3.3. UDF 开发实例 3.3.1. Step 1 创建 Maven 工程 <dependencies> <!-- https://mvnrepository.com/artifact/org.apache.hive/hive-exec --> <dependency> <groupId>org.apache.hive</groupId> <artifactId>hive-exec</artifactId> <version>3.1.1</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.hadoop/hadoop-common --> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>3.1.1</version> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.0</version> <configuration> <source>1.8</source> <target>1.8</target> <encoding>UTF-8</encoding> </configuration> </plugin> </plugins> </build> 3.3.2. Step 2 开发 Java 类集成 UDF public class MyUDF extends UDF { public Text evaluate(final Text str) { String tmp_str = str.toString(); if (str != null && !tmp_str.equals("")) { String str_ret = tmp_str.substring(0, 1).toUpperCase() + tmp_str.substring(1); return new Text(str_ret); } return new Text(""); }} 3.3.3. Step 3 项目打包，并上传到hive的lib目录下
3.3.4. Step 4 添加jar包
重命名我们的jar包名称
cd /export/servers/apache-hive-3.1.1-kwdfn/lib mv original-day_05_hive_udf-1.0-SNAPSHOT.jar myudf.jar
hive的客户端添加我们的jar包
add jar /export/servers/apache-hive-3.1.1-kwdfn/lib/udf.jar; 3.3.5. Step 5 设置函数与我们的自定义函数关联 create temporary function my_upper as 'cn.itcast.udf.ItcastUDF';
3.3.6. Step 6 使用自定义函数 select my_upper('abc');