【发布时间】：2014-11-04 12:48:05
【问题描述】：
我在这里看到并阅读了很多帖子，但我仍然无法将这些图像从 mysql 获取到我的应用程序。我还使用了一个邮政编码，并尝试为我的应用采用，但应用仍然崩溃。 我用过这个帖子How to JSON parse images from mysql and populate listview
private ListView listView;
private StockAdaptor stockAdaptor;
String jsonResult = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.restaurants); //Just a listView, shown below
listView = (ListView) findViewById(R.id.restaurants);
new JsonReadTask().execute("http://link"); //YOUR URL JSON SERVER, IF IT IS DIFFERENT FROM THAT SUPPLIED ABOVE
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
return true; //No options
}
public void onStart() {
super.onStart();
stockAdaptor = new StockAdaptor(this); //Create a new StockAdaptor
}
public static String strFromStream(InputStream in) throws IOException { //Simple function, getting a String from an InputStream
StringBuilder out = new StringBuilder();
BufferedReader breader = new BufferedReader(new InputStreamReader(in));
String cline;
String newLine = System.getProperty("line.separator");
while ((cline = breader.readLine()) != null) {
out.append(cline);
out.append(newLine);
}
return out.toString();
}
private class StockAdaptor extends BaseAdapter { //The stocks list adaptor
class ViewHolder {
TextView name;
TextView menu;
ImageView image;
}
private LayoutInflater layoutInflater;
private RestaurantInformation[] stocks = null; //Array of stocks
public StockAdaptor(Context context) {
super();
layoutInflater = LayoutInflater.from(context);
}
public void setStockList(RestaurantInformation[] stocksinfo) {
this.stocks = stocksinfo;// //////////////LITERALLY THIS
}
@Override
public int getCount() {
return stocks.length;
}
@Override
public Object getItem(int position) {
return stocks[position];
}
@Override
public long getItemId(int position) {
return 0;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder; //New holder
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.restaurant_information, null);
holder = new ViewHolder();
// Creates the new viewholder define above, storing references to the children
holder.name = (TextView) convertView.findViewById(R.id.name);
holder.menu = (TextView) convertView.findViewById(R.id.menu);
holder.image = (ImageView) convertView.findViewById(R.id.image);
if (holder.image != null) {
if (holder.image.getDrawable() == null) {
new ImageDownloaderTask(holder.image, null)
.execute(stocks[position].image); //Download the image using the image
}
}
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.name.setText(stocks[position].name);
holder.menu.setText(stocks[position].menu);
return convertView;
}
}
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
if (URLUtil.isValidUrl(params[0])) {
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(params[0]);
try {
HttpResponse response = client.execute(getRequest);
final HttpEntity httpentity = response.getEntity();
if (httpentity != null){
InputStream inputStream = null;
try {
inputStream = httpentity.getContent();
jsonResult = strFromStream(inputStream);
Log.i("", jsonResult);
return jsonResult;
} catch (IllegalArgumentException e) {
//
} finally {
httpentity.consumeContent();
}
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
client.close();
}
}
return null;
}
@Override
protected void onPostExecute(String result) {
ListDrwaer();
}
}// end async task
// build hash set for list view
public void ListDrwaer() {
try {
if (jsonResult!=null) {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("metoxes");
Vector<RestaurantInformation> restaurants = new Vector<RestaurantInformation>();
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
RestaurantInformation stock = new RestaurantInformation();
stock.name = jsonChildNode.optString("name");
stock.menu = jsonChildNode.optString("menu");
stock.image = jsonChildNode.getString("image");
Log.i("StockLog", stock.name + stock.menu + stock.image);
restaurants.add(stock);
}
RestaurantInformation[] stocks = new RestaurantInformation[jsonMainNode.length()];
int stockscount = jsonMainNode.length();
for (int n = 0; n < stockscount; n++)
{
stocks[n] = restaurants.get(n);
}
stockAdaptor.setStockList(stocks);
listView.setAdapter(stockAdaptor);
} else {
Toast.makeText(getApplicationContext(), "Error; jsonResult null",
Toast.LENGTH_SHORT).show();
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
}
private class ImageDownloaderTask extends AsyncTask<String, Void, Bitmap> {
private final WeakReference<ImageView> imageViewReference;
public ImageDownloaderTask(ImageView imageView, View view) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
// Actual download method, run in the task thread
protected Bitmap doInBackground(String... params) {
// params comes from the execute() call: params[0] is the url.
return downloadBitmap(params[0]);
}
@Override
// Once the image is downloaded, associates it to the imageView
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
if (imageView != null) {
if (bitmap != null) {
imageView.setImageBitmap(bitmap);
} else {
//
}
}
}
}
Bitmap downloadBitmap(String url) {
if(URLUtil.isValidUrl(url)){
final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
final HttpGet getRequest = new HttpGet(url);
try {
HttpResponse response = client.execute(getRequest);
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
Log.w("ImageDownloader", "Error " + statusCode
+ " while retrieving bitmap from " + url);
return null;
}
final HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream inputStream = null;
try {
inputStream = entity.getContent();
try {
byte[] buffer = new byte[8192];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
while ((bytesRead = inputStream.read(buffer)) != -1) {
output.write(buffer, 0, bytesRead);
}
return BitmapFactory.decodeByteArray(output.toByteArray(), 0, output.toByteArray().length);
} catch (IllegalArgumentException e) {
e.printStackTrace();
Log.i("IAE", "in stocks");
return null;
}
} finally {
if (inputStream != null) {
inputStream.close();
}
entity.consumeContent();
}
}
} catch (Exception e) {
getRequest.abort();
Log.w("ImageDownloader", "Error while retrieving bitmap from " + url);
} finally {
if (client != null) {
client.close();
}
}
return null;
}
return null;
}
}
还有XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:minHeight="50dp"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<ImageView
android:id="@+id/image"
android:layout_width="70dp"
android:layout_height="70dp" />
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:lineSpacingExtra="3dp"
android:paddingLeft="5dp"
android:paddingTop="5dp"
android:text="" />
<TextView
android:id="@+id/menu"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="5dp"
android:paddingTop="5dp"
android:text="" />
</LinearLayout>
</LinearLayout>
我在LogCat 中的错误是这样的。
11-04 07:39:13.880: E/AndroidRuntime(831): FATAL EXCEPTION: main
11-04 07:39:13.880: E/AndroidRuntime(831): Process: com.reserveme, PID: 831
11-04 07:39:13.880: E/AndroidRuntime(831): java.lang.NullPointerException
11-04 07:39:13.880: E/AndroidRuntime(831): at com.reserveme.Restaurants.ListDrwaer(Restaurants.java:198)
11-04 07:39:13.880: E/AndroidRuntime(831): at com.reserveme.Restaurants$JsonReadTask.onPostExecute(Restaurants.java:184)
11-04 07:39:13.880: E/AndroidRuntime(831): at com.reserveme.Restaurants$JsonReadTask.onPostExecute(Restaurants.java:1)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.os.AsyncTask.finish(AsyncTask.java:632)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.os.AsyncTask.access$600(AsyncTask.java:177)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.os.Handler.dispatchMessage(Handler.java:102)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.os.Looper.loop(Looper.java:136)
11-04 07:39:13.880: E/AndroidRuntime(831): at android.app.ActivityThread.main(ActivityThread.java:5017)
11-04 07:39:13.880: E/AndroidRuntime(831): at java.lang.reflect.Method.invokeNative(Native Method)
11-04 07:39:13.880: E/AndroidRuntime(831): at java.lang.reflect.Method.invoke(Method.java:515)
11-04 07:39:13.880: E/AndroidRuntime(831): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
11-04 07:39:13.880: E/AndroidRuntime(831): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
11-04 07:39:13.880: E/AndroidRuntime(831): at dalvik.system.NativeStart.main(Native Method)
更新：
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
RestaurantInformation stock = new RestaurantInformation(); <--- THIS LINE
stock.name = jsonChildNode.optString("name");
stock.menu = jsonChildNode.optString("menu");
stock.image = jsonChildNode.getString("image");
Log.i("StockLog", stock.name + stock.menu + stock.image);
restaurants.add(stock);
}
更新
这是服务器端.php 文件
<?php
$host="localhost"; //replace with database hostname
$username="user"; //replace with database username
$password="pass"; //replace with database password
$db_name="dbname"; //replace with database name
$con=mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");
$sql = "select * from Restaurants";
$result = mysql_query($sql);
$json = array();
if(mysql_num_rows($result)){
while($row=mysql_fetch_assoc($result)){
$json['Restaurants'][]=$row;
}
}
mysql_close($con);
echo json_encode($json);
?>
【问题讨论】：
-
你能指出第 198 行吗？
-
@Rohit5k2，当然，我已经更新了我的问题。
RestaurantInformation stock = new RestaurantInformation(); -
请看我的回答