问题描述
(1) windows电脑向aliyun进行hdfs api文件追加操作时出现下方错误：

DEBUG [Thread-3] (DFSOutputStream.java:1503) - Connecting to datanode *.*.*.*:9866
DEBUG [IPC Client (927327686) connection to centos8/*.*.*.*:9820 from root] (Client.java:1192) - IPC Client (927327686) connection to centos8/*.*.*.*:9820 from root: closed
DEBUG [IPC Client (927327686) connection to centos8/*.*.*.*:9820 from root] (Client.java:987) - IPC Client (927327686) connection to centos8/*.*.*.*:9820 from root: stopped, remaining connections 0INFO [Thread-3] (DFSOutputStream.java:1343) - Exception in createBlockOutputStream
java.net.ConnectException: Connection timed out: no further informationat 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.hdfs.DFSOutputStream.createSocketForPipeline(DFSOutputStream.java:1508)at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.createBlockOutputStream(DFSOutputStream.java:1284)at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1237)at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:449)

(2) windows电脑向aliyun进行mapreduce api操作时出现下方错误：

 WARN [LocalJobRunner Map Task Executor #0] (BlockReaderFactory.java:716) - I/O error constructing remote block reader.

问题原因
客户端创建文件先访问NameNode服务器进行创建文件Meta信息，以及文件树，此时访问NameNode的IP，NameNode服务器创建文件成功后，会返回对应dataNode的服务器节点，但此时的节点信息中的ip是与NameNode在同一网络下的内网IP，客户端是无法访问，也就无法写入。

问题解决
(1) 在hdfs-site.xml中添加配置

	<property><name>dfs.client.use.datanode.hostname</name><value>true</value></property>

(2) 或者在idea代码中添加

configuration.set("dfs.client.use.datanode.hostname", "true");