java - 带有自定义适配器的 ListView 图像和文本

Question

我创建了一个 ListView 来从 PHP 服务器加载图像和文本。我编写的代码运行良好，没有错误，但我的 ListView 是空白的，不显示任何图像或文本。

LazyAdapter.java

package mygp.gptrade.imageListAdapter;

import java.util.ArrayList;
import java.util.HashMap;


import mygp.gptrade.AllProductActivity;

import mygp.gptrade.R;
import mygp.gptrade.image.ImageLoader;

import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;


public class LazyAdapter extends BaseAdapter {

private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public ImageLoader imageLoader;

public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
    activity = a;
    data=d;
    inflater =     (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    imageLoader=new ImageLoader(activity.getApplicationContext());
}


@Override
public int getCount() {
    return data.size();
}

@Override
public Object getItem(int position) {
     return position;
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View vi=convertView;
    if(convertView==null)
        vi = inflater.inflate(R.layout.list_item, null);

    TextView pid = (TextView)vi.findViewById(R.id.pid);
    TextView itemname = (TextView)vi.findViewById(R.id.name);
    TextView price = (TextView)vi.findViewById(R.id.price);
    ImageView thumb_image = (ImageView)vi.findViewById(R.id.imageView1); //

    HashMap<String, String> song = new HashMap<String, String>();
    song = data.get(position);

    pid.setText(song.get(AllProductActivity.TAG_PID));
    itemname.setText(song.get(AllProductActivity.TAG_NAME));
    price.setText(song.get(AllProductActivity.TAG_PRICE));
    imageLoader.DisplayImage(song.get(AllProductActivity.TAG_PATH),  thumb_image); //
    return vi;
}

}

AllProductActivity.java

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import mygp.gptrade.imageListAdapter.LazyAdapter;

import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class AllProductActivity extends Activity {

// Progress Dialog
private ProgressDialog pDialog;

// Creating JSON Parser object
JSONParser2 jParser = new JSONParser2();

ArrayList<HashMap<String, String>> productsList;

ListView list;
LazyAdapter adapter;


// url to get all products list
private static String url_all_products = "http://gemini888.tk/test4/android_connect/get_all_products.php";

// JSON Node names
public static final String TAG_SUCCESS = "success";
public static final String TAG_PRODUCTS = "products";
public static final String TAG_PID = "uid";
public static final String TAG_NAME = "itemname";
public static final String TAG_PRICE = "price";
public static final String TAG_PATH = "path";

// products JSONArray
JSONArray products = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.all_products);

    list = (ListView)findViewById(android.R.id.list);

    //testing
    if (android.os.Build.VERSION.SDK_INT > 9)
    {
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
    StrictMode.setThreadPolicy(policy);
    }

    // Hashmap for ListView
    productsList = new ArrayList<HashMap<String, String>>();

    // Loading products in Background Thread
    new LoadAllProducts().execute();


    // on seleting single product
    // launching Edit Product Screen
    list.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            // getting values from selected ListItem
            String pid = ((TextView) view.findViewById(R.id.pid)).getText()
                    .toString();

            // Starting new intent
            Intent in = new Intent(getApplicationContext(),
                    EditProductActivity.class);
            // sending pid to next activity
            in.putExtra(TAG_PID, pid);

            // starting new activity and expecting some response back
            startActivityForResult(in, 100);
        }
    });

}

// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // if result code 100
    if (resultCode == 100) {
        // if result code 100 is received
        // means user edited/deleted product
        // reload this screen again
        Intent intent = getIntent();
        finish();
        startActivity(intent);
    }

}

/**
 * Background Async Task to Load all product by making HTTP Request
 * */
class LoadAllProducts extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(AllProductActivity.this);
        pDialog.setMessage("Loading products. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

        // Check your log cat for JSON reponse
        Log.d("All Products: ", json.toString());

        try {
            // Checking for SUCCESS TAG
            int success = json.getInt(TAG_SUCCESS);

            if (success == 1) {
                // products found
                // Getting Array of Products
                products = json.getJSONArray(TAG_PRODUCTS);

                // looping through All Products
                for (int i = 0; i < products.length(); i++) {
                    JSONObject c = products.getJSONObject(i);

                    // Storing each json item in variable
                    String id = c.getString(TAG_PID);
                    String iname = c.getString(TAG_NAME);
                    String price = c.getString(TAG_PRICE);
                    String path = c.getString(TAG_PATH);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    map.put(TAG_PID, id);
                    map.put(TAG_NAME, iname);
                    map.put(TAG_PRICE, price);
                    map.put(TAG_PATH, path);

                    // adding HashList to ArrayList
                    productsList.add(map);
                }
            } else {
                // no products found
                // Launch Add New product Activity
                Intent i = new Intent(getApplicationContext(),
                        NewProductActivity.class);
                // Closing all previous activities
                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(i);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog after getting all products
        pDialog.dismiss();

        runOnUiThread(new Runnable() {
            public void run() {

        adapter=new LazyAdapter(AllProductActivity.this, productsList);
        list.setAdapter(adapter);

            }
        });

    }

}
}

ImageLoader.java

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.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import mygp.gptrade.R;


import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;


public class ImageLoader {

MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new    WeakHashMap<ImageView, String>());
ExecutorService executorService; 

public ImageLoader(Context context){
    fileCache=new FileCache(context);
    executorService=Executors.newFixedThreadPool(5);
}

final int stub_id=R.drawable.ic_launcher;
public void DisplayImage(String url, ImageView imageView)
{
    imageViews.put(imageView, url);
    Bitmap bitmap=memoryCache.get(url);
    if(bitmap!=null)
        imageView.setImageBitmap(bitmap);
    else
    {
        queuePhoto(url, imageView);
        imageView.setImageResource(stub_id);
    }
}

private void queuePhoto(String url, ImageView imageView)
{
    PhotoToLoad p=new PhotoToLoad(url, imageView);
    executorService.submit(new PhotosLoader(p));
}

private Bitmap getBitmap(String url) 
{
    File f=fileCache.getFile(url);

    //from SD cache
    Bitmap b = decodeFile(f);
    if(b!=null)
        return b;

    //from web
    try {
        Bitmap bitmap=null;
        URL imageUrl = new URL(url);
        HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
        conn.setConnectTimeout(30000);
        conn.setReadTimeout(30000);
        conn.setInstanceFollowRedirects(true);
        InputStream is=conn.getInputStream();
        OutputStream os = new FileOutputStream(f);
        Utils.CopyStream(is, os);
        os.close();
        bitmap = decodeFile(f);
        return bitmap;
    } catch (Throwable ex){
       ex.printStackTrace();
       if(ex instanceof OutOfMemoryError)
           memoryCache.clear();
       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=210;
        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*=2;
        }

        //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;
    }
}

class PhotosLoader implements Runnable {
    PhotoToLoad photoToLoad;
    PhotosLoader(PhotoToLoad photoToLoad){
        this.photoToLoad=photoToLoad;
    }

    @Override
    public void run() {
        if(imageViewReused(photoToLoad))
            return;
        Bitmap bmp=getBitmap(photoToLoad.url);
        memoryCache.put(photoToLoad.url, bmp);
        if(imageViewReused(photoToLoad))
            return;
        BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
        Activity a=(Activity)photoToLoad.imageView.getContext();
        a.runOnUiThread(bd);
    }
}

boolean imageViewReused(PhotoToLoad photoToLoad){
    String tag=imageViews.get(photoToLoad.imageView);
    if(tag==null || !tag.equals(photoToLoad.url))
        return true;
    return false;
}

//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
    Bitmap bitmap;
    PhotoToLoad photoToLoad;
    public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
    public void run()
    {
        if(imageViewReused(photoToLoad))
            return;
        if(bitmap!=null)
            photoToLoad.imageView.setImageBitmap(bitmap);
        else
            photoToLoad.imageView.setImageResource(stub_id);
    }
}

public void clearCache() {
    memoryCache.clear();
    fileCache.clear();
}

}

AllProduct.php

<?php

/*
 * Following code will list all the products
 */

// array for JSON response
$response = array();


// include db connect class
require_once 'include/db_connect.php';

// connecting to db
$db = new DB_CONNECT();

// get all products from products table
$result = mysql_query("SELECT *FROM image_detail") or die(mysql_error());

// check for empty result
if (mysql_num_rows($result) > 0) {
// looping through all results
// products node
$response["products"] = array();

while ($row = mysql_fetch_array($result)) {
    // temp user array
    $product = array();
    $product["uid"] = $row["uid"];
    $product["itemname"] = $row["itemname"];
    $product["price"] = $row["price"];
    $product["description"] = $row["description"];






    // push single product into final response array
    array_push($response["products"], $product);
}
// success
$response["success"] = 1;

// echoing JSON response
echo json_encode($response);
} else {
// no products found
$response["success"] = 0;
$response["message"] = "No products found";

// echo no users JSON
echo json_encode($response);
}
?>

日志

05-15 03:44:07.809: D/All Products:(1248): {"success":1,"products":    [{"uid":"1","itemname":"Sdsda","description":"Dsadasdasd","price":"0.00"},{"uid":"2","itemname":"Gagagaga","description":"Gagagaga","price":"0.00"},{"uid":"3","itemname":"Gtr 35","description":"Rm30","price":"0.00"},{"uid":"4","itemname":"Lycan Hypersport","description":"Rm 40","price":"0.00"},{"uid":"5","itemname":"laptop asus","description":"so cheap","price":"20.00"},{"uid":"6","itemname":"xiaomi3","description":"condition 9\/10","price":"50.00"},{"uid":"7","itemname":"acer laptop","description":"freeeeee wajajaja","price":"10.00"},{"uid":"8","itemname":"dell laptop","description":"for sell","price":"60000.00"},{"uid":"9","itemname":"abyss kang","description":"grab it fast","price":"3000000.00"},{"uid":"10","itemname":"botol","description":"cheap je mari la","price":"1.00"},{"uid":"11","itemname":"diao nsksjs","description":"sghsjsjs","price":"444.00"},{"uid":"12","itemname":"cook","description":"cook","price":"20.00"},{"uid":"13","itemname":"cookw","description":"cookw","price":"20.00"},{"uid":"14","itemname":"hahahhaha","description":"hahahhahaa","price":"20.00"},{"uid":"15","itemname":"bola","description":"football yes la","price":"10.00"},{"uid":"16","itemname":"try","description":"try","price":"20.00"},{"uid":"17","itemname":"try2","description":"try2","price":"25.00"},{"uid":"18","itemname":"try3","description":"try3","price":"555.00"},{"uid":"19","itemname":"try4","description":"try4","price":"0.00"},{"uid":"20","itemname":"try5","description":"try5","price":"5.00"},{"uid":"21","itemname":"try6","description":"try6","price":"555.00"},{"uid":"22","itemname":"try7","description":"try7","price":"0.00"},{"uid":"23","itemname":"try8","description":"try8","price":"25.00"},{"uid":"24","itemname":"try9","description":"try9","price":"0.00"},{"uid":"25","itemname":"trt10","description":"trt10","price":"25.00"},{"uid":"26","itemname":"tryee","description":"rrrf","price":"0.00"},{"uid":"27","itemname":"trydd","description":"fff","price":"0.00"},{"uid":"28","itemname":"sr-","description":"dftycfyyhhhy","price":"0.00"},{"uid":"29","itemname":"display flow","description":"display flow","price":"20.00"},{"uid":"30","itemname":"yamcha","description":"yamcha","price":"0.00"},{"uid":"31","itemname":"louis","description":"louis","price":"0.00"}]}
05-15 03:44:07.809: W/System.err(1248): org.json.JSONException: No value for path
05-15 03:44:07.819: W/System.err(1248):     at  org.json.JSONObject.get(JSONObject.java:355)
05-15 03:44:07.819: W/System.err(1248):     at org.json.JSONObject.getString(JSONObject.java:515)
05-15 03:44:07.819: W/System.err(1248):     at  mygp.gptrade.AllProductActivity$LoadAllProducts.doInBackground(AllProductActivity.java:166)
05-15 03:44:07.909: I/Choreographer(1248): Skipped 99 frames!  The application may be doing too much work on its main thread.
05-15 03:44:07.999: I/Choreographer(1248): Skipped 47 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.089: W/System.err(1248):     at mygp.gptrade.AllProductActivity$LoadAllProducts.doInBackground(AllProductActivity.java:1)
05-15 03:44:08.179: I/Choreographer(1248): Skipped 47 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.449: I/Choreographer(1248): Skipped 37 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.529: W/System.err(1248):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
05-15 03:44:08.529: W/System.err(1248):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
05-15 03:44:08.579: I/Choreographer(1248): Skipped 59 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.649: I/Choreographer(1248): Skipped 32 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.729: I/Choreographer(1248): Skipped 30 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.789: I/Choreographer(1248): Skipped 32 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.879: I/Choreographer(1248): Skipped 34 frames!  The application may be doing too much work on its main thread.
05-15 03:44:08.939: I/Choreographer(1248): Skipped 31 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.039: I/Choreographer(1248): Skipped 31 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.299: I/Choreographer(1248): Skipped 44 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.379: W/System.err(1248):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
05-15 03:44:09.379: W/System.err(1248):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
05-15 03:44:09.429: I/Choreographer(1248): Skipped 61 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.499: I/Choreographer(1248): Skipped 42 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.599: I/Choreographer(1248): Skipped 43 frames!  The application may be doing too much work on its main thread.
05-15 03:44:09.859: I/Choreographer(1248): Skipped 38 frames!  The application may be doing too much work on its main thread.
05-15 03:44:10.049: I/Choreographer(1248): Skipped 42 frames!  The application may be doing too much work on its main thread.
05-15 03:44:10.069: W/System.err(1248):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
05-15 03:44:10.069: W/System.err(1248):     at java.lang.Thread.run(Thread.java:841)
05-15 03:44:10.109: I/Choreographer(1248): Skipped 36 frames!  The application may be doing too much work on its main thread.
05-15 03:44:10.319: I/MemoryCache(1248): MemoryCache will use up to 12.0MB
05-15 03:44:10.359: I/Choreographer(1248): Skipped 162 frames!  The application may be doing too much work on its main thread.

Answer 1

添加这个

$product["path"] = $row["path"];

里面

while ($row = mysql_fetch_array($result)) {

希望这能解决您的问题。