I am trying to port my code from linux to mac OSX LION. The following method works on linux just fine.
Connection getConnection() throws SQLException{
String url = "jdbc:mysql://localhost/";
return DriverManager.getConnection(url, "root", "mypassword");
}
But it's not working on my mac. I am using XAMMP so the path to my database is /Applications/XAMPP/xamppfiles/bin/mysql. The error I get reads
Exception in thread "main" java.sql.SQLException:
No suitable driver found for jdbc:mysql://localhost/
at java.sql.DriverManager.getConnection(DriverManager.java:602)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
UPDATES BASED ON FEEDBACK FROM POSTS BELOW:
I downloaded the jar and add it to the project's build path. When I try to add Class.forName("com.mysql.jdbc.Driver") I get compile error so I comment it out. Then I run the program to get the following error:
Exception in thread "main" 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:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:350)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2408)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2445)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2230)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
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:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at learning.database.Classroom.getConnection(Classroom.java:42)
at learning.database.Classroom.main(Classroom.java:239)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:432)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at java.net.Socket.<init>(Socket.java:375)
at java.net.Socket.<init>(Socket.java:218)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:300)
... 16 more
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)
The JAVA JDK does not come with specific SQL drivers(i.e mySQL, postgre, MS SQL, etc). You need to download and install them separately. The download link for the java mysql connector can be found here:
http://dev.mysql.com/downloads/connector/j/
It says to put the driver in your class path, but you can also put it in your IDE's build path, it might be easier depending on what you are doing.
Make sure the mysql jdbc connector is in the CLASSPATH. You probably also need to load the driver, adding the following line before trying to get the connection:
Class.forName("com.mysql.jdbc.Driver");
You need to have you mysql jdbc connector jar on the classpath for your mac.
Related
When attempting to do this in my code:
Class.forName("com.mysql.jdbc.Driver");
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/MazeJumperLeaderboardDB", "root", "password");
I always seem to get this error no matter what I try:
java.sql.SQLException: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
at com.mysql.jdbc.ConnectionImpl.buildCollationMapping(ConnectionImpl.java:1062)
at com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3556)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2513)
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:423)
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)
... 61 more
I am using Java NetBeans IDE 8.2 and using MySQL Connector Java 8.0.18.
I have looked at other questions, notably this one:
ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long on connect to MySQL
But, doing this resulted in the same 'java.sql.SQLException: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.lang.Long' error.
Furthermore, I seem to be able to connect to my database driver just fine, but when attempting to connect to the MySQL server, it displays an error message with the same error yet again.
I'm really not sure what else to try at this point, so any help would be greatly appreciated!
I managed to (finally) solve my issue.
The problem was with the pre-installed JDBC driver on NetBeans. The pre-installed JDBC driver was of version 5.1.23, which is outdated and did not match up with my installed JDBC driver from the MySQL website.
So, what I did was:
I deleted the pre-installed driver in the 'Libraries' folder on NetBeans (under your project, the libraries folder), then right clicked on my project, selected 'Properties', then 'Libraries', then I clicked 'Add JAR/Folder', then browsed through my system files and searched for the latest version of MySQL Connector that I had downloaded (Connector/J 8.0.18), and then I added the .zip file. Then I went over to the services tab, and re-established the connection to the database and drivers using the SAME MySQL Connector version, and then it worked and stopped giving me this error.
This question already has answers here:
Can't connect to MySQL from Java: NullPointerException inside MySQL driver connection logic
(5 answers)
Closed 4 years ago.
I'm new in Databases just started to learn them. I have MySQL Server 8.0., Workbench 8.0, Java connector 5.1.31, Java 1.8 itself. Followed multiple guides for newbies how to start with.
So there is the case. I have database on localhost and successfully connect to it with workbench and via windows prompt. But after I execute code in java:
Driver sqlDriver = new FabricMySQLDriver();
DriverManager.registerDriver(sqlDriver);
Connection sqlConnection = DriverManager.getConnection("jdbc:mysql://localhost:3306/?user=root", "root", "root");
I get exception com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
Why it could happen? I've tried to reinstall MySQL, Cleaned OS variables, looked everywhere and couldn't find solution. Would be glad to find it here.
UPD:
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:408)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1023)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:997)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:983)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:928)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2407)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2328)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
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:408)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.company.Main.main(Main.java:11)
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ConnectionImpl.getServerCharacterEncoding(ConnectionImpl.java:3309)
at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1985)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1911)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1288)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2508)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2346)
... 13 more
The problem is the compatibility of older versions of MySQL Connector/J with MySQL 8. You need to upgrade to either MySQL Connector/J 5.1.46 or - better - 8.0.11 (or a higher version).
In my case, I was using Maven Dependency to use JDBC connector. I just changed the version of dependency. This worked for me
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>
Add the below version and you will be fine:
<mysql.driver.version>8.0.20</mysql.driver.version>
I am working with PlayFramework (2.3.x) application. I wanted to connect to a mysql db. Below is the configuration that I had given in application.conf:
db.default.driver="com.mysql.jdbc.Driver"
db.default.url="jdbc:mysql://localhost/mydb"
db.default.jndiName=DefaultDS
db.default.username=root
db.default.password=root
db.default.logStatements=true
jpa.default=defaultPersistenceUnitName
When I run the application I am getting the following exception
Oops, cannot start the server.
Configuration error: Configuration error[Cannot connect to database [default]]
at play.api.Configuration$.play$api$Configuration$$configError(Configuration.scala:94)
at play.api.Configuration.reportError(Configuration.scala:743)
at play.api.db.BoneCPPlugin$$anonfun$onStart$1.apply(DB.scala:247)
at play.api.db.BoneCPPlugin$$anonfun$onStart$1.apply(DB.scala:238)
at scala.collection.immutable.List.map(List.scala:273)
at play.api.db.BoneCPPlugin.onStart(DB.scala:238)
at play.api.Play$$anonfun$start$1$$anonfun$apply$mcV$sp$1.apply(Play.scala:91)
at play.api.Play$$anonfun$start$1$$anonfun$apply$mcV$sp$1.apply(Play.scala:91)
at scala.collection.immutable.List.foreach(List.scala:381)
at play.api.Play$$anonfun$start$1.apply$mcV$sp(Play.scala:91)
at play.api.Play$$anonfun$start$1.apply(Play.scala:91)
at play.api.Play$$anonfun$start$1.apply(Play.scala:91)
at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
at play.api.Play$.start(Play.scala:90)
at play.core.StaticApplication.<init>(ApplicationProvider.scala:55)
at play.core.server.NettyServer$.createServer(NettyServer.scala:253)
at play.core.server.NettyServer$$anonfun$main$3.apply(NettyServer.scala:289)
at play.core.server.NettyServer$$anonfun$main$3.apply(NettyServer.scala:284)
at scala.Option.map(Option.scala:146)
at play.core.server.NettyServer$.main(NettyServer.scala:284)
at play.core.server.NettyServer.main(NettyServer.scala)
Caused by: java.sql.SQLException: Access denied for user ''#'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:998)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3847)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:871)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1665)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1207)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2249)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2280)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2079)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44)
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:422)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.jolbox.bonecp.BoneCP.obtainRawInternalConnection(BoneCP.java:363)
at com.jolbox.bonecp.BoneCP.<init>(BoneCP.java:416)
at com.jolbox.bonecp.BoneCPDataSource.getConnection(BoneCPDataSource.java:120)
at play.api.db.BoneCPPlugin$$anonfun$onStart$1.apply(DB.scala:240)
... 18 more
I have my db created and I am able to use with mysql console.
I have my persistence.xml placed in my conf/META-INF. Below is the persistence.xml
I have root user with all privileges.
Could anyone help me with this?
According to the docs for Play 2.3.x, the correct configuration is db.default.user and not db.default.username. That is probably the cause of the exception. So change your configuration to:
db.default.driver="com.mysql.jdbc.Driver"
db.default.url="jdbc:mysql://localhost/mydb"
db.default.jndiName=DefaultDS
db.default.user=root
db.default.password=root
db.default.logStatements=true
jpa.default=defaultPersistenceUnitName
You are not passing a login, as indicated by the line
Caused by: java.sql.SQLException: Access denied for user ''#'localhost' (using password: YES)
These days I do exercise about JDBC.When the Java project connect the MySQL，then it's Ok.But the JavaEE project which run on MyEclipse cann't connect to MySQL,these is the error messages:
严重: create connection error
java.sql.SQLException: Access denied for user 'root'#'localhost' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4074)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4006)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:919)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1694)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1244)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2397)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2430)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2215)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:813)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.GeneratedConstructorAccessor14.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:334)
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:142)
at com.alibaba.druid.filter.stat.StatFilter.connection_connect(StatFilter.java:211)
at com.alibaba.druid.filter.FilterChainImpl.connection_connect(FilterChainImpl.java:136)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1271)
at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1325)
at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1215).
The import thing:I try to grand,restart the mysql and so on.But all of them are failed.
MySql default password is root try it, or using the "" for password.
Thanks everyone.I solve my problem.Followings are the ways:
(1:To install a newest MyEclipse software.)
2.To install a newest Tomcat7.0.64.(Warning:this is the most important way I have to solve my problem).
I'm trying to submit a job (a simple word count) to hadoop-2.5.0 (installed on a ubuntu 14.04.1 server running on a virtual machine) from eclipse on windows. In the job configuration, i've set "fs.defaultFS" to "hdfs://192.168.2.216:8020" (as suggested in this thread) but when I run the main progam I got the following exception:
WARN - NativeCodeLoader - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
ERROR - Shell - Failed to locate the winutils binary in the hadoop binary path
Exception in thread "main" java.net.ConnectException: Call From EL-OUED/192.168.2.8 to 192.168.2.216:8020 failed on connection exception: java.net.ConnectException: Connection refused: no further information; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:783)
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:730)
at org.apache.hadoop.ipc.Client.call(Client.java:1414)
at org.apache.hadoop.ipc.Client.call(Client.java:1363)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:206)
at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:190)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:103)
at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:699)
at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1762)
at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1124)
at org.apache.hadoop.hdfs.DistributedFileSystem$17.doCall(DistributedFileSystem.java:1120)
at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1120)
at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:1398)
at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:145)
at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:458)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:343)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1285)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1282)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1556)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1282)
at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1303)
at com.heavenize.hadoop.WordCountMR.main(WordCountMR.java:55)
Caused by: java.net.ConnectException: Connection refused: no further information
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:735)
at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:529)
at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:493)
at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:604)
at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:699)
at org.apache.hadoop.ipc.Client$Connection.access$2800(Client.java:367)
at org.apache.hadoop.ipc.Client.getConnection(Client.java:1462)
at org.apache.hadoop.ipc.Client.call(Client.java:1381)
... 28 more
Also, when checking connection configuration on hadoop, it seems it is listening/accepting for connections on 127.0.0.1:8020.
$netstat -lent | grep 8020
tcp 0 0 127.0.0.1:8020 0.0.0.0:* LISTEN 1001 10380
This is the content of core-site.xml, I wonder if it is the source of this problem and how to fix it?
<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://localhost</value>
</property>
</configuration>
Basically your namenode is listening on the localhost interface, therefore it allows connections only from 127.0.0.1. As you suggested, the error is indeed in the fs.default.name parameter, which should be modified to use the hostname instead of localhost.
Beware that /etc/hosts should contain a line like
192.168.2.216 hostname.fully.qualified.domain.com hostname
You can verify that the hostname is properly setting running the command "hostname" and "hostname -f". "hostname" should return the the name of the system as returned by gethostname, while "hostname -f" should return the fqdn of the system.