Android 封裝popwindow類,實現所有activity共用
阿新 • • 發佈:2019-01-28
popwindow是一個彈出window,在此對其進行封裝,使這個popwindow可以在所有頁面都顯示。
這樣一來就會出現一個問題,定義popwindow上的item的點選事件做相應的動作的時候,就會提示空指標異常,從而強制退出程式。如下將分析如何解決。
定義公用類 以便呼叫所有activity呼叫。
package com.ytumobilelibrary.common;
import com.ytumobilelibrary.readerservice.LoginActivity;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ImageButton;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
public class CommonPopWindowActivity extends Activity {
private PopMenu popMenu; // 此popmenu是2中定義的popwindow生成類
private Context context;
private Context current_activity;
private static CommonPopWindowActivity instance;
public synchronized static CommonPopWindowActivity getInstance() {
if (null == instance) {
instance = new CommonPopWindowActivity();
}
return instance;
}
public void buildPopWindow(Activity activity, ImageButton popWind) {
this.context = activity;
popMenu = new PopMenu(context);
popMenu.addItems(new String[] { "登入", "登出", "使用說明", "關於軟體" });
// 選單項點選監聽器
popMenu.setOnItemClickListener(popmenuItemClickListener);
popWind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
popMenu.showAsDropDown(v);
}
});
}
// 彈出選單監聽器
OnItemClickListener popmenuItemClickListener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
current_activity = view.getContext();
// current_activity 的定義是為了取得呼叫此方Activity
//的本身例項,這樣才不會報空指標異常。
System.out.println("下拉選單點選" + position);
// 取得item上的值
// HashMap<String, Object> item = (HashMap<String, Object>)
// adapterView
// .getItemAtPosition(position);
Intent intent = new Intent();
intent.putExtra("Flag", RS_FLAG);
intent.setClass(current_activity, LoginActivity.class);
((Activity) current_activity).startActivityForResult(
intent, 5);
popMenu.dismiss();
};
}
定義pop類
package com.ytumobilelibrary.common;
import java.util.ArrayList;
import com.ytumobilelibrary.R;
import android.content.Context;
import android.graphics.drawable.BitmapDrawable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.PopupWindow;
import android.widget.TextView;
public class PopMenu {
private ArrayList<String> itemList;
private Context context;
private PopupWindow popupWindow;
private ListView listView;
// private OnItemClickListener listener;
public PopMenu(Context context) {
this.context = context;
itemList = new ArrayList<String>(5);
View view = LayoutInflater.from(context).inflate(R.layout.popmenu, null);
// 設定 listview
listView = (ListView) view.findViewById(R.id.popwin_listView);
listView.setAdapter(new PopAdapter());
listView.setFocusableInTouchMode(true);
listView.setFocusable(true);
// popupWindow = new PopupWindow(view, 100, LayoutParams.WRAP_CONTENT);
popupWindow = new PopupWindow(view, context.getResources().getDimensionPixelSize(R.dimen.popmenu_width),
context.getResources().getDimensionPixelSize(R.dimen.popmenu_height));
// context.getResources()
// .getDimensionPixelSize(R.dimen.popmenu_width)
// 這個是為了點選“返回Back”也能使其消失,並且並不會影響你的背景(很神奇的)
popupWindow.setBackgroundDrawable(new BitmapDrawable());
}
// 設定選單項點選監聽器
public void setOnItemClickListener(OnItemClickListener listener) {
// this.listener = listener;
listView.setOnItemClickListener(listener);
}
// 批量新增選單項
public void addItems(String[] items) {
for (String s : items)
itemList.add(s);
}
// 單個新增選單項
public void addItem(String item) {
itemList.add(item);
}
// 下拉式 彈出 pop選單 parent 右下角
public void showAsDropDown(View parent) {
popupWindow.showAsDropDown(parent, 10,
// 保證尺寸是根據螢幕畫素密度來的
context.getResources().getDimensionPixelSize(R.dimen.popmenu_yoff));
// 使其聚集
popupWindow.setFocusable(true);
// 設定允許在外點選消失
popupWindow.setOutsideTouchable(true);
// // 重新整理狀態
popupWindow.update();
}
// 隱藏選單
public void dismiss() {
popupWindow.dismiss();
}
// 介面卡
private final class PopAdapter extends BaseAdapter {
@Override
public int getCount() {
// TODO Auto-generated method stub
return itemList.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return itemList.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
ViewHolder holder;
if (convertView == null) {
convertView = LayoutInflater.from(context).inflate(R.layout.pomenu_item, null);
holder = new ViewHolder();
convertView.setTag(holder);
holder.groupItem = (TextView) convertView.findViewById(R.id.popwin_textView);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.groupItem.setText(itemList.get(position));
return convertView;
}
private final class ViewHolder {
TextView groupItem;
}
}
}
pomenu_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="120.0dip"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center_vertical"
android:background="@drawable/bg_pop_item" >
<TextView
android:id="@+id/popwin_textView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10.0dip"
android:gravity="center"
android:text="測試"
android:textColor="#FFFFFF"
android:textSize="17.0dip" />
</LinearLayout>
pomenu.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/popup_view_cont"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
>
<ListView
android:id="@+id/popwin_listView"
android:layout_width="fill_parent"
android:layout_height="0.0dip"
android:layout_weight="1.0"
android:background="@drawable/map_tips"
android:cacheColorHint="#00000000"
android:divider="@drawable/line2"
android:dividerHeight="4.0dip"
android:focusable="true"
android:scrollbars="none" >
</ListView>
</LinearLayout>
bg_pop_item.xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/home_btn_bg_s"
android:state_pressed="true"/>
<item android:drawable="@drawable/home_btn_bg_s"
android:state_enabled="true"
android:state_focused="true"/>
<item android:drawable="@drawable/home_btn_bg_s"
android:state_checked="true"
android:state_enabled="true"
></item>
</selector>
在所有Activity中呼叫公用類CommonPopWindowActivity 的方法如下:
//ImageButton 是所有activity中定義的ImageButton,點選此bt可以彈出popwindow
ImageButton popWind = (ImageButton) findViewById(R.id.radio_button4);
//載入popwindow this就是該activity的例項,這樣在CommonPopWindowActivity類中跳轉頁面或者彈出toast才不會報空指標異常
CommonPopWindowActivity.getInstance().buildPopWindow(this,popWind);