IntelliJ IDEA将代码打成Jar包的方式,注意，一定要确保打包Jar的时候日志输出是准确的，没有报错才行，而不是单纯看到有Jar包生成了就觉得包打好了，如果你不看打包报错日志，单纯去copy走生成的错误的包，后面hive引用该包还是会报错，你还的改然后重新打包，然后将该包上传到hdfs上，如我把它上传到hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar；
  万事具备，现在开始打开hive的客户端，创建永久的UDF函数，Hive Cli环境下操作如下； hive> create function rowyet.picratio as 'org.example.PicRatio_UDF' using jar 'hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar'; Added [/opt/hive/log/c0017eab-0d8b-49bd-8157-09237071085c_resources/udf-1.0-SNAPSHOT-jar-with-dependencies.jar] to class path Added resources: [hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar] OK Time taken: 6.03 seconds --测试 hive> select rowyet.picratio("4:3") > ; OK 4:3 Time taken: 0.902 seconds, Fetched: 1 row(s) hive> select rowyet.picratio("3:4"); OK 4:3 Time taken: 0.064 seconds, Fetched: 1 row(s)也可以临时性添加函数，具体HiveQL如下,一般不常用，都是建立永久的居多；create temporary function rowyet.picratio as 'org.example.PicRatio_UDF' using jar 'hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar';

异常分析

  1. 如果连加载Jar都报错,未出现以下加载Jar的日志的语句就报错了； 如报错FAILED: SemanticException java.lang.IllegalArgumentException: java.net.UnknownHostException: hive，说明hive客户端内没有加载到Jar包，请检查你的Jar路径对不对，是否多了少了/；
Added [/opt/hive/log/c0017eab-0d8b-49bd-8157-09237071085c_resources/udf-1.0-SNAPSHOT-jar-with-dependencies.jar] to class path
Added resources: [hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar]
OK
  1. 如果加载Jar显示有日志，而是报错Failed to register rowyet.picratio using class com.ruoyin.hiveudf.PicRatio_UDF这种类似的，说明是Jar打包的有问题，Jar内存在问题，请回去看打包日志，是否存在错误，修复掉即可。

删除自定义UDF函数

也支持删除自定义得UDF,具体HiveQL如下；

hive> drop function rowyet.picratio;
Added [/opt/hive/log/ce6a5159-2063-4796-b4cb-5a6762b0ad15_resources/udf-1.0-SNAPSHOT-jar-with-dependencies.jar] to class path
Added resources: [hdfs:///hive/hive_udf_jar/udf-1.0-SNAPSHOT-jar-with-dependencies.jar]
OK
Time taken: 0.752 seconds
hive> select rowyet.picratio("4:3")
    > ;
FAILED: SemanticException [Error 10011]: Invalid function rowyet.picratio