ClassFileLoader.java

package com.coderising.jvm.loader;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;

import com.coderising.jvm.clz.ClassFile;

public class ClassFileLoader {

	private List<String> clzPaths = new ArrayList<String>();

	public byte[] readBinaryCode(String className) {

		className = className.replace('.', File.separatorChar) + ".class";

		for (String path : this.clzPaths) {

			String clzFileName = path + File.separatorChar + className;
			byte[] codes = loadClassFile(clzFileName);
			if (codes != null) {
				return codes;
			}
		}

		return null;

	}

	private byte[] loadClassFile(String clzFileName) {

		File f = new File(clzFileName);

		try {

			return IOUtils.toByteArray(new FileInputStream(f));

		} catch (IOException e) {
			e.printStackTrace();
			return null;
		}
	}

	public void addClassPath(String path) {
		if (this.clzPaths.contains(path)) {
			return;
		}
		this.clzPaths.add(path);
	}

	public String getClassPath() {
		return StringUtils.join(this.clzPaths, ";");
	}

	public ClassFile loadClass(String className) {
		byte[] codes = this.readBinaryCode(className);
		ClassFileParser parser = new ClassFileParser();
		return parser.parse(codes);
	}

	// ------------------------------backup------------------------
	/*
	 * public String getClassPath_V1(){
	 * 
	 * StringBuffer buffer = new StringBuffer(); for(int
	 * i=0;i<this.clzPaths.size();i++){ buffer.append(this.clzPaths.get(i));
	 * if(i<this.clzPaths.size()-1){ buffer.append(";"); } } return
	 * buffer.toString(); }
	 * 
	 * private byte[] loadClassFile_V1(String clzFileName) {
	 * 
	 * BufferedInputStream bis = null;
	 * 
	 * try {
	 * 
	 * File f = new File(clzFileName);
	 * 
	 * 
	 * bis = new BufferedInputStream(new FileInputStream(f));
	 * 
	 * ByteArrayOutputStream bos = new ByteArrayOutputStream();
	 * 
	 * 
	 * byte[] buffer = new byte[1024]; int length = -1;
	 * 
	 * while((length = bis.read(buffer)) != -1){ bos.write(buffer, 0, length); }
	 * 
	 * byte [] codes = bos.toByteArray();
	 * 
	 * return codes;
	 * 
	 * } catch(IOException e){ e.printStackTrace();
	 * 
	 * } finally{ if(bis != null){ try { bis.close(); } catch (IOException e) {
	 * e.printStackTrace(); } } } return null;
	 * 
	 * }
	 * 
	 */

}