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Re: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Posted by: Lin klinmy
Date: July 19, 2008 01:29AM

Hi, I got the same problem last time.

But I kill it!!

Look at my Exception while use jdbc.

///////////////////////////////////////////////////////////////////
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 0 ms ago.
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:406)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2103)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
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:406)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at com.kag.db.DBConnection.<init>(DBConnection.java:80)
at com.kag.db.DBConnection.getConnection(DBConnection.java:94)
at com.kag.db.DBConnection.main(DBConnection.java:227)
Caused by: java.net.UnknownHostException: host
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:849)
at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1200)
at java.net.InetAddress.getAllByName0(InetAddress.java:1153)
at java.net.InetAddress.getAllByName(InetAddress.java:1083)
at java.net.InetAddress.getAllByName(InetAddress.java:1019)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:243)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:280)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2026)
... 14 more
2008-7-19 15:10:39 com.kag.db.DBConnection <init>
warning: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 0 ms ago.
/////////////////////////////////////////////////////

I set the database name as: "jdbc:mysql://host:3306/test";
Look at the exception message: "Caused by: java.net.UnknownHostException: host".

So, Just change "host to localhost", it works!!!!

There may be something wrong with host or port .
Such as "error host" or "error port"(may be port was used!) !
Change it when needed,it may work!!

Look at the exception ,maybe there is a answer!!

Good Luck!!!!!

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Re: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
July 19, 2008 01:29AM


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