我面临着一个奇怪的问题.我试图从
mysql数据库中删除所选项目.虽然查询的一切都是正确的,我测试了查询,它的工作,但它不会从数据库中删除项目.
代码：
private class DeleteData extends AsyncTask<String,Void,List<CartList>> {
@Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog = new ProgressDialog(CartActivity.this);
progressDialog.setMessage(getString(R.string.get_stocks));
progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
progressDialog.setIndeterminate(true);
progressDialog.setCancelable(false);
progressDialog.show();
}
@Override
protected List<CartList> doInBackground(String... params) {
nameValuePairs = new ArrayList<>();
cartItems = new ArrayList<>();
try {
url = new URL(params[0]);
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setReadTimeout(10000);
httpURLConnection.setConnectTimeout(15000);
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoInput(true);
httpURLConnection.setDoOutput(true);
deleteDataInDB();
outputStream = httpURLConnection.getOutputStream();
bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream));
bufferedWriter.write(StringGenerator.queryResults(nameValuePairs));
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
httpURLConnection.connect();
inputStream = new BufferedInputStream(httpURLConnection.getInputStream());
jsonResult = StringGenerator.inputStreamToString(inputStream,CartActivity.this);
Log.e("Response: ",jsonResult.toString());
} catch (IOException e) {
e.printStackTrace();
}
return cartItems;
}
@Override
protected void onPostExecute(List<CartList> cartLists) {
super.onPostExecute(cartLists);
progressDialog.dismiss();
}
}
设置方法：
private void deleteDataInDB(){
nameValuePairs.add(new BasicNameValuePair(AppConstant.PRODUCT_NAME_VALUE_PAIR,nameAdapter));
Log.e("Name Adapter Value: ",nameAdapter);
nameValuePairs.add(new BasicNameValuePair(AppConstant.COMPANY_INTENT_ID,magazi_id));
Log.e("Magazi id: ",magazi_id);
nameValuePairs.add(new BasicNameValuePair(AppConstant.PRODUCT_WAITER_ID_VALUE_PAIR,servitoros_id));
Log.e("Servitoros id: ",servitoros_id);
nameValuePairs.add(new BasicNameValuePair(AppConstant.PRODUCT_TABLE_ID_VALUE_PAIR,table));
Log.e("Table: ",table);
}
我执行任务的地方：
@Override
public boolean onActionItemClicked(ActionMode mode,MenuItem item) {
switch (item.getItemId()){
case R.id.deleteCartItemModification:{
for (int position = 0; position<names.size(); position++){
nameAdapter = names.get(position);
deleteDataWebService();
adapter.notifyItemRemoved(position);
}
setupTotalValue();
Toast.makeText(CartActivity.this,"Items Deleted",Toast.LENGTH_SHORT).show();
adapter.notifyDataSetChanged();
AlertDialog.Builder builder = new AlertDialog.Builder(CartActivity.this);
builder.setTitle(getString(R.string.delete));
builder.setMessage(getString(R.string.delete_msg));
builder.setPositiveButton(getString(R.string.yes),new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,int which) {
deleteDataWebService();
Toast.makeText(CartActivity.this,Toast.LENGTH_SHORT).show();
adapter.notifyDataSetChanged();
}
});
builder.setNegativeButton(getString(R.string.no),int which) {
dialog.cancel();
}
});
builder.create();
builder.show();
}
}
return true;
}
响应：
12-17 05:37:24.043 2099-2099/com.order.app.order E/NamesAdded:: [BLT Sandwich,Club Sandwich] 12-17 05:37:24.045 2099-2099/com.order.app.order I/AppCompatDelegate: The Activity's LayoutInflater already has a Factory installed so we can not install AppCompat's 12-17 05:37:24.086 2099-2118/com.order.app.order W/EGL_emulation: eglSurfaceAttrib not implemented 12-17 05:37:24.086 2099-2118/com.order.app.order W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xa0883cc0,error=EGL_SUCCESS 12-17 05:37:26.390 2099-2118/com.order.app.order D/OpenGLRenderer: endAllStagingAnimators on 0xa1ce1b00 (RippleDrawable) with handle 0xa18d8700 12-17 05:37:26.417 2099-2123/com.order.app.order E/Response:: DELETE FROM cart WHERE product_name='Club Sandwich' AND magazi_id='53' AND servitoros_id='724' AND trapezi='3' 12-17 05:37:26.430 2099-2118/com.order.app.order W/EGL_emulation: eglSurfaceAttrib not implemented 12-17 05:37:26.430 2099-2118/com.order.app.order W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xa0883cc0,error=EGL_SUCCESS 12-17 05:37:26.445 2099-2123/com.order.app.order E/Response:: DELETE FROM cart WHERE product_name='Club Sandwich' AND magazi_id='53' AND servitoros_id='724' AND trapezi='3'
响应是最后一个对象的两倍：
E/Response:: DELETE FROM cart WHERE product_name='Club Sandwich' AND magazi_id='53' AND servitoros_id='724' AND trapezi='3' E/Response:: DELETE FROM cart WHERE product_name='Club Sandwich' AND magazi_id='53' AND servitoros_id='724' AND trapezi='3'
deleteDataWebService：
private void deleteDataWebService(){
DeleteData deleteData = new DeleteData();
deleteData.execute(AppConstant.DELETE_URL);
}
<?PHP ini_set("default_charset","UTF-8"); header('Content-type: text/html; charset=UTF-8'); try { $handler = new PDO('MysqL:host=my_server;dbname=database','username','password'); $handler->setAttribute(PDO::MysqL_ATTR_INIT_COMMAND,"SET NAMES utf8 "); $handler->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION); $handler->exec("SET CHARACTER SET 'utf8'"); } catch (Exception $e) { echo $e->getMessage(); die(); } $productName = $_POST['productName']; $magazi = $_POST['magazi_id']; $servitoros = $_POST['servitoros_id']; $trapezi = $_POST['trapezi']; $handler->query("DELETE FROM cart WHERE product_name='$productName' AND magazi_id='$magazi' AND servitoros_id='$servitoros' AND trapezi='$trapezi'"); die("Deleted"); ?>
只有最后一个项目被删除.有任何想法吗？
这是因为异步执行.调用deleteDataWebService()方法仅调度执行DeleteData任务,不会立即执行.任务实际上是在一段时间后进行的.
假设你有两个要删除的项目,在for循环中：
> nameAdapter为item1设置,
>任务计划执行,
> nameAdapter为item2设置,
一段时间之后
> task2使用nameAdapter执行任务,
> task2使用nameAdapter执行任务,
将值作为参数传递给异步任务,而不是通过nameAdapter共享变量传递它将解决问题.也可以在任务实例之间共享nameValuePairs.
例如：
private class DeleteData extends AsyncTask<String,List<CartList>> {
ArrayList<BasicNameValuePair> nameValuePairs;
private void deleteDataInDB(String name){
nameValuePairs.add(new BasicNameValuePair(AppConstant.PRODUCT_NAME_VALUE_PAIR,name));
...
}
...
@Override
protected List<CartList> doInBackground(String... params) {
...
deleteDataInDB(params[1]);
...
}
...
}
private void deleteDataWebService(String name){
DeleteData deleteData = new DeleteData();
deleteData.execute(AppConstant.DELETE_URL,name);
}
