Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.hive.hcatalog.data; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.sql.Date; import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Map.Entry; import org.apache.hadoop.hive.common.type.HiveChar; import org.apache.hadoop.hive.common.type.HiveDecimal; import org.apache.hadoop.hive.common.type.HiveVarchar; import org.apache.hadoop.hive.serde2.io.DateWritable; import org.apache.hadoop.hive.serde2.io.HiveCharWritable; import org.apache.hadoop.hive.serde2.io.HiveDecimalWritable; import org.apache.hadoop.hive.serde2.io.HiveVarcharWritable; import org.apache.hadoop.hive.serde2.io.TimestampWritable; import org.apache.hadoop.io.VIntWritable; import org.apache.hadoop.io.VLongWritable; /* * when adding support for new types, we should try to use classes of Hive value system to keep * things more readable (though functionally it should not make a difference). */ public abstract class ReaderWriter { private static final String UTF8 = "UTF-8"; public static Object readDatum(DataInput in) throws IOException { byte type = in.readByte(); switch (type) { case DataType.STRING: byte[] buffer = new byte[in.readInt()]; in.readFully(buffer); return new String(buffer, UTF8); case DataType.INTEGER: VIntWritable vint = new VIntWritable(); vint.readFields(in); return vint.get(); case DataType.LONG: VLongWritable vlong = new VLongWritable(); vlong.readFields(in); return vlong.get(); case DataType.FLOAT: return in.readFloat(); case DataType.DOUBLE: return in.readDouble(); case DataType.BOOLEAN: return in.readBoolean(); case DataType.BYTE: return in.readByte(); case DataType.SHORT: return in.readShort(); case DataType.NULL: return null; case DataType.BINARY: int len = in.readInt(); byte[] ba = new byte[len]; in.readFully(ba); return ba; case DataType.MAP: int size = in.readInt(); Map<Object, Object> m = new HashMap<Object, Object>(size); for (int i = 0; i < size; i++) { m.put(readDatum(in), readDatum(in)); } return m; case DataType.LIST: int sz = in.readInt(); List<Object> list = new ArrayList<Object>(sz); for (int i = 0; i < sz; i++) { list.add(readDatum(in)); } return list; case DataType.CHAR: HiveCharWritable hcw = new HiveCharWritable(); hcw.readFields(in); return hcw.getHiveChar(); case DataType.VARCHAR: HiveVarcharWritable hvw = new HiveVarcharWritable(); hvw.readFields(in); return hvw.getHiveVarchar(); case DataType.DECIMAL: HiveDecimalWritable hdw = new HiveDecimalWritable(); hdw.readFields(in); return hdw.getHiveDecimal(); case DataType.DATE: DateWritable dw = new DateWritable(); dw.readFields(in); return dw.get(); case DataType.TIMESTAMP: TimestampWritable tw = new TimestampWritable(); tw.readFields(in); return tw.getTimestamp(); default: throw new IOException("Unexpected data type " + type + " found in stream."); } } public static void writeDatum(DataOutput out, Object val) throws IOException { // write the data type byte type = DataType.findType(val); out.write(type); switch (type) { case DataType.LIST: List<?> list = (List<?>) val; int sz = list.size(); out.writeInt(sz); for (int i = 0; i < sz; i++) { writeDatum(out, list.get(i)); } return; case DataType.MAP: Map<?, ?> m = (Map<?, ?>) val; out.writeInt(m.size()); Iterator<?> i = m.entrySet().iterator(); while (i.hasNext()) { Entry<?, ?> entry = (Entry<?, ?>) i.next(); writeDatum(out, entry.getKey()); writeDatum(out, entry.getValue()); } return; case DataType.INTEGER: new VIntWritable((Integer) val).write(out); return; case DataType.LONG: new VLongWritable((Long) val).write(out); return; case DataType.FLOAT: out.writeFloat((Float) val); return; case DataType.DOUBLE: out.writeDouble((Double) val); return; case DataType.BOOLEAN: out.writeBoolean((Boolean) val); return; case DataType.BYTE: out.writeByte((Byte) val); return; case DataType.SHORT: out.writeShort((Short) val); return; case DataType.STRING: String s = (String) val; byte[] utfBytes = s.getBytes(ReaderWriter.UTF8); out.writeInt(utfBytes.length); out.write(utfBytes); return; case DataType.BINARY: byte[] ba = (byte[]) val; out.writeInt(ba.length); out.write(ba); return; case DataType.NULL: //for NULL we just write out the type return; case DataType.CHAR: new HiveCharWritable((HiveChar) val).write(out); return; case DataType.VARCHAR: new HiveVarcharWritable((HiveVarchar) val).write(out); return; case DataType.DECIMAL: new HiveDecimalWritable((HiveDecimal) val).write(out); return; case DataType.DATE: new DateWritable((Date) val).write(out); return; case DataType.TIMESTAMP: new TimestampWritable((java.sql.Timestamp) val).write(out); return; default: throw new IOException("Unexpected data type " + type + " found in stream."); } } }