = "https://abc.custhelp.com/services/rest/connect/v1.4/accounts";
String name = "thai.hoangan";
String password = "123456a#";
String authString = name + ":" + password;
String authStringEnc = new BASE64Encoder().encode(authString.getBytes());
System.out.println("Base64 encoded auth string: " + authStringEnc);
Client restClient = Client.create();
WebResource webResource = restClient.resource(url);
ClientResponse resp = webResource.accept("application/json")
.header("Authorization", "Basic " + authStringEnc)
.header("OSvC-CREST-Application-Context", "asd")
.get(ClientResponse.class);
if (resp.getStatus() != 200) {
System.err.println("Unable to connect to the server");
}
String output = resp.getEntity(String.class);
System.out.println("response: " + output);
}
}
Output:
Exception in thread "main" com.sun.jersey.api.client.ClientHandlerException:
java.net.ConnectException: Connection timed out: connect
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:155)
at com.sun.jersey.api.client.Client.handle(Client.java:652)
at com.sun.jersey.api.client.WebResource.handle(WebResource.java:682)
at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74)
at com.sun.jersey.api.client.WebResource$Builder.get(WebResource.java:509)
at JersyGetClient.main(JersyGetClient.java:22)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:668)
at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:264)
at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1105)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:999)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1513)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1441)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:338)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler._invoke(URLConnectionClientHandler.java:253)
at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:153)
... 5 more
Oh, I resolved, Just add:
System.setProperty("https.proxyHost", "proxytest.vcb");
System.setProperty("https.proxyPort", "8080");
I just instaled MySQL server and made one database using Terminal- on ubuntu, and the server works, my database is shown properly and my table is shown also properly.
But when I try to run a program in eclipse, it trows an exception. First was a SSL exception which I fixed with ?autoReconnect=true&useSSL=false.
So now, I get another exception. It says it can not connect to database and gives up after three tries.
I also tried some solutions from this forum, but with no success.
...
Im using drivers version 5.1.42.
Any solutions?
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class MySql {
public static void main(String[] args) throws Exception {
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Imenik?autoReconnect=true&useSSL=false","root","******");
PreparedStatement ps = conn.prepareStatement("select * from imenik");
ResultSet result = ps.executeQuery();
while(result.next()) {
System.out.println(result.getString(1) + " " +result.getString(2) + " " +result.getString(3) );
}
}}
And this would be an exception:
Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
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:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2029)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:779)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
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:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at MySql.main(MySql.java:11)
Caused by: java.sql.SQLException: Unknown system variable
'query_cache_size'
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2486)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2444)
at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1381)
at com.mysql.jdbc.ConnectionImpl.loadServerVariables(ConnectionImpl.java:3766)
at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3229)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2067)
... 13 more
It might be problem of your given password for the database, you can use below solution:
Class.forName("com.mysql.cj.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/Imenik?autoReconnect=true&useSSL=false","root","root");
PreparedStatement ps = (PreparedStatement) conn.prepareStatement("select * from imenik");
ResultSet result = ps.executeQuery();
while(result.next()) {
System.out.println(result.getString(1) + " " +result.getString(2) + " " +result.getString(3) );
}
tested with mysql-connector-java-6.0.6.jar
This is my code
public class Email {
static Properties props;
public static void main(String[] args){
String from = "some email";
String to= "some other email";
String host = "localhost";
props = System.getProperties();
props.setProperty("mail.host", host);
props.put("mail.transport.protocol", "smtp");
Session session = Session.getDefaultInstance(props,null);
try{
MimeMessage message = new MimeMessage(session);
message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
message.setSubject("This is the Subject Line!");
message.setText("This is actual message");
Transport.send(message);
System.out.println("Sent message successfully....");
}catch (MessagingException mex) {
mex.printStackTrace();
}
}
}
I am getting following exception:
javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
nested exception is:
java.net.ConnectException: Connection refused
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1961)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:654)
at javax.mail.Service.connect(Service.java:295)
at javax.mail.Service.connect(Service.java:176)
at javax.mail.Service.connect(Service.java:125)
at javax.mail.Transport.send0(Transport.java:194)
at javax.mail.Transport.send(Transport.java:124)
at com.cisco.ci.support.email.Email.main(Email.java:51)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:321)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:237)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1927)
... 12 more
It seems that I do not have smtp server on my mac? any solutions?
You either need to install a smtp Server on your mac, which is not that simple, or use an existing smtp server. Obviously you will need an account for that server, as there are not many smtp Servers without authentication in the wild.
E.g. Create a googlemail Account, then check: http://www.mkyong.com/java/javamail-api-sending-email-via-gmail-smtp-example/ for example of how to use it!
I am working on a RMI client, but when I try to connect to it from any machine but localhost it gets a refused connection stack trace. I verified that my firewall is off. What else do I need to do?
Here is my code
public class FrontManagerClient {
boolean state;
String command;
String value;
public FrontManagerClient(String cmd,String value) {
this.command=cmd;
this.value=value;
}
public boolean getCommand() throws RemoteException, NotBoundException, MalformedURLException{
FrontPanelManagerIntrface f=(FrontPanelManagerIntrface)Naming.lookup("lookup=//localhost//frontPanelRequestControllerService");
state=f.Communicate(command, value);
return state;
}
public static void main(String[] args) throws RemoteException, NotBoundException, MalformedURLException {
FrontManagerClient f = new FrontManagerClient("Password_Enter", "admin");
System.out.println(""+f.getCommand());
}
}
when i run the server and run the client ,it displays this error message
Exception in thread "main" java.rmi.ConnectException: Connection refused to host: 10.96.28.6; nested exception is:
java.net.ConnectException: Connection refused: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:619)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:216)
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:202)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:340)
at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source)
at java.rmi.Naming.lookup(Naming.java:101)
at doormanager.FrontManagerClient.getCommand(FrontManagerClient.java:30)
at doormanager.FrontManagerClient.main(FrontManagerClient.java:37)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:208)
at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:40)
at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:146)
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:613)
... 7 more
Java Result: 1
There is no RMI Registry running at the host 10.96.28.6, or you haven't fixed your firewall.