Java tutorial
// // typica - A client library for Amazon Web Services // Copyright (C) 2007 Xerox Corporation // // 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. // package com.xerox.amazonws.sdb; import java.io.InputStream; import java.io.IOException; import java.util.ArrayList; import java.util.HashMap; import java.util.Hashtable; import java.util.List; import java.util.Map; import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.RejectedExecutionHandler; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import javax.xml.bind.JAXBException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient.HttpException; import org.apache.commons.httpclient.methods.GetMethod; import com.xerox.amazonws.common.AWSQueryConnection; import com.xerox.amazonws.typica.sdb.jaxb.QueryResponse; /** * This class provides an interface with the Amazon SDB service. It provides methods for * listing and deleting items. * * @author D. Kavanagh * @author developer@dotech.com */ public class Domain extends AWSQueryConnection { private static Log logger = LogFactory.getLog(Domain.class); private String domainName; private int maxThreads = 30; private ThreadPoolExecutor executor; protected Domain(String domainName, String awsAccessId, String awsSecretKey, boolean isSecure, String server) throws SDBException { super(awsAccessId, awsSecretKey, isSecure, server, isSecure ? 443 : 80); this.domainName = domainName; SimpleDB.setVersionHeader(this); } /** * Gets the name of the domain represented by this object. * * @return the name of the domain */ public String getName() { return domainName; } /** * Gets the max number of threads to use for the threaded operations. * * @return max number of threads being used */ public int getMaxThreads() { return maxThreads; } /** * Sets the max number of threads to use for the threaded operations. * * @param threads the new max to set */ public void setMaxThreads(int threads) { maxThreads = threads; } /** * Method for getting an Item object without getting a list of them. * * @param identifier id of the item * @return the object representing the item * @throws SDBException wraps checked exceptions */ public Item getItem(String identifier) throws SDBException { Item ret = new Item(identifier, domainName, getAwsAccessKeyId(), getSecretAccessKey(), isSecure(), getServer()); ret.setSignatureVersion(getSignatureVersion()); ret.setHttpClient(getHttpClient()); return ret; } /** * Gets a list of all items in this domain * * @return the object containing the items, a more token, etc. * @throws SDBException wraps checked exceptions */ public QueryResult listItems() throws SDBException { return listItems(null); } /** * Gets a list of items in this domain filtered by the query string. * * @param queryString the filter statement * @return the object containing the items, a more token, etc. * @throws SDBException wraps checked exceptions */ public QueryResult listItems(String queryString) throws SDBException { return listItems(queryString, null); } /** * Gets a list of items in this domain filtered by the query string. * * @param queryString the filter statement * @param nextToken the token used to return more items in the query result set * @return the object containing the items, a more token, etc. * @throws SDBException wraps checked exceptions */ public QueryResult listItems(String queryString, String nextToken) throws SDBException { return listItems(queryString, null, 0); } /** * Gets a list of items in this domain filtered by the query string. * * @param queryString the filter statement * @param nextToken the token used to return more items in the query result set * @param maxResults a limit to the number of results to return now * @return the object containing the items, a more token, etc. * @throws SDBException wraps checked exceptions */ public QueryResult listItems(String queryString, String nextToken, int maxResults) throws SDBException { Map<String, String> params = new HashMap<String, String>(); params.put("DomainName", domainName); params.put("QueryExpression", (queryString == null) ? "" : queryString); if (nextToken != null) { params.put("NextToken", nextToken); } if (maxResults > 0) { params.put("MaxNumberOfItems", "" + maxResults); } GetMethod method = new GetMethod(); try { QueryResponse response = makeRequest(method, "Query", params, QueryResponse.class); return new QueryResult(response.getQueryResult().getNextToken(), Item.createList(response.getQueryResult().getItemNames().toArray(new String[] {}), domainName, getAwsAccessKeyId(), getSecretAccessKey(), isSecure(), getServer(), getSignatureVersion(), getHttpClient())); } catch (JAXBException ex) { throw new SDBException("Problem parsing returned message.", ex); } catch (HttpException ex) { throw new SDBException(ex.getMessage(), ex); } catch (IOException ex) { throw new SDBException(ex.getMessage(), ex); } finally { method.releaseConnection(); } } /** * Gets attributes of given items. This method threads off the get requests and * aggregates the responses. * * @param items the list of items to get attributes for * @return the map of items with lists of attributes * @throws SDBException wraps checked exceptions */ public Map<String, List<ItemAttribute>> getItemsAttributes(List<String> items) throws SDBException { Map<String, List<ItemAttribute>> results = new Hashtable<String, List<ItemAttribute>>(); ThreadPoolExecutor pool = getThreadPoolExecutor(); pool.setRejectedExecutionHandler(new RejectionHandler()); Counter running = new Counter(0); for (String item : items) { while (pool.getActiveCount() == pool.getMaximumPoolSize()) { try { Thread.sleep(100); } catch (InterruptedException ex) { } } synchronized (running) { running.increment(); } pool.execute(new AttrWorker(getItem(item), running, results, null)); Thread.yield(); } while (true) { if (running.getValue() == 0) { break; } try { Thread.sleep(500); } catch (InterruptedException ex) { } } if (this.executor == null) { pool.shutdown(); } return results; } /** * Gets attributes of given items. This method threads off the get requests and * aggregates the responses. * * @param items the list of items to get attributes for * @param listener class that will be notified when items are ready * @throws SDBException wraps checked exceptions */ public void getItemsAttributes(List<String> items, ItemListener listener) throws SDBException { ThreadPoolExecutor pool = getThreadPoolExecutor(); pool.setRejectedExecutionHandler(new RejectionHandler()); Counter running = new Counter(0); for (String item : items) { while (pool.getActiveCount() == pool.getMaximumPoolSize()) { try { Thread.sleep(100); } catch (InterruptedException ex) { } } synchronized (running) { running.increment(); } pool.execute(new AttrWorker(getItem(item), running, null, listener)); Thread.yield(); } while (true) { if (running.getValue() == 0) { break; } try { Thread.sleep(500); } catch (InterruptedException ex) { } } if (this.executor == null) { pool.shutdown(); } } /** * Gets attributes of items specified in the query string. This method threads off the * get requests and aggregates the responses. * * @param queryString the filter statement * @param listener class that will be notified when items are ready * @throws SDBException wraps checked exceptions */ public void listItemsAttributes(String queryString, ItemListener listener) throws SDBException { ThreadPoolExecutor pool = getThreadPoolExecutor(); pool.setRejectedExecutionHandler(new RejectionHandler()); String nextToken = ""; Counter running = new Counter(0); do { try { QueryResult result = listItems(queryString, nextToken, 250); List<Item> items = result.getItemList(); for (Item i : items) { while (pool.getActiveCount() == pool.getMaximumPoolSize()) { try { Thread.sleep(100); } catch (InterruptedException ex) { } } synchronized (running) { running.increment(); } pool.execute(new AttrWorker(i, running, null, listener)); Thread.yield(); } nextToken = result.getNextToken(); } catch (SDBException ex) { System.out.println("Query '" + queryString + "' Failure: "); ex.printStackTrace(); } } while (nextToken != null && nextToken.trim().length() > 0); while (true) { if (running.getValue() == 0) { break; } try { Thread.sleep(500); } catch (InterruptedException ex) { } } if (this.executor == null) { pool.shutdown(); } } /** * Deletes an item. * * @param identifier the name of the item to be deleted * @throws SDBException wraps checked exceptions */ public void deleteItem(String identifier) throws SDBException { getItem(identifier).deleteAttributes(null); } static List<Domain> createList(String[] domainNames, String awsAccessKeyId, String awsSecretAccessKey, boolean isSecure, String server, int signatureVersion, HttpClient hc) throws SDBException { ArrayList<Domain> ret = new ArrayList<Domain>(); for (int i = 0; i < domainNames.length; i++) { Domain dom = new Domain(domainNames[i], awsAccessKeyId, awsSecretAccessKey, isSecure, server); dom.setSignatureVersion(signatureVersion); dom.setHttpClient(hc); ret.add(dom); } return ret; } public ThreadPoolExecutor getThreadPoolExecutor() { if (executor != null) { return executor; } else { return new ThreadPoolExecutor(maxThreads, maxThreads, 5, TimeUnit.SECONDS, new ArrayBlockingQueue(maxThreads)); } } public void setThreadPoolExecutor(ThreadPoolExecutor executor) { this.executor = executor; } protected class RejectionHandler implements RejectedExecutionHandler { public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) { // ok, on the rare occasion, just run it here! r.run(); } } }