java自定义ClassLoader加载指定的class文件操作

package cn.lijie;

public class mytest {

   public void show() {

     system.out.println( "show test!" );

   }

}

public class myclassloader extends classloader {

   @override

   protected class <?> findclass(string name) {

     string mypath = "file:///users/allen/desktop/" + name.replace( "." , "/" ) + ".class" ;

     system.out.println(mypath);

     byte [] classbytes = null ;

     path path = null ;

     try {

       path = paths.get( new uri(mypath));

       classbytes = files.readallbytes(path);

     } catch (ioexception | urisyntaxexception e) {

       e.printstacktrace();

     }

     class clazz = defineclass(name, classbytes, 0 , classbytes.length);

     return clazz;

   }

}

public class mainclass {

   public static void main(string[] args) throws classnotfoundexception {

     myclassloader loader = new myclassloader();

     class <?> aclass = loader.findclass( "cn.lijie.mytest" );

     try {

       object obj = aclass.newinstance();

       method method = aclass.getmethod( "show" );

       method.invoke(obj);

     } catch (exception e) {

       e.printstacktrace();

     }

   }

}

import java.io.bytearrayoutputstream;

import java.io.ioexception;

import java.io.inputstream;

import ch.ethz.ssh2.connection;

import ch.ethz.ssh2.sftpinputstream;

import ch.ethz.ssh2.sftpv3client;

public class fs{

  public static void main(string[] args) throws exception {

  ownclassloader ocl = new ownclassloader();

  string ip,user,password;

  ip = "120.34.168.80" ; //自己的远程ip

  user = "root" ; //username

  password = "123456" ; //password

  ocl.login(ip, user, password);

  object obj = ocl.loadeothclass( "/opt/4/tt.class" ); //class文件路径

  system.out.println(obj);

  class c = obj.getclass();

  field f = c.getdeclaredfield( "age" );

  f.setaccessible( true );

  system.out.println( "age:" +f.get(obj));

  }

}

//自定义类加载器

class ownclassloader extends classloader{

  private connection conn = null ;

  //初始化链接

  public connection login(string ip,string user,string password){

  connection conn = null ;

  try {

   //也可以new connection(ip, port)创建对象,默认22

   conn = new connection(ip);

   //连接远程服务

   conn.connect();

   //使用用户名和密码登录

   conn.authenticatewithpassword(user, password);

   this .conn = conn;

      return conn;

  } catch (ioexception e) { 

   e.printstacktrace();

   }

   return null ;

  }

  //返回远程实例

  public object loadeothclass(string url) throws exception{

  if ( null ==conn)

   throw new exception( "请初始化链接" );

  sftpv3client sc = new sftpv3client(conn); //创建ssh客户端连接

  inputstream is = new sftpinputstream(sc.openfilero(url)); //创建输入流

  byte [] b = this .readclassfile(is);

  class <?> c = super .defineclass(b, 0 , b.length); //定义class

  return c.newinstance(); //创建实例

  }

  //读取远程class文件

  private byte [] readclassfile(inputstream is){

  byte [] b = new byte [ 1024 ];

  int len;

  bytearrayoutputstream bos = null ;

  try {

   bos = new bytearrayoutputstream(); //内存流输出

   while ((len=is.read(b))!=- 1 ){

   bos.write(b, 0 , len);

   }

   b = bos.tobytearray();

  } catch (exception e) {

   // todo auto-generated catch block

   e.printstacktrace();

  } finally {

   try {

   if (is!= null )

    is.close();

   if (bos!= null )

    bos.close();

   } catch (exception e2) {

   // todo: handle exception

   }

  }

  return b;

  }

}