java Runtime如何执行多条命令

public static void cmd()  {

         String ls = "  cd /home/ &&  dir " ;

         Process process = null ;

         String cmd = getOsCmd()+ ls;

         try {

             process = Runtime.getRuntime().exec(cmd);

             BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(process.getInputStream()));

             String line = null ;

             while ((line = bufferedReader.readLine()) != null ) {

                 System.out.println( new String(line.getBytes(), "GBK" ));

             }

         } catch (Exception e){

             e.printStackTrace();

         }

         finally {

             process.destroy();

         }

     }

     public static String getOsCmd(){

         Properties props=System.getProperties(); //获得系统属性集

         String osName = props.getProperty( "os.name" ); //操作系统名称

         if (osName.toLowerCase().contains( "linux" )){

             return "/bin/sh -c" ;

         } else if (osName.toLowerCase().contains( "windows" )){

             return "cmd /c" ;

         } else {

             throw new RuntimeException( "服务器不是linux|windows操作系统" );

         }

     }

Runtime.getRuntime().exec( "cmd1 && " +

"cmd2 && " +

"cmd3 && " );