sparkSQL中自定义函数——UDF

自定义函数是可以根据函数中参数的个数去选择哪一种函数（UDF1,UDF2...） 

SparkConf conf = new SparkConf();
conf.setMaster("local");
conf.setAppName("udf");
JavaSparkContext sc = new JavaSparkContext(conf);
SQLContext sqlContext = new SQLContext(sc);
JavaRDD parallelize = sc.parallelize(Arrays.asList("zhansan","lisi","wangwu"));
JavaRDD rowRDD = parallelize.map(new Function() {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Override
	public Row call(String s) throws Exception {
return RowFactory.create(s);
	}
});

List fields = new ArrayList();
fields.add(DataTypes.createStructField("name", DataTypes.StringType,true));

StructType schema = DataTypes.createStructType(fields);
DataFrame df = sqlContext.createDataFrame(rowRDD,schema);
df.registerTempTable("user");

/**
 * 根据UDF函数参数的个数来决定是实现哪一个UDF  UDF1，UDF2。。。。UDF1xxx
 */
sqlContext.udf().register("StrLen", new UDF1() {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Override
	public Integer call(String t1) throws Exception {
             return t1.length();
	}
}, DataTypes.IntegerType);
sqlContext.sql("select name ,StrLen(name) as length from user").show();

//sqlContext.udf().register("StrLen",new UDF2() {
//
//	/**
//	 * 
//	 */
//	private static final long serialVersionUID = 1L;
//
//	@Override
//	public Integer call(String t1, Integer t2) throws Exception {
//return t1.length()+t2;
//	}
//} ,DataTypes.IntegerType );
//sqlContext.sql("select name ,StrLen(name,10) as length from user").show();

sc.stop();	

可以根据UDF函数中参数的个数来决定是实现哪一个UDF：

Scala代码：

val conf = new SparkConf()
conf.setMaster("local").setAppName("udf")
val sc = new SparkContext(conf)
val sqlContext = new SQLContext(sc);
val rdd = sc.makeRDD(Array("zhansan","lisi","wangwu"))
val rowRDD = rdd.map { x => {
  RowFactory.create(x)
} }
val schema = DataTypes.createStructType(Array(StructField("name",StringType,true)))
val df = sqlContext.createDataFrame(rowRDD, schema)
df.registerTempTable("user")
//sqlContext.udf.register("StrLen",(s : String)=>{s.length()})
//sqlContext.sql("select name ,StrLen(name) as length from user").show
sqlContext.udf.register("StrLen",(s : String,i:Int)=>{s.length()+i})
sqlContext.sql("select name ,StrLen(name,10) as length from user").show
sc.stop()