fileloader.java

来自「Boosting算法软件包」· Java 代码 · 共 86 行

/*
 * Created on Jan 15, 2004
 *
 */
package jboost.util;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Vector;

/**
 * This class provides a wrapper for loading data files
 * The loader will look for files in a several places,
 * similar to the way the ClassLoader uses the CLASSPATH
 * The primary search point will be relative to the JBOOST_HOME
 * By using FileLoader to load files, we centralize control
 * of where files are found.
 * If we enhance the Configuration implementation to use
 * Properties, some of the utility of this approach will go 
 * away, because file names can be specified using absolute
 * pathnames.
 * 
 * @author cschavis
 */
public class FileLoader {

  static private Vector d_path= new Vector(5);
  static private String JBOOST_HOME="jboost.home";
  
  // intialization of d_path
  static {
     // set up initial paths
    addDirectory(".");

    String home= System.getProperty(JBOOST_HOME);
    if (home != null) {
      addDirectory(home);
    }   
  }
   
  static public void addDirectory(String dirname) {
    System.out.println("Fileloader adding " + dirname + " to path.");
    d_path.addElement(dirname);
  }
  
  /**
   * @param filename
   * @return
   */
  static public FileReader createFileReader(String filename) 
    throws FileNotFoundException {

    if (filename == null) {
      throw new FileNotFoundException();
    }
    
    
    
    // try each element of path to see if works
    boolean finished= false;
    int index=0;
    FileReader result= null;

    while (!finished && index < d_path.size()) {
      try {
        result = new FileReader(filename);
        System.out.println("\tFound " + filename);
      } catch (FileNotFoundException fnf) {
        filename= d_path.get(index) + File.separator + filename;
        index++;
        continue;
      }
      finished= true;
    }
 
    // XXX: do we really want to throw here, or just return null?
    if (result == null) {
      throw new FileNotFoundException(filename);
    }
    
    return result;
  }
  
}