核心就是隐藏构造方法，通过一个静态内部类封装构造。隐藏构建过程。

主要使用于对象比较复杂的时候， Android中我们使用最多的就是AlertDialog了。

public class MediaPlayer {
    private LivingPlayer livingPlayer;
    private VidoPlayter vidoPlayter;
    private String PlayUrl;
    private Callback mcallback;

    public MediaPlayer(Builder builder) {
        this.livingPlayer=builder.livingPlayer;
        this.vidoPlayter=builder.vidoPlayter;
        this.PlayUrl=builder.PlayUrl;
        this.mcallback=builder.mcallback;
    }
    interface Callback {
        void callback();
    }
    public static class Builder{
        private LivingPlayer livingPlayer;
        private VidoPlayter vidoPlayter;
        private String PlayUrl;
        private Callback mcallback;

        public Builder setLivingPlayer(LivingPlayer livingPlayer) {
            this.livingPlayer = livingPlayer;
            return this;
        }

        public Builder setVidoPlayter(VidoPlayter vidoPlayter) {
            this.vidoPlayter = vidoPlayter;
            return this;
        }
        public Builder setPlayUrl(String playUrl) {
            PlayUrl = playUrl;
            return this;
        }
        public Builder setCallback(  Callback callback) {
            mcallback = callback;
            return this;
        }

        public MediaPlayer build(){
            return  new MediaPlayer(this);
        }
    }
}

使用

        MediaPlayer.Builder builder=new MediaPlayer.Builder();
        builder.setLivingPlayer(new LivingPlayer(AppApplication.appContext));
        MediaPlayer livingplayer=builder.build();