quickstart.Querying Maven / Gradle / Ivy

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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * Licensed 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. See accompanying
 * LICENSE file.
 */
package quickstart;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Collection;
import com.gemstone.gemfire.cache.Cache;
import com.gemstone.gemfire.cache.CacheFactory;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.cache.query.Query;
import com.gemstone.gemfire.cache.query.QueryService;
import com.gemstone.gemfire.cache.query.SelectResults;

/**
 * You can query on the data in your cached regions. Please refer to the 
 * quickstart guide for instructions on how to run this example. 
 * 
 * 
 * @author GemStone Systems, Inc.
 * @since 4.1.1
 */
public class Querying {

  public static void main(String[] args) throws Exception {
    System.out.println("\nThis example demonstrates querying on a set of data in a GemFire ");
    System.out.println("region. The data represents Portfolios containing Positions. ");

    System.out.println("\nConnecting to the distributed system and creating the cache.");
    
    // Create the cache which causes the cache-xml-file to be parsed
    Cache cache = new CacheFactory()
        .set("name", "Querying")
        .set("cache-xml-file", "xml/Querying.xml")
        .create();

    // Get the exampleRegion
    Region exampleRegion = cache.getRegion("exampleRegion");
    System.out.println("Example region, " + exampleRegion.getFullPath() + ", created in cache. ");

    // Get the query service for the cache
    QueryService queryService = cache.getQueryService();
    Query query = null;
    Object result = null;
    
    // Query everything to show what's in the region
    query = queryService.newQuery("SELECT DISTINCT * FROM /exampleRegion");
    System.out.println("\nExecuting query:\n\t" + query.getQueryString()); 
    result = query.execute();
    System.out.println("Query result:\n\t" + formatQueryResult(result));
    
    System.out.println("\nPress Enter to continue to next query...");
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    bufferedReader.readLine();
    
    // Execute a simple query on the exampleRegion 
    query = queryService.newQuery("/exampleRegion.isDestroyed");
    System.out.println("\nExecuting query:\n\t" + query.getQueryString()); 
    result = query.execute();
    System.out.println("Query result:\n\t" + formatQueryResult(result));
    
    System.out.println("\nPress Enter to continue to next query...");
    // bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    bufferedReader.readLine();
    
    // Execute a query with SELECT, FROM and WHERE clauses
    query = queryService.newQuery(
        "SELECT DISTINCT * FROM /exampleRegion WHERE status = 'active'");
    System.out.println("Executing query:\n\t" + query.getQueryString()); 
    result = query.execute();
    System.out.println("Query result:\n\t" + formatQueryResult(result));
    
    System.out.println("Press Enter to continue to next query...");
    bufferedReader.readLine();
    
    // Execute a query with a compound WHERE clause 
    query = queryService.newQuery(
        "SELECT DISTINCT * FROM /exampleRegion " +
        "WHERE status = 'active' AND \"type\" = 'type3'");
    System.out.println("Executing query:\n\t" + query.getQueryString()); 
    result = query.execute();
    System.out.println("Query result:\n\t" + formatQueryResult(result));

    System.out.println("Press Enter to continue to next query...");
    bufferedReader.readLine();
    
    // Execute a more complex query
    query = queryService.newQuery(
        "IMPORT quickstart.Position; " +
        "SELECT DISTINCT posnVal " +
        "FROM /exampleRegion, positions.values posnVal TYPE Position " +
        "WHERE status = 'active' AND posnVal.mktValue >= 25.00");
    System.out.println("Executing query:\n\t" + query.getQueryString()); 
    result = query.execute();
    System.out.println("Query result:\n\t" + formatQueryResult(result));

    // Close the cache and disconnect from GemFire distributed system
    System.out.println("Closing the cache and disconnecting.");
    cache.close();
  }
  
  public static String formatQueryResult(Object result) {
    if (result == null) {
      return "null";
    }
    else if (result == QueryService.UNDEFINED) {
      return "UNDEFINED";
    }
    if (result instanceof SelectResults) {
      Collection collection = ((SelectResults)result).asList();
      StringBuffer sb = new StringBuffer();
      for (Object e: collection) {
        sb.append(e + "\n\t");
      }
      return sb.toString();
    }
    else {
      return result.toString();
    }
  }
}