systemclassloader.java

Java源码

package AM.vm_impl.util;

/**
 * Created by IntelliJ IDEA. User: yellowicq Date: 2004-4-27 Time: 13:16:40
 * To change this template use File | Settings | File Templates.
 */

import java.io.*;

public class SystemClassLoader
    extends ClassLoader {

  // basePath gives the path to which this class
  // loader appends "/<typename>.class" to get the
  // full path name of the class file to load
  private String basePath;

  public SystemClassLoader(String basePath) {

    this.basePath = basePath;
  }

  public SystemClassLoader(ClassLoader parent, String basePath) {

    super(parent);
    this.basePath = basePath;
  }

  protected Class findClass(String className) throws ClassNotFoundException {

    byte classData[];

    // Try to load it from the basePath directory.
    classData = getTypeFromBasePath(className);
    if (classData == null) {
      throw new ClassNotFoundException();
    }

    // Parse it
    return defineClass(className, classData, 0,
                       classData.length);
  }

  private byte[] getTypeFromBasePath(String typeName) {

    FileInputStream fis;
    String fileName = basePath + File.separatorChar
        + typeName.replace('.', File.separatorChar)
        + ".class";

    try {
      fis = new FileInputStream(fileName);
    }
    catch (FileNotFoundException e) {
      return null;
    }

    BufferedInputStream bis = new BufferedInputStream(fis);

    ByteArrayOutputStream out = new ByteArrayOutputStream();

    try {
      int c = bis.read();
      while (c != -1) {
        out.write(c);
        c = bis.read();
      }
    }
    catch (IOException e) {
      return null;
    }

    return out.toByteArray();
  }
}