通过 JSON 将背景图像填充到列表视图项中的问题
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【中文标题】通过 JSON 将背景图像填充到列表视图项中的问题【英文标题】：Issues populating background image through JSON into list view items 【发布时间】：2014-09-12 16:22:39 【问题描述】：我一直在尝试解决这个问题，但到目前为止我的尝试并不令人满意。
简而言之，我试图为从 JSON 数据生成的每个列表视图数组创建一个背景图像。我已经在 JSON 中设置了背景图像的 url。 JSON 函数已经配置好了，因此我已经能够从在线源将数据填充到应用程序中。
只是为了向您展示一个示例可视化。背景图像的显示类似于以下内容：
http://www.mobile-patterns.com/?q=Hotel+Tonight+feed
但每个背景图像项都将引用它们各自的 JSON 字符串。
我真的坚持这一点。提前致谢。
下面是我的 ListViewAdapter 类
import java.util.ArrayList;
import java.util.HashMap;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
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.RelativeLayout;
import android.widget.TextView;
public class ListViewAdapter extends BaseAdapter
// Declare Variables
Context context;
LayoutInflater inflater;
ArrayList<HashMap<String, String>> data;
ImageLoader imageLoader;
HashMap<String, String> resultp = new HashMap<String, String>();
protected String list_item_bac;
public ListViewAdapter(Context context,
ArrayList<HashMap<String, String>> arraylist)
this.context = context;
data = arraylist;
imageLoader = new ImageLoader(context);
@Override
public int getCount()
return data.size();
@Override
public Object getItem(int position)
return null;
@Override
public long getItemId(int position)
return 0;
public View getView(final int position, View convertView, ViewGroup parent)
// Declare Variables
TextView list_item_name;
TextView country;
TextView list_item_price;
ImageView list_item_bac;
inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View itemView = inflater.inflate(R.layout.listview_item, parent, false);
RelativeLayout rootRelativeLayout=(RelativeLayout)itemView.findViewById(R.id.rootRelativeLayout);
new ImageDownloadTask(rootRelativeLayout,"http://dooba.ca/analytics/ed.php").execute();
//rootRelativeLayout.setBackground(null);
// Get the position
resultp = data.get(position);
// Locate the TextViews in listview_item.xml
list_item_name = (TextView) itemView.findViewById(R.id.list_item_name);
country = (TextView) itemView.findViewById(R.id.country);
list_item_price = (TextView) itemView.findViewById(R.id.list_item_price);
// Locate the ImageView in listview_item.xml
list_item_bac = (ImageView) itemView.findViewById(R.id.list_item_bac);
// Capture position and set results to the TextViews
list_item_name.setText(resultp.get(MainActivity.LIST_ITEM_NAME));
country.setText(resultp.get(MainActivity.COUNTRY));
list_item_price.setText(resultp.get(MainActivity.LIST_ITEM_PRICE));
// Capture position and set results to the ImageView
// Passes flag images URL into ImageLoader.class
imageLoader.DisplayImage(resultp.get(MainActivity.LIST_ITEM_BAC), list_item_bac);
// Capture ListView item click
itemView.setOnClickListener(new OnClickListener()
@Override
public void onClick(View arg0)
// Get the position
resultp = data.get(position);
Intent intent = new Intent(context, SingleItemView.class);
intent.putExtra("list_item_name", resultp.get(MainActivity.LIST_ITEM_NAME));
intent.putExtra("country", resultp.get(MainActivity.COUNTRY));
intent.putExtra("list_item_price",resultp.get(MainActivity.LIST_ITEM_PRICE));
intent.putExtra("list_item_bac", resultp.get(MainActivity.LIST_ITEM_BAC));
// Start SingleItemView Class
context.startActivity(intent);
);
return itemView;
AsyncTask<View,View,View> mytask= new AsyncTask<View,View,View>()
@Override
protected View doInBackground(View... params)
Bitmap img = imageLoader.loadImageSync(list_item_bac);
return null;
;
class ImageDownloadTask extends AsyncTask<View, View, View>
RelativeLayout mrelativelayout;
String downloadUrl;
Bitmap img;
public ImageDownloadTask(RelativeLayout layout,String url)
mrelativelayout=layout;
downloadUrl=url;
@Override
protected View doInBackground(View... params)
// TODO Auto-generated method stub
img = imageLoader.loadImageSync(downloadUrl);
return null;
protected void onPostExecute(Void result)
Drawable d = new BitmapDrawable(context.getResources(), img);
mrelativelayout.setBackground(d);
下面是我的 JSON 函数类
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.util.Log;
public class JSONfunctions
public static JSONObject getJSONfromURL(String url)
InputStream is = null;
String result = "";
JSONObject jArray = null;
// Download JSON data from URL
try
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
catch (Exception e)
Log.e("log_tag", "Error in http connection " + e.toString());
// Convert response to string
try
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
sb.append(line + "\n");
is.close();
result = sb.toString();
catch (Exception e)
Log.e("log_tag", "Error converting result " + e.toString());
try
jArray = new JSONObject(result);
catch (JSONException e)
Log.e("log_tag", "Error parsing data " + e.toString());
return jArray;
listview布局xml如下
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:paddingLeft="20dp"
android:paddingRight="20dp"
android:paddingTop="7dp"
android:id="@+id/rootRelativeLayout"
android:paddingBottom="7dp"
android:orientation="vertical" >
<TextView
android:id="@+id/ranklabel"
android:layout_
android:layout_
android:textColor="#F0F0F0"/>
<TextView
android:id="@+id/list_item_name"
android:layout_
android:layout_
android:textColor="#F0F0F0"/>
<TextView
android:id="@+id/countrylabel"
android:layout_
android:layout_
android:layout_below="@+id/ranklabel"
android:text="@string/countrylabel"
android:textColor="#F0F0F0"/>
<TextView
android:id="@+id/country"
android:layout_
android:layout_
android:layout_below="@+id/list_item_name"
android:layout_toRightOf="@+id/countrylabel"
android:textColor="#F0F0F0"/>
<TextView
android:id="@+id/populationlabel"
android:layout_
android:layout_
android:layout_below="@+id/countrylabel"
android:text="@string/populationlabel"
android:textColor="#F0F0F0"/>
<TextView
android:id="@+id/list_item_price"
android:layout_
android:layout_
android:layout_below="@+id/country"
android:shadowColor="#000000"
android:shadowDx="-2"
android:shadowDy="2"
android:shadowRadius="0.01"
android:textColor="#f2f2f2"/>
<ImageView
android:id="@+id/list_item_bac"
android:layout_alignParentTop="true"
android:layout_
android:layout_
android:layout_margin="0dp"
android:background="#000000"
android:alpha="0.8" />
</RelativeLayout>
如果您需要任何其他可以帮助您帮助我的信息，请告诉我。 任何帮助将不胜感激
单项点击更新代码
import java.util.ArrayList;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.android.volley.Request.Method;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.dooba.beta.Events_List;
import com.dooba.beta.R;
import com.dooba.beta.R.id;
import com.dooba.beta.R.layout;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.ListAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class EventsActivity extends Activity
private static final String URL_WEB_SERVICE = "http://dooba.ca/analytics/ed.php";
private GridView gvAnuncios;
private ArrayList<Events_List> anuncios;
private ArrayList<Events_List> items;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.layout_anuncios);
gvAnuncios = (GridView) findViewById(R.id.gridview_anuncios);
anuncios = new ArrayList<Events_List>();
//download JSON
descargarAnuncios();
//add interface ItemClickListener
public interface ItemClickListener
listview.setOnItemClickListener(new OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
Intent intent = new Intent(EventsActivity.this,EventSingleItemActivity.class);
intent.putExtra("id_item", id);//this is id of the item that you said it. for example id:5544323 from your JSON web service
intent.putExtra("position", position); //order position in listview 0-1-2-3...
startActivity(intent); //start Activity
//catch in the second activity values ??that you use to
long id_item = getIntent().getExtras().getLong("id_item");
int position = getIntent().getExtras().getInt("id_item");
//sorry, my english is low :)
//remember add reference to id of the item from your json we service in adapter
public long getItemId(int position)
return items.get(position).id; //<--your id from json
public void descargarAnuncios()
RequestQueue volley = Volley.newRequestQueue(this);
JsonObjectRequest json = new JsonObjectRequest(Method.GET, URL_WEB_SERVICE, null, ResponseListener(), ErrorListener());
volley.add(json);
private Response.Listener<JSONObject> ResponseListener()
return new Response.Listener<JSONObject>()
@Override
public void onResponse(JSONObject response)
try
//your JSON Array
JSONArray array = response.getJSONArray("list_item");
for(int i = 0; i < array.length(); i++)
//add object anuncio to arraylist anuncios
anuncios.add(convertirAnuncio(array.getJSONObject(i)));
catch (JSONException e)
e.printStackTrace();
gvAnuncios.setAdapter(new AdapterEvents(getApplicationContext(),anuncios));
;
;
private Response.ErrorListener ErrorListener()
return new Response.ErrorListener()
@Override
public void onErrorResponse(VolleyError error)
;
//object JSON
private final Events_List convertirAnuncio(JSONObject obj) throws JSONException
long id = obj.getLong("id"); //id
String list_item_name = obj.getString("list_item_name"); //title item
String list_item_description = obj.getString("list_item_description");
String list_item_price = obj.getString("list_item_price");
Uri uri = Uri.parse(obj.getString("list_item_bac")); //url image "http//:google.image.....jpg"
return new Events_List(id,list_item_name,list_item_description,list_item_price, uri);
【问题讨论】：
【参考方案1】：我做了与你类似的事情，并使用 Volley 和 Picasso 库解决了问题。这是我的代码，希望能帮到你。我用的是gridview，差不多。 https://mega.co.nz/#!3Z5SSTCR!PxG2SmPTFYwqY6RDfpU1RK8tS6hN9nBovGF8lCtUVoc
【讨论】：
非常感谢。它帮助很大。我现在正在研究“单项点击”。也就是说，当用户单击列表项时，它会为他们带来一个相应的活动，该活动会填充有关它的更多信息。 好的。检查这个...mega.co.nz/… 谢谢兄弟。您的支持令人难以置信。作为建议，我们可以尝试使用内存和文件等缓存来提高速度和效率，从而使用户体验更加无缝。以下链接提供了更多信息。 androidbegin.com/tutorial/…单品编码，请提供。我尝试添加它，但遇到了一些我难以修复的问题。您可以在我更新的帖子中查看带有单个项目的更新代码 您好，我对您的代码进行了改编，我在 android 4.4.2 上工作，仅导入和 Volley Picasso 库，然后运行。如有任何问题，我们在这里:)。注意：减小图像的大小，因为它会导致内存不足。 mega.co.nz/… 谢谢兄弟，你的帮助很大不能上传。至于您提出的新代码，我似乎更喜欢您以前的代码。问题在于根据您之前的建议添加单个项目，并将“添加接口 ItemClickListener”添加到活动中。我在我的初始帖子中添加了更新下的活动代码。如果单个项目中有一个按钮可以在单击时将用户带到新活动，那就太好了。以上是关于通过 JSON 将背景图像填充到列表视图项中的问题的主要内容，如果未能解决你的问题，请参考以下文章
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