Java实现从jar包中读取指定文件的方法

/**
* This class implements the funcationality of reading and writing files in jar files.
*/
package com.leo.util;
import java.io.InputStream;
import java.io.FileOutputStream;
import java.util.jar.*;
import java.util.Enumeration;
/**
* @author Leo Share
* @since 08/09/2007
* @version 1.0
*/
public class JarFileAccess {
  private static final String fileSeparator = System.getProperty("file.separator");
  public void accessJarFile(String jarFileName, String fromDir, String toDir) throws Exception{
    JarFile myJarFile = new JarFile(fromDir+fileSeparator+jarFileName);
    Enumeration myEnum = myJarFile.entries();
    while(myEnum.hasMoreElements()){
      JarEntry myJarEntry = (JarEntry)myEnum.nextElement();
      if(myJarEntry.getName().equals("jbossall-client.jar")){
        InputStream is = myJarFile.getInputStream(myJarEntry);
        FileOutputStream fos = new FileOutputStream(toDir+fileSeparator+myJarEntry.getName());
        byte[] b = new byte[1024];
        int len;
        while((len = is.read(b))!= -1){
          fos.write(b, 0, len);
        }
        fos.close();
        is.close();
        break;
      } else{
        continue;
      }
    }
    myJarFile.close();
  }
}