テンプレートエンジンfreemarkerでRSSを出力してみる

<?xml version="1.0" encoding="${encoding}"?>
<rss version="2.0">
    <channel>
        <title><![CDATA[${rss.title}]]></title>
        <link>${rss.link}</link>
        <description><![CDATA[${rss.description?default("No Description Given")}]]></description>
        <generator>pmplat@syboos.com</generator>
        <#list rss.items as item>
            <item>
                <title>${item.title}</title>
                <description><![CDATA[ ${item.description}]]></description>
                <guid isPermaLink="true">${item.link}</guid>
                <link>${item.link}</link>
                <pubDate><![CDATA[${item.publishDate}]]> GMT</pubDate>
            </item>
        </#list>
    </channel>
</rss>

public class RssData {
    private List items;
    private String title;
    private String description;
    private String encoding;
    private String link;
    private String publishDate;

    ...//コンストラクタ、setter/getterメソッドなど（略）
}

import freemarker.template.Configuration;
import freemarker.template.Template;


...

    private static Configuration templateCfg = null;
    
    public Template getTemplate(String filename) throws Exception {
    
        if (templateCfg == null) {
            try {
                templateCfg = new Configuration();    //
                templateCfg.setClassForTemplateLoading(this.getClass(), "/rss/");    //どこでRSSテンプレートを探すかを指定します
                templateCfg.setTemplateUpdateDelay(2);        //再ロードタイミング？
            } catch (Exception e) {
                throw e;
            }
        }
        
        try {
            return templateCfg.getTemplate(filename);    //テンプレートのファイル名からTemplate取得
        } catch (Exception e) {
            throw e;
        }
    }
    
...

Template templ = getTemplate("rss.tmpl");

    RssData rssData = new RssData();
    rssData.setXxxx(...);    //...
    ...

        Template templ = getTemplate("rss.tmpl");    //テンプレート取得
        StringWriter sw = new StringWriter();    //java.io.Writer
        
        SimpleHash templateContext = new SimpleHash();    //コンテキスト
        templateContext.put("encoding", "utf-8");    //データ：${encoding}
        templateContext.put("rss", rssData);    //データ：${rss.xxxx}
        
        templ.process(templateContext, sw);        //書き込む
        
        sw.toString();    //Stringへ出力