这篇文章主要为大家展示了“hive3.0.0如何自定义函数”，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下“hive3.0.0如何自定义函数”这篇文章吧。
示例代码
package hello_hive;import org.apache.hadoop.hive.ql.exec.UDFArgumentException;import org.apache.hadoop.hive.ql.metadata.HiveException;import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;import org.apache.hadoop.io.Text;import org.apache.hive.hplsql.Udf;public class HiveTest extends Udf{StringBuilder builder = new StringBuilder();public String evaluate(String invalue) throws HiveException {int length = invalue.length();char[] cha = invalue.toCharArray();for(int i = 0 ;i<length;i++) {String tmp = String.valueOf(cha[i]);if(Math.floorMod(i, 2)==0) {builder.append(tmp.toUpperCase());}else {builder.append(tmp.toLowerCase());}}return builder.toString();}}class HiveTest2 extends GenericUDF{StringBuilder builder = new StringBuilder();Text tx = new Text();@Override//主要逻辑函数public Object evaluate(DeferredObject[] defer) throws HiveException {builder.delete(0, builder.length());if(defer.length<=0) {return null;}else {int length = defer[0].get().toString().length();char[] cha = defer[0].get().toString().toCharArray();for(int i = 0 ;i<length;i++) {String tmp = String.valueOf(cha[i]);if(Math.floorMod(i, 2)==0) {builder.append(tmp.toUpperCase());}else {builder.append(tmp.toLowerCase());}}}tx.set(builder.toString());return tx;}//获取函数帮助信息的函数@Overridepublic String getDisplayString(String[] args) {return getStandardDisplayString("Usage: upd(strs)", args);}//判断函数返回值类型的函数@Overridepublic ObjectInspector initialize(ObjectInspector[] arg0) throws UDFArgumentException {ObjectInspector outputOI =PrimitiveObjectInspectorFactory.writableStringObjectInspector;return outputOI;}}以上是“hive3.0.0如何自定义函数”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注编程网行业资讯频道！
