java - 使用接口(interface)时如何为类赋值？

Question

我有一个实现接口(interface)的Java类，这个类有一个接受字符串值的构造函数，并且该类的所有方法都依赖于该值才能工作，所以，如果我想要的话我能做什么直接处理接口(interface)并从中访问方法，正如您所知，接口(interface)不能有构造函数，因此我无法从中分配该字符串值。

类(class):

public class XmlSource implements XmlInterface{

    XmlConf xconf = new XmlConf();
    URLProcess urlp = new URLProcess();
    private URL url;
    private String surl;

    public XmlSource(String surl) throws MalformedURLException {

        this.surl = surl;
        result = urlp.validate(surl);
        if(result == true){
            configure();
        }

    }

    public boolean configure() throws MalformedURLException {

            url = new URL(surl);
            xconf.setUrl(url);
            xconf.setParameters(urlp.parameters);
            xconf.setUrlPath(urlp.path);
            xconf.setHostName(urlp.hostName);
            return result;

    }

    public Document load() throws IOException, ParserConfigurationException,
            SAXException {

        // encoding the URL
        InputStream is = url.openStream();

        // loading the XML
        domFactory = DocumentBuilderFactory.newInstance();
        domFactory.setNamespaceAware(true);
        builder = domFactory.newDocumentBuilder();
        doc = builder.parse(is);

        return doc;

        }
}

界面:

public interface XmlInterface {

    public boolean configure() throws Exception;
    public Document load() throws Exception;
}

Answer 1

您可以将 XmlSource 对象分配给 XmlInterface 类型引用变量，然后使用该引用变量调用方法。

XmlInterface obj = new XmlSource(surl);
try
{
    boolean configure = obj.configure();
    Document document = obj.load();
}
catch(Exception e){
 // perform exception handling
}