java.net.ConnectException: 拒绝连接； For more details see: http://wiki.apache.org/hadoop/ConnectionRefu

遇到这种情况，先分析报错的代码在哪 ，什么情况所导致的，这是sqoop导入数据时，没有开启 Hadoop集群，所以报 “拒绝连接”，看到这几行代码，一定要检查自己的集群有没有开启

Warning: /opt/module/sqoop/bin/../../hcatalog does not exist! HCatalog jobs will fail.
Please set $HCAT_HOME to the root of your HCatalog installation.
Warning: /opt/module/sqoop/bin/../../accumulo does not exist! Accumulo imports will fail.
Please set $ACCUMULO_HOME to the root of your Accumulo installation.
2022-08-23 18:30:37,326 INFO sqoop.Sqoop: Running Sqoop version: 1.4.6
2022-08-23 18:30:37,345 WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
2022-08-23 18:30:37,420 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
2022-08-23 18:30:37,420 INFO tool.CodeGenTool: Beginning code generation
Tue Aug 23 18:30:37 CST 2022 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.
2022-08-23 18:30:37,805 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `staff` AS t LIMIT 1
2022-08-23 18:30:37,822 INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `staff` AS t LIMIT 1
2022-08-23 18:30:37,825 INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /opt/module/hadoop-3.1.3
注: /tmp/sqoop-ztx/compile/64be4fbe73894629df34ff5ea70ee000/staff.java使用或覆盖了已过时的 API。
注: 有关详细信息, 请使用 -Xlint:deprecation 重新编译。
2022-08-23 18:30:38,555 INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-ztx/compile/64be4fbe73894629df34ff5ea70ee000/staff.jar
2022-08-23 18:30:38,934 ERROR tool.ImportTool: Encountered IOException running import job: java.net.ConnectException: Call From hadoop102/192.168.10.102 to hadoop102:8020 failed on connection exception: java.net.ConnectException: 拒绝连接; 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$Invoker.invoke(ProtobufRpcEngine.java:118)
	at com.sun.proxy.$Proxy9.getFileInfo(Unknown Source)
	at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:904)
	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$Call.invokeOnce(RetryInvocationHandler.java:95)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:359)
	at com.sun.proxy.$Proxy10.getFileInfo(Unknown Source)
	at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:1661)
	at org.apache.hadoop.hdfs.DistributedFileSystem$29.doCall(DistributedFileSystem.java:1577)
	at org.apache.hadoop.hdfs.DistributedFileSystem$29.doCall(DistributedFileSystem.java:1574)
	at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
	at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1589)
	at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:1683)
	at org.apache.sqoop.tool.ImportTool.deleteTargetDir(ImportTool.java:529)
	at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:493)
	at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:605)
	at org.apache.sqoop.Sqoop.run(Sqoop.java:143)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
	at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:179)
	at org.apache.sqoop.Sqoop.runTool(Sqoop.java:218)
	at org.apache.sqoop.Sqoop.runTool(Sqoop.java:227)
	at org.apache.sqoop.Sqoop.main(Sqoop.java:236)
Caused by: java.net.ConnectException: 拒绝连接
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
	at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
	at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:531)
	at org.apache.hadoop.ipc.Client$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)
	... 30 more

开启自己的Hadoop集群，然后在导入数据

数据就导入成功了