UDF步骤：
1.继承org.apache.hadoop.hive.ql.exec.UDF
2.实现evaluate函数，evaluate函数支持重载
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package cn.sina.stat.hive.udf; import java.util.Arrays; import org.apache.hadoop.hive.ql.exec.UDF; public final class SortFieldContent extends UDF { public String evaluate( final String str, String delimiter) { if (str == null ) { return null ; } if (delimiter == null) { delimiter = "," ; } String[] strs = str.split(delimiter); Arrays. sort(strs); String result = "" ; for (int i = 0; i < strs. length; i++) { if (result.length() > 0) { result.concat(delimiter); } result.concat(strs[i]); } return result; } public String evaluate( final String str, String delimiter, String order) { if (str == null ) { return null ; } if (delimiter == null) { delimiter = "," ; } if (order != null && order.toUpperCase().equals( "ASC" )) { return evaluate(str, delimiter); } else { String[] strs = str.split(delimiter); Arrays. sort(strs); String result = "" ; for (int i = strs. length - 1; i >= 0; i--) { if (result.length() > 0) { result.concat(delimiter); } result.concat(strs[i]); } return result; } } }
UDAF步骤：
1.函数类继承org.apache.hadoop.hive.ql.exec.UDAF
内部类实现接口org.apache.hadoop.hive.ql.exec.UDAFEvaluator
2.Evaluator需要实现 init、iterate、terminatePartial、merge、terminate这几个函数
具体执行过程如图：
[java]
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package cn.sina.stat.hive.udaf; import java.util.Arrays; import org.apache.hadoop.hive.ql.exec.UDAF; import org.apache.hadoop.hive.ql.exec.UDAFEvaluator; public class ConcatClumnGroupByKeyWithOrder extends UDAF { public static class ConcatUDAFEvaluator implements UDAFEvaluator { public static class PartialResult { String result; String delimiter; String order; } private PartialResult partial; public void init() { partial = null; } public boolean iterate(String value, String delimiter, String order) { if (value == null) { return true; } if (partial == null) { partial = new PartialResult(); partial.result = new String(""); if (delimiter == null || delimiter.equals("")) { partial.delimiter = new String(","); } else { partial.delimiter = new String(delimiter); } if (order != null && (order.toUpperCase().equals("ASC") || order .toUpperCase().equals("DESC"))) { partial.order = new String(order); } else { partial.order = new String("ASC"); } } if (partial.result.length() > 0) { partial.result = partial.result.concat(partial.delimiter); } partial.result = partial.result.concat(value); return true; } public PartialResult terminatePartial() { return partial; } public boolean merge(PartialResult other) { if (other == null) { return true; } if (partial == null) { partial = new PartialResult(); partial.result = new String(other.result); partial.delimiter = new String(other.delimiter); partial.order = new String(other.order); } else { if (partial.result.length() > 0) { partial.result = partial.result.concat(partial.delimiter); } partial.result = partial.result.concat(other.result); } return true; } public String terminate() { String[] strs = partial.result.split(partial.delimiter); Arrays.sort(strs); String result = new String(""); if (partial.order.equals("DESC")) { for (int i = strs.length - 1; i >= 0; i--) { if (result.length() > 0) { result.concat(partial.delimiter); } result.concat(strs[i]); } } else { for (int i = 0; i < strs.length; i++) { if (result.length() > 0) { result.concat(partial.delimiter); } result.concat(strs[i]); } } return new String(result); } } }
UDTF步骤：
1.继承org.apache.hadoop.hive.ql.udf.generic.GenericUDTF
2.实现initialize, process, close三个方法
a.initialize初始化验证，返回字段名和字段类型
b.初始化完成后，调用process方法，对传入的参数进行处理，通过forword()方法把结果返回
c.最后调用close()方法进行清理工作
[java]
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package cn.sina.stat.hive.udtf; import java.util.ArrayList; import java.util.Arrays; import org.apache.hadoop.hive.ql.udf.generic.GenericUDTF; import org.apache.hadoop.hive.ql.exec.UDFArgumentException; import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException; import org.apache.hadoop.hive.ql.metadata.HiveException; import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector; import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory; import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector; import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory; public class SortFieldExplodeToPair extends GenericUDTF { @Override public void close() throws HiveException { } @Override public StructObjectInspector initialize(ObjectInspector[] args) throws UDFArgumentException { if (args.length != 3) { throw new UDFArgumentLengthException( "SortFieldExplodeToPair takes only three argument"); } if (args[0].getCategory() != ObjectInspector.Category.PRIMITIVE) { throw new UDFArgumentException( "SortFieldExplodeToPair takes string as first parameter"); } if (args[1].getCategory() != ObjectInspector.Category.PRIMITIVE) { throw new UDFArgumentException( "SortFieldExplodeToPair takes string as second parameter"); } if (args[2].getCategory() != ObjectInspector.Category.PRIMITIVE) { throw new UDFArgumentException( "SortFieldExplodeToPair takes string as third parameter"); } if (args[2] == null || !(args[2].toString().toUpperCase().equals("ASC") || args[2] .toString().toUpperCase().equals("DESC"))) { throw new UDFArgumentException( "SortFieldExplodeToPair third parameter must be \"ASC\" or \"DESC\""); } ArrayList<String> fieldNames = new ArrayList<String>(); ArrayList<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>(); fieldNames.add("col1"); fieldOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector); return ObjectInspectorFactory.getStandardStructObjectInspector( fieldNames, fieldOIs); } private final String[] forwardStr = new String[1]; @Override public void process(Object[] args) throws HiveException { String input = args[0].toString(); String delimiter = args[1].toString(); String order = args[2].toString(); String[] strList = input.split(delimiter); Arrays.sort(strList); if (strList.length > 1) { if (order.toUpperCase().equals("DESC")) { for (int i = strList.length - 1; i > 0; i--) { forwardStr[0] = strList[i].concat(delimiter).concat( strList[i - 1]); forward(forwardStr); } } else { for (int i = 0; i < strList.length - 1; i++) { forwardStr[0] = strList[i].concat(delimiter).concat( strList[i + 1]); forward(forwardStr); } } } else { forward(strList); } } }
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