由於本地測試和服務器不在一個局域網,安裝的hadoop配置文件是以內網ip作為機器間通信的ip.

在這種情況下,我們能夠訪問到namenode機器,

namenode會給我們數據所在機器的ip地址供我們訪問數據傳輸服務,

但是返回的的是datanode內網的ip,我們無法根據該IP訪問datanode服務器.

報錯如下

2018-06-06 17:01:44,555 [main] WARN  [org.apache.hadoop.hdfs.BlockReaderFactory] - I/O error constructing remote block reader.
java.net.ConnectException: Connection timed out: no further information
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717
 
)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531)
    at org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:3450)
    at org.apache.hadoop.hdfs.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:777
 
)
    at org.apache.hadoop.hdfs.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:694)
    at org.apache.hadoop.hdfs.BlockReaderFactory.build(BlockReaderFactory.java:355)
    at org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:665)
    at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:874
 
)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:926)
    at java.io.DataInputStream.read(DataInputStream.java:149)
    at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
    at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
    at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
    at java.io.InputStreamReader.read(InputStreamReader.java:184)
    at java.io.BufferedReader.fill(BufferedReader.java:161)
    at java.io.BufferedReader.readLine(BufferedReader.java:324)
    at java.io.BufferedReader.readLine(BufferedReader.java:389)
    at com.feiyangshop.recommendation.HdfsHandler.main(HdfsHandler.java:36)
2018-06-06 17:01:44,560 [main] WARN  [org.apache.hadoop.hdfs.DFSClient] - Failed to connect to /192.168.1.219:50010 for block, add to deadNodes and continue. java.net.ConnectException: Connection timed out: no further information
java.net.ConnectException: Connection timed out: no further information
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531)
    at org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:3450)
    at org.apache.hadoop.hdfs.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:777)

為了能夠讓開發機器訪問到hdfs,我們可以通過域名訪問hdfs.

讓namenode返回給我們datanode的域名,在開發機器的hosts文件中配置datanode對應的外網ip和域名,並且在與hdfs交互的程序中添加如下代碼即可

import org.apache.hadoop.conf.Configuration;

Configuration conf = new Configuration();
//設置通過域名訪問datanode
conf.set("dfs.client.use.datanode.hostname", "true");

windows bug

還有一個就是比較常見的bug

Exception in thread "main" java.lang.UnsatisfiedLinkError: org.apache.hadoop.util.NativeCrc32.nativeComputeChunkedSums(IILjava/nio/ByteBuffer;ILjava/nio/ByteBuffer;IILjava/lang/String;JZ)V
    at org.apache.hadoop.util.NativeCrc32.nativeComputeChunkedSums(Native Method)
    at org.apache.hadoop.util.NativeCrc32.verifyChunkedSums(NativeCrc32.java:59)
    at org.apache.hadoop.util.DataChecksum.verifyChunkedSums(DataChecksum.java:301)
    at org.apache.hadoop.hdfs.RemoteBlockReader2.readNextPacket(RemoteBlockReader2.java:231)
    at org.apache.hadoop.hdfs.RemoteBlockReader2.read(RemoteBlockReader2.java:152)
    at org.apache.hadoop.hdfs.DFSInputStream$ByteArrayStrategy.doRead(DFSInputStream.java:767)
    at org.apache.hadoop.hdfs.DFSInputStream.readBuffer(DFSInputStream.java:823)
    at org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:883)
    at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:926)
    at java.io.DataInputStream.read(DataInputStream.java:149)

windows中的HADOOP_HOME裏的bin目錄下的腳本是32位的,應該替換成支持windows版本的64位的,我這有編譯好的windows64位版本的hadoop包,如果缺少可以通過下面的鏈接下載.

這個應該是win7-64位版本的,但是我使用win10-64位機器也可以使用.

鏈接：https://pan.baidu.com/s/13Mf3m2fXt0TnXwgsiDejEg 密碼：pajo

還需要在idea中配置環境參數

HADOOP_HOME=E:\hadoop\hadoop-2.6.1
PATH=%PATH%;E:\hadoop\hadoop-2.6.1\bin

FIN

外網無法訪問hdfs文件系統