我面临一个奇怪的问题。我正在尝试从mysql database中删除所选项目。虽然查询的所有内容都是正确的，但我测试了查询并且它可以正常工作，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, "Items Deleted", Toast.LENGTH_SHORT).show();
adapter.notifyDataSetChanged();
}
});
builder.setNegativeButton(getString(R.string.no), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
builder.create();
builder.show();
}
}
return true;
}
回应：
12-17 05:37:24.043 2099-2099/com.order.app.order E/Names Added:: [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'
添加的名称为：[BLT Sandwich, Club Sandwich]
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文件：
<?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='$trapezi'");
die("Deleted");
?>
仅删除最后一项。有什么想法吗？
答案 0 :(得分：2)
这是因为异步执行。调用deleteDataWebService（）方法只调度DeleteData任务的执行，不立即执行。任务实际上是在一段时间后执行的。
假设在for循环中有两个要删除的项目：
一段时间之后
将值作为参数传递给异步任务而不是通过nameAdapter共享变量传递它将解决问题。此外，不应在任务实例之间共享nameValuePairs。
e.g：
private class DeleteData extends AsyncTask<String, Void, List<CartList>> {
ArrayList<BasicNameValuePair> nameValuePairs;
private void deleteDataInDB(String name){
nameValuePairs.add(new BasicNameValuePair(AppConstant.PRODUCT_NAME_VALUE_PAIR, name));
...
}
...
@Override
protected List<CartList> doInBackground(String... params) {
...
deleteDataInDB(params[1]);
...
}
...
}
private void deleteDataWebService(String name){
DeleteData deleteData = new DeleteData();
deleteData.execute(AppConstant.DELETE_URL, name);
}
答案 1 :(得分：2)
你的问题：
仅删除最后一项。有什么想法吗？
更新查询：
DELETE FROM cart
WHERE product_name='$productName'
AND magazi_id='$magazi'
AND servitoros_id='$servitoros'
AND trapezi='$trapezi'
order by id desc limit 1