[Solved] IDEA Remote Operate hdfs Hadoop Error: Caused by: java.net.ConnectException: Connection refused: no further information

DEA remote operation HDFS Hadoop

Idea remote operation HDFS Hadoop, error caused by: Java net. ConnectException: Connection refused: no further information

1.source code

package com.github.td.hdfs;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.junit.Test;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;

/**
 * @Description: TODO
 * @Author: 
 * @DateTime: 2021/12/20 17:52
 **/
public class HdfsClient {

    @Test
    public void testMkdirs() throws IOException, URISyntaxException, InterruptedException{

        // 1 Get the system of the files
        Configuration configuration = new Configuration();
        // master == 192.168.xx.xx
        // the port of cdh version is 8020, the port of common version Hadoop is 9000.
        FileSystem fs = FileSystem.get(new URI("hdfs://master:8020"), configuration, "root");

        // 2 Create Directory
        fs.mkdirs(new Path("/hadoop/hdfs-api"));

        // 3 Close resouce
        fs.close();
    }
}

2. Error report log

java.net.ConnectException: Call From to master: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:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:831)
	at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:755)
	at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1549)
	at org.apache.hadoop.ipc.Client.call(Client.java:1491)
	at org.apache.hadoop.ipc.Client.call(Client.java:1388)
	at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:233)
	at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:118)
	at com.sun.proxy.$Proxy12.mkdirs(Unknown Source)
	at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.mkdirs(ClientNamenodeProtocolTranslatorPB.java:657)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:422)
	at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:165)
	at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:157)
	at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:359)
	at com.sun.proxy.$Proxy13.mkdirs(Unknown Source)
	at org.apache.hadoop.hdfs.DFSClient.primitiveMkdir(DFSClient.java:2420)
	at org.apache.hadoop.hdfs.DFSClient.mkdirs(DFSClient.java:2396)
	at org.apache.hadoop.hdfs.DistributedFileSystem$27.doCall(DistributedFileSystem.java:1319)
	at org.apache.hadoop.hdfs.DistributedFileSystem$27.doCall(DistributedFileSystem.java:1316)
	at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
	at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirsInternal(DistributedFileSystem.java:1333)
	at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirs(DistributedFileSystem.java:1308)
	at org.apache.hadoop.fs.FileSystem.mkdirs(FileSystem.java:2275)
	at com.github.td.hdfs.HdfsClient.testMkdirs(HdfsClient.java:29)
	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:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
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:715)
	at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
	at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531)
	at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:700)
	at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:804)
	at org.apache.hadoop.ipc.Client$Connection.access$3800(Client.java:421)
	at org.apache.hadoop.ipc.Client.getConnection(Client.java:1606)
	at org.apache.hadoop.ipc.Client.call(Client.java:1435)
	... 46 more

3. cause analysis

Port problem

In the CDH environment, HDFS is port 8020, conf.set (“FS. Defaultfs”“ hdfs://192.168.0.4:8020 ”);

In a normal Hadoop environment, HDFS is a 9000 port, conf.set (“FS. Defaultfs”“ hdfs://192.168.0.121:9000 ”);

4. Solutions

Modify the port number to 9000

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