database connectivity - java.net.UnknownHostException
Solution 1
You have missed the colon between hostname and port number... Your connection URL should be
String URL_connection="jdbc:mysql://localhost:3306/vendor";
Solution 2
I think the connection URL should be jdbc:mysql://localhost:3306/vendor
. localhost
is the server name and 3306
the port name separated by :
.
String URL_connection="jdbc:mysql://localhost:3306/vendor";
Please go through the docs.
The JDBC URL format for MySQL Connector/J is as follows, with items in square brackets ([, ]) being optional:
jdbc:mysql://[host][,failoverhost...][:port]/[database] »
[?propertyName1][=propertyValue1][&propertyName2][=propertyValue2]...
If the host name is not specified, it defaults to 127.0.0.1. If the port is not specified, it defaults to 3306.
Comments
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uLYsseus almost 2 years
I have an exception here in the following code... I am trying to build a simple servlet project and I have the following exception raised:
java.net.UnknownHostException
...
I have the mysql jar file added and besides...I have added it as an external jar file and also under lib in WEB-INF, as stated in this page, but now this is throwing anjava.net.UnknownHostException
.This is the code and the exception stack trace.
package com.servlet.Mysql; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class Connection_Class { String driver_ClassName="com.mysql.jdbc.Driver"; String URL_connection="jdbc:mysql://localhost3306/vendor"; String user="root"; String password="lifesuckzz"; private static Connection_Class connectionclass=null; private Connection_Class(){ try{ Class.forName(driver_ClassName); }catch(ClassNotFoundException e){ e.printStackTrace(); } } public Connection getConnection() throws SQLException{ Connection con=null; con=DriverManager.getConnection(URL_connection,user,password); return con; } public static Connection_Class getInstance(){ if(connectionclass==null){ connectionclass=new Connection_Class(); } return connectionclass;}}
Stack trace:
com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** java.net.UnknownHostException MESSAGE: localhost3306 STACKTRACE: java.net.UnknownHostException: localhost3306 at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$1.lookupAllHostAddr(Unknown Source) at java.net.InetAddress.getAddressesFromNameService(Unknown Source) at java.net.InetAddress.getAllByName0(Unknown Source) at java.net.InetAddress.getAllByName(Unknown Source) at java.net.InetAddress.getAllByName(Unknown Source) at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:133) at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280) at com.mysql.jdbc.Connection.createNewIO(Connection.java:1699) at com.mysql.jdbc.Connection.<init>(Connection.java:405) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at com.servlet.Mysql.Connection_Class.getConnection(Connection_Class.java:25) at com.servlet.Mysql.LoginServlet.doGet(LoginServlet.java:49) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) ** END NESTED EXCEPTION ** at com.mysql.jdbc.Connection.createNewIO(Connection.java:1764) at com.mysql.jdbc.Connection.<init>(Connection.java:405) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:268) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at com.servlet.Mysql.Connection_Class.getConnection(Connection_Class.java:25) at com.servlet.Mysql.LoginServlet.doGet(LoginServlet.java:49) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)
I am using Apache Web container and Eclipse, this post java.lang.ClassNotFoundException in spite of using CLASSPATH environment variable I think wasnt near to my case here.....please help me out, thank you all in advance...
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Amit almost 11 yearsSome times it happens buddy... We are all same.... You can upvote the answer if it helped you..