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.gora.query.impl; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import org.apache.commons.lang.builder.EqualsBuilder; import org.apache.commons.lang.builder.HashCodeBuilder; import org.apache.commons.lang.builder.ToStringBuilder; import org.apache.gora.filter.Filter; import org.apache.gora.persistency.impl.PersistentBase; import org.apache.gora.query.Query; import org.apache.gora.query.Result; import org.apache.gora.store.DataStore; import org.apache.gora.store.impl.DataStoreBase; import org.apache.gora.util.ClassLoadingUtils; import org.apache.gora.util.IOUtils; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configurable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.WritableUtils; import org.apache.hadoop.io.Writable; import org.apache.hadoop.util.ReflectionUtils; /** * Base class for Query implementations. */ public abstract class QueryBase<K, T extends PersistentBase> implements Query<K, T>, Writable, Configurable { protected DataStoreBase<K, T> dataStore; protected String queryString; protected String[] fields; protected K startKey; protected K endKey; protected long startTime = -1; protected long endTime = -1; protected Filter<K, T> filter; protected boolean localFilterEnabled = true; protected long limit = -1; private Configuration conf; public QueryBase(DataStore<K, T> dataStore) { this.dataStore = (DataStoreBase<K, T>) dataStore; } @Override public Result<K, T> execute() { return dataStore.execute(this); } @Override public void setDataStore(DataStore<K, T> dataStore) { this.dataStore = (DataStoreBase<K, T>) dataStore; } @Override public DataStore<K, T> getDataStore() { return dataStore; } @Override public void setFields(String... fields) { this.fields = fields; } @Override public String[] getFields() { return fields; } @Override public Filter<K, T> getFilter() { return filter; } @Override public void setFilter(Filter<K, T> filter) { this.filter = filter; } @Override public boolean isLocalFilterEnabled() { return localFilterEnabled; } @Override public void setLocalFilterEnabled(boolean enable) { this.localFilterEnabled = enable; } @Override public void setKey(K key) { setKeyRange(key, key); } @Override public void setStartKey(K startKey) { this.startKey = startKey; } @Override public void setEndKey(K endKey) { this.endKey = endKey; } @Override public void setKeyRange(K startKey, K endKey) { this.startKey = startKey; this.endKey = endKey; } @Override public K getKey() { if (startKey == endKey) { return startKey; //address comparison } return null; } @Override public K getStartKey() { return startKey; } @Override public K getEndKey() { return endKey; } @Override public void setTimestamp(long timestamp) { setTimeRange(timestamp, timestamp); } @Override public void setStartTime(long startTime) { this.startTime = startTime; } @Override public void setEndTime(long endTime) { this.endTime = endTime; } @Override public void setTimeRange(long startTime, long endTime) { this.startTime = startTime; this.endTime = endTime; } @Override public long getTimestamp() { return startTime == endTime ? startTime : -1; } @Override public long getStartTime() { return startTime; } @Override public long getEndTime() { return endTime; } @Override public void setLimit(long limit) { this.limit = limit; } @Override public long getLimit() { return limit; } public Configuration getConf() { return conf; } public void setConf(Configuration conf) { this.conf = conf; } @Override @SuppressWarnings("unchecked") public void readFields(DataInput in) throws IOException { String dataStoreClass = Text.readString(in); try { dataStore = (DataStoreBase<K, T>) ReflectionUtils .newInstance(ClassLoadingUtils.loadClass(dataStoreClass), conf); dataStore.readFields(in); } catch (ClassNotFoundException ex) { throw new IOException(ex); } boolean[] nullFields = IOUtils.readNullFieldsInfo(in); if (!nullFields[0]) queryString = Text.readString(in); if (!nullFields[1]) fields = IOUtils.readStringArray(in); if (!nullFields[2]) startKey = IOUtils.deserialize(getConf(), in, null, dataStore.getKeyClass()); if (!nullFields[3]) endKey = IOUtils.deserialize(getConf(), in, null, dataStore.getKeyClass()); if (!nullFields[4]) { String filterClass = Text.readString(in); try { filter = (Filter<K, T>) ReflectionUtils.newInstance(ClassLoadingUtils.loadClass(filterClass), conf); filter.readFields(in); } catch (ClassNotFoundException e) { throw new IOException(e); } } startTime = WritableUtils.readVLong(in); endTime = WritableUtils.readVLong(in); limit = WritableUtils.readVLong(in); localFilterEnabled = in.readBoolean(); } //@Override public void write(DataOutput out) throws IOException { //write datastore Text.writeString(out, dataStore.getClass().getCanonicalName()); dataStore.write(out); IOUtils.writeNullFieldsInfo(out, queryString, (fields), startKey, endKey, filter); if (queryString != null) Text.writeString(out, queryString); if (fields != null) IOUtils.writeStringArray(out, fields); if (startKey != null) IOUtils.serialize(getConf(), out, startKey, dataStore.getKeyClass()); if (endKey != null) IOUtils.serialize(getConf(), out, endKey, dataStore.getKeyClass()); if (filter != null) { Text.writeString(out, filter.getClass().getCanonicalName()); filter.write(out); } WritableUtils.writeVLong(out, getStartTime()); WritableUtils.writeVLong(out, getEndTime()); WritableUtils.writeVLong(out, getLimit()); out.writeBoolean(localFilterEnabled); } @SuppressWarnings({ "rawtypes" }) @Override public boolean equals(Object obj) { if (obj instanceof QueryBase) { QueryBase that = (QueryBase) obj; EqualsBuilder builder = new EqualsBuilder(); builder.append(dataStore, that.dataStore); builder.append(queryString, that.queryString); builder.append(fields, that.fields); builder.append(startKey, that.startKey); builder.append(endKey, that.endKey); builder.append(filter, that.filter); builder.append(limit, that.limit); builder.append(localFilterEnabled, that.localFilterEnabled); return builder.isEquals(); } return false; } @Override public int hashCode() { HashCodeBuilder builder = new HashCodeBuilder(); builder.append(dataStore); builder.append(queryString); builder.append(fields); builder.append(startKey); builder.append(endKey); builder.append(filter); builder.append(limit); builder.append(localFilterEnabled); return builder.toHashCode(); } @Override public String toString() { ToStringBuilder builder = new ToStringBuilder(this); builder.append("dataStore", dataStore); builder.append("fields", fields); builder.append("startKey", startKey); builder.append("endKey", endKey); builder.append("filter", filter); builder.append("limit", limit); builder.append("localFilterEnabled", localFilterEnabled); return builder.toString(); } }