mirror of https://github.com/tasks/tasks
Got amazon search working
Tim Su
13 years ago
parent
6546170ba1
commit
be714da510
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/**********************************************************************************************
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* Copyright 2009 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file
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* except in compliance with the License. A copy of the License is located at
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*
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* http://aws.amazon.com/apache2.0/
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*
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* or in the "LICENSE.txt" file accompanying this file. This file is distributed on an "AS IS"
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* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations under the License.
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*
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* ********************************************************************************************
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*
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* Amazon Product Advertising API
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* Signed Requests Sample Code
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*
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* API Version: 2009-03-31
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*
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*/
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package com.todoroo.astrid.helper;
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import java.io.UnsupportedEncodingException;
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import java.net.URLDecoder;
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import java.net.URLEncoder;
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import java.security.InvalidKeyException;
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import java.security.NoSuchAlgorithmException;
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import java.text.DateFormat;
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import java.text.SimpleDateFormat;
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import java.util.Calendar;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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import java.util.SortedMap;
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import java.util.TimeZone;
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import java.util.TreeMap;
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import javax.crypto.Mac;
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import javax.crypto.spec.SecretKeySpec;
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import org.apache.commons.codec.binary.Base64;
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/**
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* This class contains all the logic for signing requests
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* to the Amazon Product Advertising API.
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*/
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@SuppressWarnings("nls")
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public class AmazonRequestsHelper {
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/**
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* All strings are handled as UTF-8
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*/
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private static final String UTF8_CHARSET = "UTF-8";
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/**
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* The HMAC algorithm required by Amazon
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*/
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private static final String HMAC_SHA256_ALGORITHM = "HmacSHA256";
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/**
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* This is the URI for the service, don't change unless you really know
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* what you're doing.
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*/
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private static final String REQUEST_URI = "/onca/xml";
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/**
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* The sample uses HTTP GET to fetch the response. If you changed the sample
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* to use HTTP POST instead, change the value below to POST.
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*/
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private static final String REQUEST_METHOD = "GET";
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private String endpoint = null;
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private String awsAccessKeyId = null;
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private String awsSecretKey = null;
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private SecretKeySpec secretKeySpec = null;
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private Mac mac = null;
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/**
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* You must provide the three values below to initialize the helper.
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*
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* @param endpoint Destination for the requests.
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* @param awsAccessKeyId Your AWS Access Key ID
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* @param awsSecretKey Your AWS Secret Key
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*/
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public static AmazonRequestsHelper getInstance(
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String endpoint,
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String awsAccessKeyId,
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String awsSecretKey
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) throws IllegalArgumentException, UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException
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{
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if (null == endpoint || endpoint.length() == 0)
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{ throw new IllegalArgumentException("endpoint is null or empty"); }
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if (null == awsAccessKeyId || awsAccessKeyId.length() == 0)
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{ throw new IllegalArgumentException("awsAccessKeyId is null or empty"); }
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if (null == awsSecretKey || awsSecretKey.length() == 0)
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{ throw new IllegalArgumentException("awsSecretKey is null or empty"); }
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AmazonRequestsHelper instance = new AmazonRequestsHelper();
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instance.endpoint = endpoint.toLowerCase();
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instance.awsAccessKeyId = awsAccessKeyId;
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instance.awsSecretKey = awsSecretKey;
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byte[] secretyKeyBytes = instance.awsSecretKey.getBytes(UTF8_CHARSET);
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instance.secretKeySpec = new SecretKeySpec(secretyKeyBytes, HMAC_SHA256_ALGORITHM);
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instance.mac = Mac.getInstance(HMAC_SHA256_ALGORITHM);
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instance.mac.init(instance.secretKeySpec);
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return instance;
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}
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/**
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* The construct is private since we'd rather use getInstance()
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*/
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private AmazonRequestsHelper() {
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//
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}
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/**
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* This method signs requests in hashmap form. It returns a URL that should
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* be used to fetch the response. The URL returned should not be modified in
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* any way, doing so will invalidate the signature and Amazon will reject
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* the request.
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*/
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public String sign(Map<String, String> params) {
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// Let's add the AWSAccessKeyId and Timestamp parameters to the request.
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params.put("AWSAccessKeyId", this.awsAccessKeyId);
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params.put("Timestamp", this.timestamp());
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// The parameters need to be processed in lexicographical order, so we'll
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// use a TreeMap implementation for that.
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SortedMap<String, String> sortedParamMap = new TreeMap<String, String>(params);
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// get the canonical form the query string
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String canonicalQS = this.canonicalize(sortedParamMap);
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// create the string upon which the signature is calculated
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String toSign =
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REQUEST_METHOD + "\n"
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+ this.endpoint + "\n"
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+ REQUEST_URI + "\n"
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+ canonicalQS;
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// get the signature
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String hmac = this.hmac(toSign);
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String sig = this.percentEncodeRfc3986(hmac);
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// construct the URL
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String url =
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"http://" + this.endpoint + REQUEST_URI + "?" + canonicalQS + "&Signature=" + sig;
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return url;
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}
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/**
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* This method signs requests in query-string form. It returns a URL that
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* should be used to fetch the response. The URL returned should not be
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* modified in any way, doing so will invalidate the signature and Amazon
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* will reject the request.
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*/
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public String sign(String queryString) {
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// let's break the query string into it's constituent name-value pairs
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Map<String, String> params = this.createParameterMap(queryString);
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// then we can sign the request as before
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return this.sign(params);
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}
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/**
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* Compute the HMAC.
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*
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* @param stringToSign String to compute the HMAC over.
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* @return base64-encoded hmac value.
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*/
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private String hmac(String stringToSign) {
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String signature = null;
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byte[] data;
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byte[] rawHmac;
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try {
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data = stringToSign.getBytes(UTF8_CHARSET);
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rawHmac = mac.doFinal(data);
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Base64 encoder = new Base64();
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signature = new String(encoder.encode(rawHmac));
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} catch (UnsupportedEncodingException e) {
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throw new RuntimeException(UTF8_CHARSET + " is unsupported!", e);
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}
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return signature;
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}
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/**
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* Generate a ISO-8601 format timestamp as required by Amazon.
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*
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* @return ISO-8601 format timestamp.
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*/
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private String timestamp() {
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String timestamp = null;
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Calendar cal = Calendar.getInstance();
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DateFormat dfm = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
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dfm.setTimeZone(TimeZone.getTimeZone("GMT"));
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timestamp = dfm.format(cal.getTime());
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return timestamp;
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}
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/**
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* Canonicalize the query string as required by Amazon.
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*
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* @param sortedParamMap Parameter name-value pairs in lexicographical order.
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* @return Canonical form of query string.
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*/
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private String canonicalize(SortedMap<String, String> sortedParamMap) {
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if (sortedParamMap.isEmpty()) {
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return "";
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}
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StringBuffer buffer = new StringBuffer();
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Iterator<Map.Entry<String, String>> iter = sortedParamMap.entrySet().iterator();
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while (iter.hasNext()) {
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Map.Entry<String, String> kvpair = iter.next();
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buffer.append(percentEncodeRfc3986(kvpair.getKey()));
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buffer.append("=");
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buffer.append(percentEncodeRfc3986(kvpair.getValue()));
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if (iter.hasNext()) {
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buffer.append("&");
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}
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}
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String cannoical = buffer.toString();
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return cannoical;
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}
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/**
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* Percent-encode values according the RFC 3986. The built-in Java
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* URLEncoder does not encode according to the RFC, so we make the
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* extra replacements.
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*
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* @param s decoded string
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* @return encoded string per RFC 3986
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*/
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private String percentEncodeRfc3986(String s) {
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String out;
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try {
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out = URLEncoder.encode(s, UTF8_CHARSET)
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.replace("+", "%20")
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.replace("*", "%2A")
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.replace("%7E", "~");
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} catch (UnsupportedEncodingException e) {
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out = s;
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}
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return out;
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}
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/**
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* Takes a query string, separates the constituent name-value pairs
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* and stores them in a hashmap.
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*
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* @param queryString
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* @return
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*/
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private Map<String, String> createParameterMap(String queryString) {
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Map<String, String> map = new HashMap<String, String>();
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String[] pairs = queryString.split("&");
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for (String pair: pairs) {
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if (pair.length() < 1) {
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continue;
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}
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String[] tokens = pair.split("=",2);
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for(int j=0; j<tokens.length; j++)
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{
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try {
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tokens[j] = URLDecoder.decode(tokens[j], UTF8_CHARSET);
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} catch (UnsupportedEncodingException e) {
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// unpossible
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}
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}
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switch (tokens.length) {
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case 1: {
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if (pair.charAt(0) == '=') {
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map.put("", tokens[0]);
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} else {
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map.put(tokens[0], "");
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}
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break;
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}
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case 2: {
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map.put(tokens[0], tokens[1]);
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break;
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}
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}
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}
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return map;
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}
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}
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