extensionfilehandler.java

LuceneInAction配套源码,LuceneInAction是对lucene api的详细讲解及具体应用.此源码即应用例子

package lia.handlingtypes.framework;

import org.apache.lucene.document.Document;

import java.io.File;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.Properties;

/**
 * A FileHandler implementation that delegates responsibility to
 * appropriate DocumentHandler implementation, based on a file
 * extension.
 */
public class ExtensionFileHandler implements FileHandler {
  private Properties handlerProps;

  public ExtensionFileHandler(Properties props) {
    handlerProps = props;
  }

  public Document getDocument(File file)
    throws FileHandlerException {

    String name = file.getName();
    int dotIndex = name.indexOf(".");
    if ((dotIndex > 0) && (dotIndex < name.length())) {
      String ext = name.substring(dotIndex + 1, name.length());
      String handlerClassName = handlerProps.getProperty(ext);

      if (handlerClassName == null)
        return null;

      try {
        Class handlerClass = Class.forName(handlerClassName);
        DocumentHandler handler =
          (DocumentHandler) handlerClass.newInstance();
        return handler.getDocument(new FileInputStream(file));
      }
      catch (ClassNotFoundException e) {
        throw new FileHandlerException(
          "Cannot create instance of : "
          + handlerClassName, e);
      }
      catch (InstantiationException e) {
        throw new FileHandlerException(
          "Cannot create instance of : "
          + handlerClassName, e);
      }
      catch (IllegalAccessException e) {
        throw new FileHandlerException(
          "Cannot create instance of : "
          + handlerClassName, e);
      }
      catch (FileNotFoundException e) {
        throw new FileHandlerException(
          "File not found: "
          + file.getAbsolutePath(), e);
      }
      catch (DocumentHandlerException e) {
        throw new FileHandlerException(
          "Document cannot be handler: "
          + file.getAbsolutePath(), e);
      }
    }
    return null;
  }

  public static void main(String[] args) throws Exception {
    if (args.length < 2) {
      usage();
      System.exit(0);
    }

    Properties props = new Properties();
    props.load(new FileInputStream(args[0]));

    ExtensionFileHandler fileHandler =
      new ExtensionFileHandler(props);
    Document doc = fileHandler.getDocument(new File(args[1]));
    System.out.println(doc);
  }

  private static void usage() {
    System.err.println("USAGE: java "
      + ExtensionFileHandler.class.getName()
      + " /path/to/properties /path/to/document");
  }
}