好吧，我用这个项目作为我项目的起点： https://github.com/thest1/LazyList/
而不是他的LazyAdapter，我使用了我制作的一个，以下：
public class CardAdapter extends ArrayAdapter<Card> {
private Card[] cards;
private Context context;
private LayoutInflater mInflater;
public ImageLoader imageLoader;
public CardAdapter (Context context, int textViewResourcesId, Card[] cards)
{
super(context, textViewResourcesId, cards);
this.cards = cards;
this.context = context;
mInflater = LayoutInflater.from(context);
}
private static class ViewHolder {
public ImageView iconView;
public TextView nameTextView;
public TextView descText;
public TextView manaText;
public TextView atkdef;
public TextView edicao;
public TextView tipo;
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.listrow, parent, false);
TextView nameTextView = (TextView) convertView
.findViewById(R.id.Nome);
TextView descText = (TextView) convertView
.findViewById(R.id.descricao);
TextView manaText = (TextView) convertView
.findViewById(R.id.mana);
TextView atkdef = (TextView) convertView
.findViewById(R.id.atkdef);
TextView edicao = (TextView) convertView
.findViewById(R.id.edicao);
TextView tipo = (TextView) convertView
.findViewById(R.id.tipo);
ImageView iconView = (ImageView) convertView
.findViewById(R.id.imageView1);
holder = new ViewHolder();
holder.nameTextView = nameTextView;
holder.descText = descText;
holder.manaText = manaText;
holder.atkdef = atkdef;
holder.edicao = edicao;
holder.tipo = tipo;
holder.iconView = iconView;
holder.iconView.setTag(cards[position].URL);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.nameTextView.setText(cards[position].name); holder.descText.setText(setSpanOnText(cards[position].descricao),BufferType.SPANNABLE);
holder.manaText.setText(setSpanOnManaText(cards[position].mana), BufferType.SPANNABLE);
if (cards[position].tipo.toLowerCase().contains("creature"))
holder.atkdef.setText(cards[position].power + "/" + cards[position].toughness);
else
holder.atkdef.setText("");
holder.edicao.setText("Edition: " + cards[position].edicao);
holder.tipo.setText(cards[position].tipo);
holder.iconView.setTag(cards[position].URL);
imageLoader.DisplayImage(cards[position].URL, holder.iconView);
return convertView;
}
}
它运作良好，直到我添加“imageLoader.DisplayImage（cards [position] .URL，holder.iconView）;”这是懒惰的负载部分，当我尝试访问列表视图时，它开始崩溃，有人有想法吗？我在其他项目的ImageLoader / FileCache / MemoryCache / Utils中没有改变...
感谢您的建议！
答案 0 :(得分：0)
之前我使用过这个懒惰加载程序代码，并且它正在尝试访问您的SD卡，因此请确保在清单中设置正确的权限。
此外，您不应该访问ListView，只需访问与标记对应的ImageView。你确定你做得对吗？您可能需要使用此类发布代码。
在ListView中使用它的正确方法是：
imageView.setTag(image_url);
imageLoader.DisplayImage(image_url, imageView);
。
答案 1 :(得分：0)
package com.jaapp;
import java.util.ArrayList;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.jaapp.application.JaappApplication;
import com.jaapp.db.Jaappdb;
import com.jaapp.dto.SubtypeDto;
import com.jaapp.lazyloader.ImageLoader;
public class SubTypeActivity extends Activity {
ArrayList<SubtypeDto> arrylistsubtype = new ArrayList<SubtypeDto>();
ListView list;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.subtype);
new subtypeAsyncTask().execute();
}
public class subtypeAsyncTask extends AsyncTask<Void, Void, Void> {
private ProgressDialog progrssdilaog;
@Override
protected void onPreExecute() {
progrssdilaog = ProgressDialog.show(SubTypeActivity.this,
"Please wait", "Loading Data ...", true);
}
@Override
protected Void doInBackground(Void... params) {
arrylistsubtype = Jaappdb.getSubtypeDtos();
return null;
}
@Override
protected void onPostExecute(Void result) {
progrssdilaog.dismiss();
list = (ListView) findViewById(R.id.list);
list.setAdapter(new Listadatper(SubTypeActivity.this,
arrylistsubtype));
}
}
public class Listadatper extends BaseAdapter {
private Activity activity;
public ImageLoader imageLoader;
ArrayList<SubtypeDto> mlist;
public int[] selected;
public int countcolor = 0;
public int i = 0;
public String[] Colorname = { "#FFFF00", "#ACCC00" };
public Listadatper(SubTypeActivity secondActivity,
ArrayList<SubtypeDto> arrylistsubtype) {
this.activity = secondActivity;
mlist = arrylistsubtype;
selected = new int[mlist.size()];
for (int i = 0; i < mlist.size(); i++) {
selected[i] = 0;
}
}
public View getView(final int position, View convertView,
ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View gridView;
gridView = inflater.inflate(R.layout.list_row, null);
TextView txt_name = (TextView) gridView
.findViewById(R.id.txt_entrepreneur);
ImageView img_icon = (ImageView) gridView
.findViewById(R.id.img_entrepreneur);
txt_name.setText(mlist.get(position).getName());
imageLoader = new ImageLoader(activity.getApplicationContext());
imageLoader.DisplayImage(getString(R.string.imagelink) + mlist.get(position).getLogo(), activity, img_icon);
if(position % 2 == 0) {
gridView.setBackgroundColor(Color.parseColor(Colorname[0]));
} else {
gridView.setBackgroundColor(Color.parseColor(Colorname[1]));
}
gridView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(SubTypeActivity.this,
SubOptionTypeActivity.class);
JaappApplication.subtypeid = mlist.get(position).getId();
startActivity(i);
}
});
return gridView;
}
@Override
public int getCount() {
return mlist.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
}
}
------------------------------------------------------------------------------------------
package com.jaapp.lazyloader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.HashMap;
import java.util.Stack;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;
import com.jaapp.R;
public class ImageLoader {
private HashMap<String, Bitmap> cache=new HashMap<String, Bitmap>();
private File cacheDir;
public ImageLoader(Context context){
photoLoaderThread.setPriority(Thread.NORM_PRIORITY-1);
if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"LazyList");
else
cacheDir=context.getCacheDir();
if(!cacheDir.exists())
cacheDir.mkdirs();
}
final int stub_id=R.drawable.stub;
public void DisplayImage(String url, Activity activity, ImageView imageView)
{
if(cache.containsKey(url))
imageView.setImageBitmap(cache.get(url));
else
{
queuePhoto(url, activity, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, Activity activity, ImageView imageView)
{
photosQueue.Clean(imageView);
PhotoToLoad p=new PhotoToLoad(url, imageView);
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.push(p);
photosQueue.photosToLoad.notifyAll();
}
if(photoLoaderThread.getState()==Thread.State.NEW)
photoLoaderThread.start();
}
private Bitmap getBitmap(String url)
{
String filename=String.valueOf(url.hashCode());
File f=new File(cacheDir, filename);
//from SD cache
Bitmap b = decodeFile(f);
if(b!=null)
return b;
//from web
try {
Bitmap bitmap=null;
InputStream is=new URL(url).openStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex){
ex.printStackTrace();
return null;
}
}
//decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f){
try {
//decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f),null,o);
//Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE=70;
int width_tmp=o.outWidth, height_tmp=o.outHeight;
int scale=1;
while(true){
if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
break;
width_tmp/=2;
height_tmp/=2;
scale++;
}
//decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize=scale;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {}
return null;
}
//Task for the queue
private class PhotoToLoad
{
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i){
url=u;
imageView=i;
}
}
PhotosQueue photosQueue=new PhotosQueue();
public void stopThread()
{
photoLoaderThread.interrupt();
}
//stores list of photos to download
class PhotosQueue
{
private Stack<PhotoToLoad> photosToLoad=new Stack<PhotoToLoad>();
//removes all instances of this ImageView
public void Clean(ImageView image)
{
for(int j=0 ;j<photosToLoad.size();){
if(photosToLoad.get(j).imageView==image)
photosToLoad.remove(j);
else
++j;
}
}
}
class PhotosLoader extends Thread {
public void run() {
try {
while(true)
{
//thread waits until there are any images to load in the queue
if(photosQueue.photosToLoad.size()==0)
synchronized(photosQueue.photosToLoad){
photosQueue.photosToLoad.wait();
}
if(photosQueue.photosToLoad.size()!=0)
{
PhotoToLoad photoToLoad;
synchronized(photosQueue.photosToLoad){
photoToLoad=photosQueue.photosToLoad.pop();
}
Bitmap bmp=getBitmap(photoToLoad.url);
cache.put(photoToLoad.url, bmp);
//if(((String)photoToLoad.imageView.getTag()).equals(photoToLoad.url)){
BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad.imageView);
Activity a=(Activity)photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
// }
}
if(Thread.interrupted())
break;
}
} catch (InterruptedException e) {
//allow thread to exit
}
}
}
PhotosLoader photoLoaderThread=new PhotosLoader();
//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
Bitmap bitmap;
ImageView imageView;
public BitmapDisplayer(Bitmap b, ImageView i){bitmap=b;imageView=i;}
public void run()
{
if(bitmap!=null)
imageView.setImageBitmap(bitmap);
else
imageView.setImageResource(stub_id);
}
}
public void clearCache() {
//clear memory cache
cache.clear();
//clear SD cache
File[] files=cacheDir.listFiles();
for(File f:files)
f.delete();
}
}
------------------------------------------------------------------------------------------
package com.jaapp.lazyloader;
import java.io.InputStream;
import java.io.OutputStream;
public class Utils {
public static void CopyStream(InputStream is, OutputStream os)
{
final int buffer_size=1024;
try
{
byte[] bytes=new byte[buffer_size];
for(;;)
{
int count=is.read(bytes, 0, buffer_size);
if(count==-1)
break;
os.write(bytes, 0, count);
}
}
catch(Exception ex){}
}
}