[C#]　AsinItemManager :　アマゾンの商品情報を最も取得できるライブラリ

using System.Xml;
 
//*********************************************************************
/// <summary> amazon商品情報の取得管理クラス 
/// </summary>
//*********************************************************************
class AsinItemManager {
 
    //*********************************************************************
    /// <summary> dan.co.jpのwebapiを使用してアマゾンの書籍情報を取得する
    /// example:
    ///    System.Xml.XmlDocument itemDoc = AsinBookManager.findByAsin("4003320212");
    ///    string asin     = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ASIN",     "" );
    ///    string title    = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ItemAttributes/Title",     "" );
    ///    string author   = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ItemAttributes/Author",     "" );
    ///    string binding  = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ItemAttributes/Binding",    "" );
    ///    string label    = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ItemAttributes/Label",      "" );
    ///    string newPrice = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ItemAttributes/ListPrice/FormattedPrice", "" );
    ///    string imageUrl = AsinBookManager.getNodeTextDef( itemDoc, "/opt/ImageSets/SwatchImage/URL", "" );
    ///    string linkUrl  = AsinBookManager.getNodeTextDef( itemDoc, "/opt/DetailPageURL", "" );
    /// </summary>
    /// 
    /// <param name="asin">	検索キー(ASIN)</param>
    /// <returns>書籍情報</returns>
    //*********************************************************************-
    public static XmlDocument findByAsin( string asin ) {
        string url = "http://api.dan.co.jp/asin/" + asin + ".xml";
        using ( XmlReader reader = XmlReader.Create( url ) ) {
            XmlDocument doc = new XmlDocument();
            doc.Load( reader );
            return doc;
        }
    }
 
    //*********************************************************************
    /// <summary> XmlDocumentから指定されたノードの情報を取得する
    /// </summary>
    /// <param name="doc">          取得対象のxml情報</param>
    /// <param name="xpath">        取得するノードのxpath式</param>
    /// <param name="defaultValue"> 指定したノードが無かったときの値</param>
    /// <returns>ノードのテキスト(InnerXml)</returns>
    //*********************************************************************
    public static string findNodeTextDef( XmlDocument doc, string xpath, string defaultValue ) {
        XmlNode node = doc.SelectSingleNode( xpath );
        if ( node == null ) {
            return defaultValue;
        } else {
            return node.InnerText;
        }
    }
 
    //*********************************************************************
    /// <summary> プライマリの商品画像一式を取得する
    /// example:
    ///     // System.Xml.XmlDocument itemDoc = AsinBookManager.findByAsin("4003320212");
    ///     System.Xml.XmlDocument itemDoc = AsinBookManager.findByAsin("4774166138");
    ///     System.Xml.XmlNode primaryImageSet = AsinBookManager.getPrimaryImageSet( itemDoc );
    ///     string imageUrl =  primaryImageSet.SelectSingleNode( "MediumImage/URL" ).InnerText;
    /// </summary>
    /// <param name="doc">取得対象のxml情報</param>
    /// <returns>ノードのテキスト(InnerXml)</returns>
    //*********************************************************************
    public static XmlNode getPrimaryImageSet( XmlDocument doc ) {
        System.Xml.XmlNode primaryImageSet = null;
 
        // ImageSets/ImageSetがある場合は、primaryなImageSetを取得する
        System.Xml.XmlNodeList imageNodeList = doc.SelectNodes( "/opt/ImageSets/ImageSet" );
        foreach ( System.Xml.XmlNode curNode in imageNodeList ) {
            string category = curNode.SelectSingleNode( "Category" ).InnerText;
            if ( category != "primary" ) {
                continue;
            }
 
            primaryImageSet = curNode;
            break;
        }
 
        // ImageSets/ImageSetがなかった場合は、ImageSetsをprimaryとみなす
        if ( primaryImageSet == null ) {
            primaryImageSet = doc.SelectSingleNode( "/opt/ImageSets" );
        }
 
        return primaryImageSet;
    }
}

string keyAsin = "4774166138"; // "4003320212"
 
var itemDoc = AsinBookManager.findByAsin( keyAsin );
string asin     = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ASIN",     "" );
string title    = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/Title",      "" );
string author   = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/Author",     "" );
string binding  = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/Binding",    "" );
string label    = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/Label",      "" );
string pubDate  = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/PublicationDate", "" );
string newPrice = AsinBookManager.findNodeTextDef( itemDoc, "/opt/ItemAttributes/ListPrice/FormattedPrice", "" );
string linkUrl  = AsinBookManager.findNodeTextDef( itemDoc, "/opt/DetailPageURL", "" );
 
System.Xml.XmlNode primaryImageSet = AsinBookManager.getPrimaryImageSet( itemDoc );
string imageUrl = primaryImageSet.SelectSingleNode( "MediumImage/URL" ).InnerText;