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我开发了一个联系人应用程序。它可以完成普通联系人应用程序应该做的一切。总有改善的机会。我注意到在Android模拟器中，加载联系人图像是在用户定居时开始的，他已经将联系人列表滚动到有可能与他正在寻找的联系人的机会的区域。所以，我试图在我的应用程序副本上实现相同的功能。我已经实现了它。它的运行非常缓慢。正如我所假设的那样，我认为即使应用程序检索到导致严重滞后的图像，应用程序也会多次运行该线程。我知道ASync任务，但出于好奇，并检查是否可以完成，我不希望在这里实现它。以下是MainActivity的源代码。缓慢的应用程序性能
package com.example.contact;
import java.io.InputStream;
import java.util.ArrayList;
import android.net.Uri;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.provider.ContactsContract.Contacts;
import android.app.ListActivity;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
public class MainActivity extends ListActivity {
ListView listview;
private boolean mPaused;
private MyAdapter mAdapter;
private View view;
private boolean running = false;
final private ArrayList<String> con_ids = new ArrayList<String>();
private Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
listview = getListView();
context = this;
Cursor c = getContentResolver().query(ContactsContract.Contacts.CONTENT_URI,
null,
null,
null,
ContactsContract.Contacts.DISPLAY_NAME+" ASC");
if(c!=null)
{
for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
con_ids.add(c.getString(c.getColumnIndex(ContactsContract.Contacts._ID)));
}
}
mAdapter = new MyAdapter(this, android.R.layout.simple_list_item_1, con_ids);
listview.setAdapter(mAdapter);
listview.setOnScrollListener(makeScrollListener());
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
public void setEnabled(boolean enabled) {
mPaused = !enabled;
}
private AbsListView.OnScrollListener makeScrollListener() {
return new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState) {
setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
running = false;
}
@Override
public void onScroll(AbsListView absListView, int i, int i1, int i2) {
String log = "";
Log.d(log, "Scroll First Item" + i);
Log.d(log, ""+ listview.getChildCount());
final int want = i;
running = true;
runOnUiThread(new Thread(new Runnable() {
int totalChild = listview.getChildCount();
int first = listview.getFirstVisiblePosition() - listview.getHeaderViewsCount();
int toRetrieve = want-first;
int id;
long con_id;
Bitmap thumbnail;
final ListView list = listview;
@Override
public void run() {
// TODO Auto-generated method stub
while(running)
{
if(!(toRetrieve<0||toRetrieve>=totalChild))
{
id = want+toRetrieve;
con_id = Long.valueOf(con_ids.get(id));
Uri ContactUri = ContentUris.withAppendedId(Contacts.CONTENT_URI, con_id);
InputStream stream = ContactsContract.Contacts.openContactPhotoInputStream(context.getContentResolver(), ContactUri);
thumbnail = BitmapFactory.decodeStream(stream);
if(thumbnail == null)
{
toRetrieve++;
continue;
}
else
{
View view = list.getChildAt(toRetrieve);
if(view == null)
{
toRetrieve++;
continue;
}
else
{
ImageView iamge = (ImageView) view.findViewById(R.id.contact_iamge);
iamge.setImageBitmap(thumbnail);
}
toRetrieve++;
}
}
else
{
running = false;
}
}
}
}));
}
};
}
}
代码MyAdapter，
package com.example.contact;
import java.util.ArrayList;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.provider.ContactsContract;
import android.provider.ContactsContract.Contacts;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView.FindListener;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
public class MyAdapter extends ArrayAdapter<String> {
private Context context;
private ListView listview;
private ArrayList<String> ids;
private LayoutInflater infl;
private String displayname;
private String maindetail;
private SimplifiedContact contact;
private Drawable drawable;
public MyAdapter(Context context, int ResourceId, ArrayList<String> list)
{
super(context, ResourceId, list);
this.context = context;
ids = list;
infl = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
drawable = context.getResources().getDrawable(R.drawable.person);
}
static class ViewHolder
{
public ImageView image;
public TextView display_name;
public TextView main_detail;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
contact = new SimplifiedContact(context, Long.valueOf(ids.get(position)));
if(row == null)
{
row = infl.inflate(R.layout.single_cell, parent, false);
ViewHolder viewHolder = new ViewHolder();
viewHolder.display_name =(TextView) row.findViewById(R.id.disp_name);
viewHolder.main_detail = (TextView) row.findViewById(R.id.main_detail);
viewHolder.image = (ImageView)row.findViewById(R.id.contact_iamge);
row.setTag(viewHolder);
}
ViewHolder holder = (ViewHolder) row.getTag();
holder.display_name.setText(contact.getDisplayName());
holder.main_detail.setText(contact.getMainDetail());
holder.image.setBackgroundDrawable(drawable);
return row;
}
}
，我想知道，如何滞后可以降低。提前致谢。
前runOnUiThread产生线程（）。我使用了普通的线程过程，导致了一个异常，即最初创建视图的主线程可能是唯一修改它的异常。我搜索了解决方案并了解到为了让事情变得更好，我必须在UI线程上运行线程。 – Paras 2013-03-16 22:20:25
那么，我已经在我的应用程序中实现了ASync任务。这只是我不想这样做。所以，基本上，在这个问题中，我是否需要中止onScroll加载概念？ – Paras 2013-03-16 22:50:05