封装popwindow类，实现所有activity共用

来源：互联网发布：最优化算法 pdf 编辑：程序博客网时间：2024/05/22 16:58

popwindow是一个弹出window，在此对其进行封装，使这个popwindow可以在所有页面都显示。

在CSDN上有类似的封装类供下载，可以去自行下载然后做修改。附上地址：http://download.csdn.net/download/duanyu218/5045677

这样一来就会出现一个问题，定义popwindow上的item的点击事件做相应的动作的时候，就会提示空指针异常，从而强制退出程序。如下将分析如何解决：

1、定义公用类以便调用所有activity调用

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中定义的popwindow生成类
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[] { "登录", "注销","使用说明", "关于软件" });
// 菜单项点击监听器
popMenu.setOnItemClickListener(popmenuItemClickListener);

popWind.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {

popMenu.showAsDropDown(v);
}

});

}
// 弹出菜单监听器
OnItemClickListener popmenuItemClickListener = new OnItemClickListener() {

@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {

current_activity = view.getContext();

// current_activity 的定义是为了取得调用此方Activity

//的本身实例，这样才不会报空指针异常。

System.out.println("下拉菜单点击" + 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();

};

}

2、定义pop类
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);

// 设置 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)
// 这个是为了点击“返回Back”也能使其消失，并且并不会影响你的背景（很神奇的）
popupWindow.setBackgroundDrawable(new BitmapDrawable());
}

// 设置菜单项点击监听器
public void setOnItemClickListener(OnItemClickListener listener) {
// this.listener = listener;
listView.setOnItemClickListener(listener);
}

// 批量添加菜单项
public void addItems(String[] items) {
for (String s : items)
itemList.add(s);
}

// 单个添加菜单项
public void addItem(String item) {
itemList.add(item);
}

// 下拉式弹出 pop菜单 parent 右下角
public void showAsDropDown(View parent) {
popupWindow.showAsDropDown(parent,
10,
// 保证尺寸是根据屏幕像素密度来的
context.getResources().getDimensionPixelSize(
R.dimen.popmenu_yoff));

// 使其聚集
popupWindow.setFocusable(true);
// 设置允许在外点击消失
popupWindow.setOutsideTouchable(true);
// // 刷新状态
popupWindow.update();
}

// 隐藏菜单
public void dismiss() {
popupWindow.dismiss();
}

// 适配器
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;
}
}
}
3、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" > //点击item的变化图片如5所示

4、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"
>

</LinearLayout>

5、bg_pop_item.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

</selector>

在所有Activity中调用公用类CommonPopWindowActivity 的方法如下：

// ImageButton 是所有activity中定义的ImageButton，点击此bt可以弹出popwindow

ImageButton popWind = (ImageButton) findViewById(R.id.radio_button4);
//加载popwindow this就是该activity的实例，这样在CommonPopWindowActivity类中跳转页面或者弹出toast才不会报空指针异常
CommonPopWindowActivity.getInstance().buildPopWindow(this,popWind);

0 0