android基礎--列表項新增進度框
ListView、GridView列表項中清加ProgressBar,這裡用最簡單的程式碼實現可以通用的功能
如果你的介面卡getView方法返回的View是一個自定義控制元件的話，有點不好實現哦，不過可以用兩個控制元件之間Visible 、Invisible來切換實現今天的效果
下面的例子是主類、介面卡、非同步下載類等的都寫在一個類裡面了，其它控制元件列表項中新增進度框大家也可以用如下的方法實現
一：效果圖如下
核心程式碼如下：
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package com.example.listviewitemprogress;
import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL;
import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.AsyncTask; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.ImageView; import android.widget.ListView; import android.widget.ProgressBar; import android.widget.TextView;
/** * ListView列表項中新增ProgressBar */ public class MainActivity extends Activity { private ListView mListView = null ; private static final String imgUrl = "http://www.qq510.net/uploads/allimg/100613/2_100613171230_5.jpg";
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); }
private void init(){ mListView = (ListView)findViewById(R.id.listview); mListView.setAdapter(new MyListViewAdapter(this)); }
private class MyListViewAdapter extends BaseAdapter { private LayoutInflater inflater = null; public MyListViewAdapter(Context con){ inflater = (LayoutInflater)con.getSystemService(LAYOUT_INFLATER_SERVICE); }
@Override public int getCount() { // TODO Auto-generated method stub return Integer.MAX_VALUE; }
@Override public Object getItem(int arg0) { // TODO Auto-generated method stub return arg0; }
@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 mHolder = new ViewHolder() ; if(convertView == null) { convertView = inflater.inflate(R.layout.list_item, null); mHolder.iv = (ImageView)(convertView.findViewById(R.id.iv)); mHolder.mBtn = (Button)(convertView.findViewById(R.id.button)); mHolder.pb = (ProgressBar)(convertView.findViewById(R.id.progressBar1)); mHolder.tv = (TextView)(convertView.findViewById(R.id.textView1)); convertView.setTag(mHolder); }else{ mHolder = (ViewHolder)convertView.getTag(); }
new AsyncTask<ViewHolder, Void, Bitmap>() { private ViewHolder v;
@Override protected Bitmap doInBackground(ViewHolder... params) { v = params[0]; return BitmapFactory.decodeStream(getStreamFromURL(imgUrl)); }
@Override protected void onPostExecute(Bitmap result) { super.onPostExecute(result); v.pb.setVisibility(View.GONE); v.mBtn.setVisibility(View.VISIBLE); v.iv.setImageBitmap(result); } }.execute(mHolder); return convertView; } }
static class ViewHolder{ ImageView iv = null ; Button mBtn = null ; ProgressBar pb = null ; TextView tv = null ; }
static String length; public static InputStream getStreamFromURL(String imageURL) { InputStream in=null; try { URL url=new URL(imageURL); HttpURLConnection connection=(HttpURLConnection) url.openConnection(); // connection.setRequestProperty("Connection", "Keep-Alive");//維持長連線 connection.setConnectTimeout(6* 1000);//設定連線超時 if (connection.getResponseCode() != 200) throw new RuntimeException("請求失敗"); length = connection.getHeaderField("Content-Length"); in=connection.getInputStream(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } return in; } } |
佈局：
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主佈局檔案：
<RelativeLayout 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" >
<ListView android:id="@+id/listview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:drawSelectorOnTop="false" android:choiceMode="none" android:focusable="false" android:scrollingCache="false" android:fadingEdge="none" android:focusableInTouchMode="false" android:clickable="false" android:dividerHeight="0.5dip" />
</RelativeLayout>
ListView列表控制元件Item佈局：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="110dp" android:background="#00ffeeaa" >
<ImageView android:id="@+id/iv" android:layout_width="110dp" android:background="@drawable/ic_action_search" android:layout_height="110dp" android:contentDescription="@string/hello_world"/>
<Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentRight="true" android:layout_centerVertical="true" android:text="@string/xiaomaguo"/>
<ProgressBar android:id="@+id/progressBar1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_centerVertical="true" android:layout_alignTop="@+id/button" android:layout_marginLeft="29dp" />
<TextView android:id="@+id/textView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBaseline="@+id/button" android:layout_alignBottom="@+id/button" android:layout_centerVertical="true" android:layout_toLeftOf="@+id/button" android:text="@string/cool" />
</RelativeLayout> |
所需許可權：
<uses-permission android:name=”android.permission.INTERNET”/>