为了避免重复造轮子，我们一般都会封装一个通用的控件，比如这次，项目中需要用到比较多的 popupwindow ，如果需要一个个写，那么依旧会累死人，而且还是无用功，无意义，所以，封装一个通用的，除了让同事看了直刷666之外，自己还省了很多事情。

1、如何使用

那么，一般我们配置一个 PopupWindow 正常步骤需要多少代码呢？如下：

PopupWindow popupWindow = new PopupWindow(this);
    View contentview = LayoutInflater.from(this).inflate(R.layout.popup_calendar,null);
    popupWindow =
            new PopupWindow(contentview,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT,
                    true);
    //设置取消
    popupWindow.setOutsideTouchable(true);
    popupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));


    //设置位置
    View rootview = LayoutInflater.from(this).inflate(R.layout.activity_main,null);
    popupWindow.showAtLocation(rootview,Gravity.CENTER,0,0);

一般我们需要实现上面的基本代码，PopupWindow 才能跑起来，然后我们还需要添加动画，监听back键等等，然后，另外一个需要用到的时候，又得重复写，真的让人很绝望，这个时候，封装的思想就从脑袋冒出来了，那么，封装之后，怎么样的呢？如下：

CustomPopupWindow popupWindow = new CustomPopupWindow.Builder()
                    .setContext(this) //设置 context
                    .setContentView(R.layout.popup_calendar) //设置布局文件
                    .setwidth(LinearLayout.LayoutParams.WRAP_CONTENT) //设置宽度，由于我已经在布局写好，这里就用 wrap_content就好了
                    .setheight(LinearLayout.LayoutParams.WRAP_CONTENT) //设置高度
                    .setFouse(true)  //设置popupwindow 是否可以获取焦点
                    .setOutSideCancel(true) //设置点击外部取消
                    .setAnimationStyle(R.style.popup_anim_style) //设置popupwindow动画
                    .builder() //
                    .showAtLocation(R.layout.activity_calendar, Gravity.CENTER,0,0); //设置popupwindow居中显示

还有一种常见的情况，我们常用 popupwindow 作用 dialog，那么里面有 button 处理相应的逻辑。那如何想获取 PopupWindow 里面的控件怎么办？为了方便调用，这里我也采用用 id 的形式，所以，调用只要这样即可：

mMonthPicker = (PickerView) popupWindow.getItemView(R.id.picker_month);

然后就可以用 mMonthPicker 这个 view 搞事情了。

这样就把 contentview 中的控件取出来使用了，只要知道 id 就可以了，是不是方便了很多，都挺简单的，大家自己封装一边就ok全明白了

CustomPopupWindow 完整代码：

public  class CustomPopupWindow {
private PopupWindow mPopupWindow;
private View contentview;
private  Context mContext;
public CustomPopupWindow(Builder builder) {
    mContext = builder.context;
    contentview = LayoutInflater.from(mContext).inflate(builder.contentviewid,null);
    mPopupWindow =
            new PopupWindow(contentview,builder.width,builder.height,builder.fouse);

    //需要跟 setBackGroundDrawable 结合
    mPopupWindow.setOutsideTouchable(builder.outsidecancel);
    mPopupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

    mPopupWindow.setAnimationStyle(builder.animstyle);



}



/**
 * popup 消失
 */
public void dismiss(){
    if (mPopupWindow != null){
        mPopupWindow.dismiss();
    }
}

/**
 * 根据id获取view
 * @param viewid
 * @return
 */
public View getItemView(int viewid){
    if (mPopupWindow != null){
        return this.contentview.findViewById(viewid);
    }
    return null;
}

/**
 * 根据父布局，显示位置
 * @param rootviewid
 * @param gravity
 * @param x
 * @param y
 * @return
 */
public CustomPopupWindow showAtLocation(int rootviewid,int gravity,int x,int y){
    if (mPopupWindow != null){
        View rootview = LayoutInflater.from(mContext).inflate(rootviewid,null);
        mPopupWindow.showAtLocation(rootview,gravity,x,y);
    }
    return this;
}

/**
 * 根据id获取view ，并显示在该view的位置
 * @param targetviewId
 * @param gravity
 * @param offx
 * @param offy
 * @return
 */
public CustomPopupWindow showAsLaction(int targetviewId,int gravity,int offx,int offy){
    if (mPopupWindow != null){
        View targetview = LayoutInflater.from(mContext).inflate(targetviewId,null);
        mPopupWindow.showAsDropDown(targetview,gravity,offx,offy);
    }
    return this;
}

/**
 * 显示在 targetview 的不同位置
 * @param targetview
 * @param gravity
 * @param offx
 * @param offy
 * @return
 */
public CustomPopupWindow showAsLaction(View targetview,int gravity,int offx,int offy){
    if (mPopupWindow != null){
        mPopupWindow.showAsDropDown(targetview,gravity,offx,offy);
    }
    return this;
}


/**
 * 根据id设置焦点监听
 * @param viewid
 * @param listener
 */
public void setOnFocusListener(int viewid,View.OnFocusChangeListener listener){
    View view = getItemView(viewid);
    view.setOnFocusChangeListener(listener);
}


/**
 * builder 类
 */
public static class Builder{
    private int contentviewid;
    private int width;
    private int height;
    private boolean fouse;
    private boolean outsidecancel;
    private int animstyle;
    private Context context;

   public Builder setContext(Context context){
       this.context = context;
       return this;
   }


    public Builder setContentView(int contentviewid){
        this.contentviewid = contentviewid;
        return this;
    }

    public Builder setwidth(int width){
        this.width = width;
        return this;
    }
    public Builder setheight(int height){
        this.height = height;
        return this;
    }

    public Builder setFouse(boolean fouse){
        this.fouse = fouse;
        return this;
    }

    public Builder setOutSideCancel(boolean outsidecancel){
        this.outsidecancel = outsidecancel;
        return this;
    }
    public Builder setAnimationStyle(int animstyle){
        this.animstyle = animstyle;
        return this;
    }



    public CustomPopupWindow builder(){
       return new CustomPopupWindow(this);
    }
}

}