Android同时使用cardview图像加载非常懒惰
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【中文标题】Android同时使用cardview图像加载非常懒惰【英文标题】：Android while using cardview image is loading very lazy 【发布时间】：2016-02-21 03:20:54 【问题描述】：我正在从数据库中将图片（大小小于约 3MB）加载到 Cardview 中，但它在 Listviewstview 中是错误的。
这些图片的加载和浏览太慢了。
有什么方法可以缩小这些图片以加快速度，有时会在其他卡片视图上显示 [重复] 图像？
卡片视图 xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:orientation="horizontal">
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="@+id/cv"
android:layout_
android:layout_
android:alpha="1"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
card_view:cardBackgroundColor="#FFFFFF"
card_view:cardCornerRadius="10dp">
<RelativeLayout
android:id="@+id/r1"
android:layout_
android:layout_>
<ImageView
android:id="@+id/img_product"
android:layout_
android:layout_
android:layout_marginLeft="@dimen/activity_vertical_margin"
android:layout_marginTop="20dp" />
<TextView
android:id="@+id/product_name"
android:layout_
android:layout_
android:layout_alignTop="@+id/img_product"
android:layout_toEndOf="@+id/img_product"
android:layout_toRightOf="@+id/img_product"
android:inputType="textMultiLine"
android:text="Parvana Fancy Necklace Set"
android:textSize="18dp"
android:textStyle="bold" />
<TextView
android:id="@+id/txt_total"
android:layout_
android:layout_
android:layout_alignBottom="@+id/img_product"
android:layout_toEndOf="@+id/img_product"
android:layout_toRightOf="@+id/img_product"
android:text="RS.234"
android:textSize="20dp"
android:textStyle="bold" />
<Button
android:id="@+id/btn_remove"
android:layout_
android:layout_
android:background="@drawable/wishlistddelete_selector"
android:drawableLeft="@drawable/delete_icon"
android:layout_alignTop="@+id/txt_total"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</RelativeLayout>
列表视图 xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:background="@drawable/home_bground">
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:orientation="vertical">
<RelativeLayout
android:id="@+id/topbar1"
android:layout_
android:layout_
android:background="@drawable/top">
<ImageView
android:id="@+id/btn_hme"
android:layout_
android:layout_
android:layout_marginLeft="10dp"
android:src="@drawable/home_icon" />
<TextView
android:id="@+id/txt_pro_name"
android:layout_
android:layout_
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:gravity="center_horizontal"
android:text="Shopping Cart"
android:textColor="#ffffff"
android:textSize="18dp"
android:textStyle="bold" />
</RelativeLayout>
<ListView
android:id="@+id/list_item"
android:layout_
android:layout_
android:layout_below="@id/topbar1"
android:animationCache="false"
android:dividerHeight="0dp"
android:listSelector="#00000000"
android:scrollingCache="false"
android:smoothScrollbar="true" />
</RelativeLayout>
</RelativeLayout>
使用 sqllite 访问数据库中的数据
public class Wishlist extends Activity
Button checkout;
ListView ListCart;
String name, cusid, ffname, llname, phone, fax, password, email;
String[] qu, s;
int[] g;
int k = 0;
String cost;
ProgressDialog pDialog = null;
List<CartProducts> product_list;
Context ctx;
Integer pos = 0, total = 0, q = 0, gtot = 0, total1 = 0, sum = 0;
SQLiteDatabase FavData;
private Context context;
Integer i;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_modifywishlist);
Intent page1 = getIntent();
cusid = page1.getStringExtra("cus_id");
ffname = page1.getStringExtra("fname");
llname = page1.getStringExtra("lname");
phone = page1.getStringExtra("ph");
fax = page1.getStringExtra("fax");
password = page1.getStringExtra("password");
email = page1.getStringExtra("email");
ListCart = (ListView) findViewById(R.id.list_item);
ListCart.setScrollingCacheEnabled(false);
Intent page2 = getIntent();
i = page2.getIntExtra("kvalue",1);
pDialog = new ProgressDialog(this);
ctx = this;
FavData = Wishlist.this.openOrCreateDatabase("SHOPPING_CARTFAV", MODE_PRIVATE, null);
FavData.execSQL("CREATE TABLE IF NOT EXISTS fav_items(product_id varchar, name varchar, price varchar, quantity integer, model varchar, image varchar, manufacturer varchar )");
ArrayList<CartProducts> myList = new ArrayList<CartProducts>();
Cursor crsr = FavData.rawQuery("SELECT * FROM fav_items", null);
final String[] productID = new String[crsr.getCount()];
final String[] ProductName = new String[crsr.getCount()];
final String[] ProductPrice = new String[crsr.getCount()];
final String[] ProductQuantity = new String[crsr.getCount()];
final String[] ProductModel = new String[crsr.getCount()];
final String[] ProductImage = new String[crsr.getCount()];
final String[] ProductManufacturer = new String[crsr.getCount()];
int j = 0;
while (crsr.moveToNext())
String id = crsr.getString(crsr.getColumnIndex("product_id"));
productID[j] = id;//product_id,name,price,quantity,model,image,manufacturer
name = crsr.getString(crsr.getColumnIndex("name"));
ProductName[j] = name;
String price = crsr.getString(crsr.getColumnIndex("price"));
ProductPrice[j] = price;
String s = ProductPrice[j].toString();
s = s.replace(",", "");
String[] parts = s.split("\\."); // escape .
String part1 = parts[0];
String part2 = parts[1];
part1 = part1.replace("₹", "");
total = Integer.parseInt(part1); // Toast.makeText(Table.this, part1, Toast.LENGTH_SHORT).show();
String qnty = crsr.getString(crsr.getColumnIndex("quantity"));
ProductQuantity[j] = qnty;
String s2 = ProductQuantity[j].toString();
total1 = Integer.parseInt(s2);
sum = total * total1;
String model = crsr.getString(crsr.getColumnIndex("model"));
ProductModel[j] = model;
String image = crsr.getString(crsr.getColumnIndex("image"));
ProductImage[j] = image;
String manufacturer = crsr.getString(crsr.getColumnIndex("manufacturer"));
ProductManufacturer[j] = manufacturer;
myList.add(new CartProducts(productID[j], ProductName[j], ProductPrice[j], ProductQuantity[j], ProductModel[j], ProductImage[j], ProductManufacturer[j]));
gtot = gtot + sum;
j++;
ListCart.setAdapter(new Wishlist_Listadapter(ctx, R.layout.activity_wishlist_cartrow, myList));
String s1 = ProductPrice.toString();
适配器类
public class Wishlist_Listadapter extends ArrayAdapter<CartProducts>
Bitmap bitmap;
ImageView img;
String urll, name,totalps;
SQLiteDatabase FavData;
Integer total = 0, quanty = 1, grandtot = 0, i = 0;
String it;
Button addbtn, minbtn;
EditText editqu;
int total1 = 0, quantity=0, fulltotal = 0, sum;
SQLiteOpenHelper dbhelper;
Wishlist_Listadapter cart = Wishlist_Listadapter.this;
private int resource;
private LayoutInflater inflater;
private Context context;
int count=1 ;
public Wishlist_Listadapter(Context ctx, int resourceId, List<CartProducts> objects)
super(ctx, resourceId, objects);
resource = resourceId;
inflater = LayoutInflater.from(ctx);
context = ctx;
public View getView(int position, View convertView, ViewGroup parent)
/* create a new view of my layout and inflate it in the row */
convertView = (RelativeLayout) inflater.inflate(resource, null);
final ViewHolder viewholder;
viewholder = new ViewHolder();
final CartProducts banqt = getItem(position);
totalps=(banqt.getPrice());
String s = totalps.toString();
s = s.replace(",", "");
String[] parts = s.split("\\."); // escape .
String part1 = parts[0];
String part2 = parts[1];
part1 = part1.replace("₹", "");// Toast.makeText(getContext(), part1, Toast.LENGTH_LONG).show();
total = Integer.parseInt(part1);
quanty = Integer.parseInt(banqt.getQuantity());
grandtot = total *quanty;
viewholder.total = (TextView) convertView.findViewById(R.id.txt_total);
viewholder.total.setText(String.valueOf(grandtot));
Button delet = (Button) convertView.findViewById(R.id.btn_remove);
delet.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
/*delete function*/
it = banqt.getProduct_id();
FavData = context.openOrCreateDatabase("SHOPPING_CARTFAV", context.MODE_PRIVATE, null);
FavData.execSQL("DELETE FROM fav_items WHERE product_id=" + it + ";");
Intent intent = ((Wishlist) context).getIntent();
((Wishlist) context).finish();
context.startActivity(intent);
);
viewholder.txtName = (TextView) convertView.findViewById(R.id.product_name);
viewholder.txtName.setText(banqt.getName());
img = (ImageView) convertView.findViewById(R.id.img_product);
urll = banqt.getImage().toString();
urll = urll.replaceAll(" ", "%20");// Toast.makeText(getContext(),urll,Toast.LENGTH_LONG).show();
new LoadImage().execute(urll);
return convertView;
static class ViewHolder
TextView txtName;
TextView total;
EditText editqu;
TextView txtprice;
private class LoadImage extends AsyncTask<String, String, Bitmap>
@Override
protected void onPreExecute()
super.onPreExecute();
protected Bitmap doInBackground(String... args)
try
bitmap = BitmapFactory.decodeStream((InputStream) new URL(args[0]).getContent());
catch (Exception e)
e.printStackTrace();
return bitmap;
protected void onPostExecute(Bitmap image)
if (image != null)
img.setImageBitmap(image);
// pDialog.dismiss();
else
// pDialog.dismiss();
Toast.makeText(getContext(), "Image Does Not exist or Network Error", Toast.LENGTH_SHORT).show();
【问题讨论】：
使用任何图片库（Picasso、通用 Imageloader、Glide）..它们维护缓存并使用图片缩略图 不使用任何库@VishalGaur 因此，您可以自己创建图像缩略图并维护缓存... 我无法理解。@VishalGaur。我们正在从数据库中调用图像，例如 this link we get 使用 json 只需存储在 sqllite 中，然后从中检索 当您下载图像时，您应该将该图像保留在缓存中一小段时间，以便您可以再次使用它，并且您应该使用缩略图，因为您下载的图像分辨率更高，尺寸更大所以缩略图的尺寸很小 【参考方案1】：尝试缩放bitmap 以降低其实际分辨率，我使用以下代码来减小bitmap 的大小。
int nh = (int) (bitmap.getHeight() * (512.0 / bitmap.getWidth()));
Bitmap scaled = Bitmap.createScaledBitmap(bitmap, 512, nh, true);
对于您的情况，将以下代码添加到您的适配器类 AsyncTask 的 doInBackground 方法中
try
bitmap = BitmapFactory.decodeStream((InputStream) new URL(args[0]).getContent());
int nh = (int) (bitmap.getHeight() * (512.0 / bitmap.getWidth()));
Bitmap scaled = Bitmap.createScaledBitmap(bitmap, 512, nh, true);
catch (Exception e)
e.printStackTrace();
return scaled;
返回缩放位图而不是原始位图。
【讨论】：
在我粘贴此代码的适配器类中。感谢重播 你是在问你应该把这段代码粘贴到你的适配器类的什么地方吗？ 尝试在try-catch方法之外声明scaled
我认为 asynctask 是导致延迟的原因，应该删除它并使用第三方库，例如 glide 或 universal image loader
github.com/nostra13/Android-Universal-Image-Loader，你只需要这个代码来设置你的位图，imageLoader.displayImage(urll , img);以上是关于Android同时使用cardview图像加载非常懒惰的主要内容，如果未能解决你的问题，请参考以下文章
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