Android中的PopupWindow的使用

直接看代码：

public class ThirdActivity extends Activity{
    private Button but , but1 ;
    private AlertDialog dialog ;
    private AlertDialog.Builder builder;
    private ProgressDialog progressDialog ;
    private SexDialog dialogBottom ;
    private PopupWindow popupWindow ;
    private View popupWindowView ;
    private WindowManager.LayoutParams lp ;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView( R.layout.thirdlayout);
        but = (Button) findViewById( R.id.but3);
        but1 = (Button) findViewById( R.id.but33);
        initPopupWindow();
        but1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (popupWindow.isShowing()){
                    popupWindow.dismiss();
                }else{
                    backgroundAlpha(ThirdActivity.this , 0.5f);
                    popupWindow.showAsDropDown(v);
                }
            }
        });
    }

    /**
     * popudWindow初始化
     */
    private void initPopupWindow(){
        popupWindowView = LayoutInflater.from(this).inflate(R.layout.popmenu_add2, null);
        popupWindow = new PopupWindow(popupWindowView, ViewPager.LayoutParams.WRAP_CONTENT, ViewPager.LayoutParams.WRAP_CONTENT);
        //设置点击窗口外边窗口消失
        popupWindow.setBackgroundDrawable(new BitmapDrawable());
        popupWindow.setOutsideTouchable(true);
        // 设置此参数获得焦点，否则无法点击
        popupWindow.setFocusable(true);
        popupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {
            @Override
            public void onDismiss() {
                backgroundAlpha(ThirdActivity.this , 1f);
            }
        });
    }

    /**
     * 设置popupwindow背景显示变暗
     */
    public void backgroundAlpha(Activity activity, float bgAlpha) {
        lp = this.getWindow().getAttributes();
        lp.alpha = bgAlpha;
        activity.getWindow().setAttributes(lp);
    }
}

popmenu_add2.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:background="#ffffff"
              android:orientation="vertical"
              android:padding="10dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:drawableLeft="@drawable/menu_scan"
        android:drawablePadding="10dp"
        android:text="扫一扫"
        android:textColor="#ff333333"
        android:textSize="16sp"/>

</LinearLayout>

使用popupWindow是需要注意的几个问题

1 . 由于popupWindow没有继承ViewGroup类，所以inflatter.inflater()的第二个参数只能传null，传null时会使最外层的布局android：layout_XXX都不起作用。所以高度一第二个布局为主。

2 . 为了设置背景和边距，其背景只能设置在第二层布局里，由于第一层布局的android：layout_xxx都不起作用，而设置android：apping_xxx也不影响背景。

3 . 为了点击popupWindow的外面能消失，几个属性需要一起设置破噗噗Window.setOutsideTouchable(true) ;popupWindow.setBackgroundDrawable()