ListView中顯示網(wǎng)絡(luò)圖片

2011-05-20 10:48:22

最近在做一個(gè)天氣預(yù)報(bào)的例子，想在ListView中添加網(wǎng)絡(luò)圖片，在翻閱很多文檔，在Baidu上Google很久，終于找到了辦法，現(xiàn)在跟大家分享一下解決方案，此篇僅做一個(gè)比較簡(jiǎn)單的實(shí)例；

大家知道ImageView 類(lèi)雖然有一個(gè) setImageUri 方法，但不能直接接受一個(gè)由網(wǎng)絡(luò)地址生成的uri作為參數(shù)從而顯示圖片，我們只好使用其 setImageBitmap 方法，如

Bitmap mBitmap = null; URL url = new URL(imageUrl); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); InputStream is = conn.getInputStream(); mBitmap = BitmapFactory.decodeStream(is);

在SimpleAdapter中需要一個(gè)數(shù)據(jù)源，用來(lái)存儲(chǔ)數(shù)據(jù)的，在顯示圖片時(shí)我們要用HashMap<>存儲(chǔ)一個(gè)Bitmap；但僅存取了Bitmap時(shí)在ListView中是無(wú)法顯示圖片的，我們需要對(duì)SimpleAdapter進(jìn)行處理 。

如下是對(duì)SimpleAdaptr處理的主要代碼：

adapter.setViewBinder(new ViewBinder() { public boolean setViewValue(View view, Object data, String textRepresentation) { //判斷是否為我們要處理的對(duì)象 if(view instanceof ImageView && data instanceof Bitmap){ ImageView iv = (ImageView) view; iv.setImageBitmap((Bitmap) data); return true; }else return false; } });

看API對(duì)android.widget.SimpleAdapter.ViewBinder的解釋?zhuān)?

This class can be used by external clients of SimpleAdapter to bind values to views. You should use this class to bind values to views that are not directly supported by SimpleAdapter or to change the way binding occurs for views supported by SimpleAdapter.

你可以使用該類(lèi)來(lái)處理SimpleAdapter不直接支持的數(shù)據(jù)；

下面來(lái)看看完整的代碼：

main.xml 中就是一個(gè)ListView ， list_item.xml 是為L(zhǎng)istView中控件提供布局 ，就是一個(gè)ImageView。這兩個(gè)比較簡(jiǎn)單，不貼出代碼

主要代碼 MainActivity.java

package com.yin.listView; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.widget.ImageView; import android.widget.ListView; import android.widget.SimpleAdapter; import android.widget.SimpleAdapter.ViewBinder; public class MainActivity extends Activity { ListView mListView; View mView; public static final String imageUrl = "http://www.google.com//ig/images/weather/mostly_sunny.gif"; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mView = LayoutInflater.from(this).inflate(R.layout.list_item,null); mListView = (ListView) findViewById(R.id.mList); List<HashMap<String,Object>> mListData = getListData(); SimpleAdapter adapter = new SimpleAdapter(this, mListData, R.layout.list_item, new String[]{"icon"}, new int[]{R.id.image}); adapter.setViewBinder(new ViewBinder() { public boolean setViewValue(View view, Object data, String textRepresentation) { //判斷是否為我們要處理的對(duì)象 if(view instanceof ImageView && data instanceof Bitmap){ ImageView iv = (ImageView) view; iv.setImageBitmap((Bitmap) data); return true; }else return false; } }); mListView.setAdapter(adapter); } public List<HashMap<String,Object>> getListData(){ List<HashMap<String,Object>> list = new ArrayList<HashMap<String,Object>>(); HashMap<String,Object> map = null; for(int i=0;i<5;i++){ map = new HashMap<String, Object>(); map.put("icon",getBitmap()); list.add(map); } return list; } public Bitmap getBitmap(){ Bitmap mBitmap = null; try { URL url = new URL(imageUrl); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); InputStream is = conn.getInputStream(); mBitmap = BitmapFactory.decodeStream(is); } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return mBitmap; } }

注意：此例是顯示網(wǎng)絡(luò)圖片 要記得添加權(quán)限

<uses-permission android:name="android.permission.INTERNET">

Android基礎(chǔ)篇之在ListView中顯示網(wǎng)絡(luò)圖片