求解 使用 LruCache缓存 后出现的问题
使用 LruCache缓存 后 第一屏图片加载 不出来 ，来回滑动后 图片才能正常显示 请问这是什么原因呢
是
new ImageLoder().showImageByAsyncTask(viewHolder.ivIcon,url);
替换成成
loder.showImageByAsyncTask(viewHolder.ivIcon,url);
出现的问题么
2 回答
这个是加载图片的代码
package com.example.asynctask2;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import android.annotation.SuppressLint;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.util.LruCache;
import android.widget.ImageView;
@SuppressLint("NewApi")
public class ImageLoder {
private ImageView mImageView;
//图片缓存
private LruCache<String,Bitmap> mcache;
private String mUrl;
public ImageLoder(){
//获取最大可用内存
int maxMemory=(int) Runtime.getRuntime().maxMemory();
int cacheSize=maxMemory/4;
//Log.i("maxMemory",""+cacheSize);
mcache = new LruCache<String, Bitmap>(cacheSize){
//必须重写此方法，来测量Bitmap的大小
@Override
protected int sizeOf(String key, Bitmap value) {
return value.getRowBytes();
}
};
}
/**
* 添加Bitmap到内存缓存
* @param key
* @param bitmap
*/
public void addBitmapToMemoryCache(String key, Bitmap bitmap) {
if (getBitmapFromMemCache(key) == null && bitmap != null) {
mcache.put(key, bitmap);
}
}
/**
* 从内存缓存中获取一个Bitmap
* @param key
* @return
*/
public Bitmap getBitmapFromMemCache(String key) {
return mcache.get(key);
}
Handler handler=new Handler(){
public void handleMessage(android.os.Message msg) {
super.handleMessage(msg);
if(mImageView.getTag().equals(mUrl)){
mImageView.setImageBitmap((Bitmap) msg.obj);
}
};
};
public void showImageByThread(ImageView imageview,final String url){
mImageView=imageview;
mUrl=url;
new Thread(){
public void run() {
super.run();
Bitmap bitmap=getBitmapFromURL(url);
Message msg=Message.obtain();
msg.obj=bitmap;
handler.sendMessage(msg);
}
}.start();
}
/**
* 使用异步任务获取网络图片
* @param imageview
* @param url
*/
public void showImageByAsyncTask(ImageView imageview,final String url){
Bitmap bitmap = getBitmapFromMemCache(url);
if(bitmap==null){
new ImgNetByAsyncTask(imageview,url).execute(url);
}else{
imageview.setImageBitmap(bitmap);
}
}
private class ImgNetByAsyncTask extends AsyncTask<String, Void, Bitmap>{
private ImageView tImageView;
public ImgNetByAsyncTask(ImageView imageview,String url){
tImageView=imageview;
mUrl=url;
}
protected Bitmap doInBackground(String... params) {
String url=params[0];
Bitmap bitmap = getBitmapFromURL(url);
if(bitmap!=null){
addBitmapToMemoryCache(url,bitmap);
}
return bitmap;
}
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
if(tImageView.getTag().equals(mUrl)){
tImageView.setImageBitmap(bitmap);
}
}
}
public Bitmap getBitmapFromURL(String urlString){
Bitmap bitmap;
InputStream is=null;
try {
URL url=new URL(urlString);
HttpURLConnection connection=(HttpURLConnection) url.openConnection();
is=new BufferedInputStream(connection.getInputStream());
bitmap=BitmapFactory.decodeStream(is);
connection.disconnect();
return bitmap;
} catch (java.io.IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
try {
is.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return null;
}
}举报
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