android弹出框之.showAsDropDown(View anchor, int xoff, int yoff)：PopupWindow使用详解

android中弹出框有两种，AlertDialog和PopupWindow,PoppupWindow是悬浮在当期Activity上的，相对于AlertDialog来说，位置比较随意，可以在代码中设置弹出框要显示的位置。

PopupWindow的常用设置

.showAsDropDown(view);//相对某个控件的位置（正左下方），无偏移  

.showAsDropDown(View anchor, int xoff, int yoff)：//相对某个控件的位置，有偏移;xoff表示x轴的偏移，正值表示向左，负值表示向右；yoff表示相对y轴的偏移，正值是向下，负值是向上； 

.showAtLocation(contentView, Gravity.BOTTOM, 0, 0); //相对于父控件的位置（例如正中央Gravity.CENTER，下方Gravity.BOTTOM等），可以设置偏移或无偏移

.setOutsideTouchable(true);//点击popupwindow外部消失

.setFocusable(true);//获取焦点

.setOnDismissListener(this);//加上上面两句让popupwindow自动消失

.setBackgroundDrawable(getResources().getDrawable(R.drawable.bg_pupwindow));// 如果不设置PopupWindow的背景，无论是点击外部区域还是Back键都无法dismiss弹框

下面附Popupwindow弹出框和PopupWindow做下拉列表完整例子

MainActivity完整代码

<span style="font-size:18px;color:#006600;">public class MainActivity extends Activity implements OnItemClickListener, OnDismissListener {

private Button button1;//单个popupwindow点击按钮

private TextView button2;//下拉 popupwindow点击按钮

private ListView listview;

private PopupWindowAdapter adapter;

private PopupWindow typePopupWindow;

private boolean isPopShow = false;

List<String> list;
@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

button1=(Button) findViewById(R.id.button1);
button2=(TextView) findViewById(R.id.button2);

listview=new ListView(this);
listview.setOnItemClickListener(this);
adapter=new PopupWindowAdapter(this);
List<String> list=getList();
adapter.setData(list);
button1.setOnClickListener(new SubmitBtn1());
//button2的点击事件
button2.setOnClickListener(new SubmitBtn2());
}
public class SubmitBtn1 implements OnClickListener{

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
showPopupWindow(v);

}

}

public class SubmitBtn2 implements OnClickListener{

@Override
public void onClick(View v) {
// TODO Auto-generated method stub

listview.setAdapter(adapter);
initTypePopup(button2.getWidth());

if(typePopupWindow != null && !isPopShow) {
typePopupWindow.showAsDropDown(button2, 2, 0);
isPopShow = true;
}
}

}

private void showPopupWindow(View view) {

// 一个自定义的布局，作为显示的内容
View contentView = LayoutInflater.from(this).inflate(
R.layout.popupwindow, null);
// 设置按钮的点击事件
Button button = (Button) contentView.findViewById(R.id.btn_pop);
button.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
Toast.makeText(MainActivity.this, "button is pressed",
Toast.LENGTH_SHORT).show();
onDismiss();
}
});
//这里从新设置了popupWindow的width和heigth,就会以此处为标准
PopupWindow popupWindow = new PopupWindow(contentView,
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, true);

popupWindow.setTouchable(true);
popupWindow.setTouchInterceptor(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return false;
// 这里如果返回true的话，touch事件将被拦截
//          // 拦截后 PopupWindow的onTouchEvent不被调用，这样点击外部区域无法dismiss

}
});

// 如果不设置PopupWindow的背景，无论是点击外部区域还是Back键都无法dismiss弹框 ，我觉得这里是API的一个bug
popupWindow.setBackgroundDrawable(getResources().getDrawable(R.drawable.bg_pupwindow));

//相对某个控件的位置（正左下方），无偏移
//    popupWindow.showAsDropDown(view);//相对某个控件的位置（正左下方），无偏移

//相对某个控件的位置，有偏移;xoff表示x轴的偏移，正值表示向左，负值表示向右；yoff表示相对y轴的偏移，正值是向下，负值是向上；
//    popupWindow.showAsDropDown(View anchor, int xoff, int yoff)：

//  相对于父控件的位置（例如正中央Gravity.CENTER
4000
，下方Gravity.BOTTOM等），可以设置偏移或无偏移
popupWindow.showAtLocation(contentView, Gravity.BOTTOM, 0, 0);

}

//自定义一个popupwindow;
private void initTypePopup(int width) {
typePopupWindow = new PopupWindow(listview, width,
LayoutParams.WRAP_CONTENT, true);
Drawable drawable = getResources().getDrawable(R.drawable.bg_pupwindow);
typePopupWindow.setBackgroundDrawable(drawable);
typePopupWindow.setOutsideTouchable(true);//点击popupwindow外部消失
typePopupWindow.setFocusable(true);//获取焦点
typePopupWindow.setOnDismissListener(this);//加上上面两句让破噗噗window自动消失

}

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
Toast.makeText(MainActivity.this, "您选择了"+adapter.getItem(position), 0).show();//显示选择的内容

typePopupWindow.dismiss();//关闭popupwindow窗口;
}
//定义一个list集合
private List<String> getList(){
list=new ArrayList<String>();
for(int i=0;i<100;i++){
list.add("spinner"+i);
}
return list;
}

@Override
public void onDismiss() {
// TODO Auto-generated method stub
isPopShow = false;

}
}</span>

activity_main.xml

<span style="color:#33cc00;"><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.popupwindow.MainActivity"
android:orientation="vertical"
>

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="单个的popupwindow"
android:textSize="20sp"
/>
<TextView
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="popupwindow下拉列表"
android:textSize="20sp"
android:textColor="#123eee"
/>

</LinearLayout>
</span>

popupwindow_item.xml

<span style="color:#33cc00;"><?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffffff"
android:padding="10dp"
android:textSize="20dp"
android:id="@+id/tv_popupwindow"
>
</TextView>
</span>

popupwindow.xml

<span style="color:#33cc00;"><?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:orientation="vertical"
android:background="#ffffff"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="单个popupwindow"
android:textSize="30dp"
android:layout_gravity="center_horizontal"
/>
<Button
android:id="@+id/btn_pop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="确定"
android:layout_gravity="center_horizontal"

/>
</LinearLayout>
</span>

PopupWindowAdapter完整代码

<span style="color:#33cc00;">public class PopupWindowAdapter extends BaseAdapter{

private Context context;

private List<String> list;

public PopupWindowAdapter(Context context){
this.context=context;
}

public void setData(List<String> lists){
list=lists;
this.notifyDataSetChanged();

}

@Override
public int getCount() {
// TODO Auto-generated method stub
return list.size();
}

@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return list.get(position);
}

@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
HolderView holderView=null;
if(null==convertView){
holderView=new HolderView();
convertView=LayoutInflater.from(context).inflate(R.layout.popupwindow_item,  parent,false);
holderView.time= (TextView) convertView.findViewById(R.id.tv_popupwindow);
convertView.setTag(holderView);
}else{
holderView = (HolderView) convertView.getTag();
}
String time=(String) getItem(position);
holderView.time.setText(time);

return convertView;
}

class HolderView {
TextView time;
}

}
</span>