public class Computer {

    private String mBoard;

    private String mDisplay;

    private String mOS;

    public String getmBoard() {

        return mBoard;

    }

    public void setmBoard(String mBoard) {

        this.mBoard = mBoard;

    }

    public String getmDisplay() {

        return mDisplay;

    }

    public void setmDisplay(String mDisplay) {

        this.mDisplay = mDisplay;

    }    

    public String getmOS() {

        return mOS;

    }

    public void setmOS() {

       this.mOS = mOS;

    }

    public static class Builder {

        private String mBoard;

        private String mDisplay;

       private String mOS;

       public Builder setBoard(String board) {

            this.mBoard = board;

            return this;

       }

        public Builder setDisplay(String display) {

            this.mDisplay = display;

            return this;

        }

        public Builder setOs() {

            return this;

        }

    /**

     * 组装产品

     */

    private void construct(Computer computer) {

        computer.setmBoard(mBoard);

        computer.setmDisplay(mDisplay);

        computer.setmOS();

    }

    public Computer create() {

        Computer computer = new Computer();

        construct(computer);

        return computer;

    }

}

Computer computer = new Computer.Builder().setBoard("")

                .setDisplay("")

                .setOs()

                .create();