我用的是异步加载图片的方式，并且使用了缓存的方式。
1、这是继承了AsyncTask<String, Void, Bitmap>的MyTask类，用异步加载图片
public class MyTask extends AsyncTask<String, Void, Bitmap> {
private ImageView imageView;
private LruCache<String, Bitmap> lruCache;
/**
* 构造方法，需要把ImageView控件和LruCache对象传进来
*
* @param imageView
* 加载图片到此
* @param lruCache
* 缓存图片的对象
*/
public MyTask(ImageView imageView, LruCache<String, Bitmap> lruCache) {
super();
this.imageView = imageView;
this.lruCache = lruCache;
}
/**
* 调用LruCache的put 方法将图片加入内存缓存中，要给这个图片一个key 方便下次从缓存中取出来
*
* @param key
* @param bitmap
*/
private void addBitmapToMemoryCache(String key, Bitmap bitmap) {
if (getBitmapFromMemoryCache(key) == null) {
lruCache.put(key, bitmap);
}
}
/**
* 调用Lrucache的get 方法从内存缓存中去图片
*
* @param key
* @return
*/
public Bitmap getBitmapFromMemoryCache(String key) {
return lruCache.get(key);
}
@Override
protected Bitmap doInBackground(String... params) {
// TODO Auto-generated method stub
Bitmap bitmap = null;
try {
HttpURLConnection connection = (HttpURLConnection) new URL(
params[0]).openConnection();
connection.setConnectTimeout(10000);
connection.setRequestMethod("GET");
connection.setDoInput(true);
if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
InputStream instr = connection.getInputStream();
bitmap = BitmapFactory.decodeStream(instr);
instr.close();
}
} catch (Exception e) {
e.printStackTrace();
}
addBitmapToMemoryCache(params[0], bitmap);
return bitmap;
}
@Override
protected void onPostExecute(Bitmap result) {
this.imageView.setImageBitmap(result);
}
}
2、这是继承了BaseAdapter的MyAdapter类
public class MyAdapter extends BaseAdapter {
private Context context;
private LayoutInflater inflater;
private List<String> picPath;
private final int maxMemory = (int) Runtime.getRuntime().maxMemory(); // 获取当前应用程序所分配的最大内存
private final int cacheSize = maxMemory / 5; // 只分5分之一来做缓存
private LruCache<String, Bitmap> mlruCache = new LruCache<String, Bitmap>(
cacheSize) {
protected int sizeOf(String key, Bitmap bitmap) { // 复写sizeof()方法
return bitmap.getRowBytes() * bitmap.getHeight() / 1024;// 这是按多少KB来算
};
};
public MyAdapter(Context context, List<String> picPath) {
super();
this.context = context;
this.picPath = picPath;
inflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return picPath.size();
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int arg0, View v, ViewGroup arg2) {
ViewHolder holder = null;
if (v == null) {
holder = new ViewHolder();
v = inflater.inflate(R.layout.item_xml, null);
holder.showiamge = (ImageView) v.findViewById(R.id.showiamge);
v.setTag(holder);
} else {
holder = (ViewHolder) v.getTag();
}
if (v != null) {
loadBitmap(picPath.get(arg0), holder.showiamge);
}
return v;
}
/**
* @param urlStr
* 所需要加载的图片的url。以String形式传进来,可以把这个作为缓存图片的key
* @param image
* ImageView 控件
*/
private void loadBitmap(String urlStr, ImageView image) {
MyTask myTask = new MyTask(image, mlruCache); // 声明一个异步图片加载对象
Bitmap bitmap = myTask.getBitmapFromMemoryCache(urlStr); // 首先从内存缓存中获取图片
if (bitmap != null) {
image.setImageBitmap(bitmap);// 如果缓存中存在这张图片则直接设置给ImageView
} else {
image.setImageResource(R.drawable.ic_launcher);// 否则先设置成默认的图片
myTask.execute(urlStr);// 然后执行异步任务AsycnTask 去网上加载图片
}
}
}
class ViewHolder {
public ImageView showiamge;
}
3、MainActivity类
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = getApplicationContext();
picPath=Utils.addUrl();
listView = (ListView) findViewById(R.id.listView1);
MyAdapter adapter = new MyAdapter(context,picPath);
listView.setAdapter(adapter);
}
4、图片地址的工具类Utils。此图片地址是我电脑上服务器的，运行时需要改成想显示图片的地址。
public class Utils {
/**图片的下载地址
* @return
*/
public static List<String> addUrl() {
List<String> urlList = new ArrayList<String>();
urlList.add("http://192.168.4.101/u=323544003,3655607636&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=337829107,754021853&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=516070125,1299753376&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=805375513,1202624231&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=856554332,2565501919&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=1107822669,2961831310&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=1285718395,2833183433&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=1826201872,3302300664&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=3384623684,3529436072&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=3936768754,2397124933&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/u=4271458677,998187374&fm=21&gp=0.jpg");
urlList.add("http://192.168.4.101/1.jpg");
urlList.add("http://192.168.4.101/2.jpg");
urlList.add("http://192.168.4.101/3.jpg");
urlList.add("http://192.168.4.101/4.jpg");
urlList.add("http://192.168.4.101/5.jpg");
urlList.add("http://192.168.4.101/6.jpg");
urlList.add("http://192.168.4.101/7.jpg");
return urlList;
}
}
本人菜鸟一枚,这是本人第一次网上分享本人的成果,上述代码整合了多位大神的结晶,感觉还不错,如果不对的地方请指示出来。谢谢！
时间： 2024-10-10 16:08:20