我有一个应用程序从网站接收json数据，然后解析它以编程方式显示在我的应用程序上。我现在面临的问题是，如果我关闭应用程序并重新启动它，相同的数据会重复，我不想要。所以请有人帮我解决这个问题。以下是将数据映射到我的应用程序的类的代码。
public class FirstScreen extends Activity {
// int numberquantity;
JSONParse Jp=new JSONParse();
// URL to get JSON Array
private static String url = "http://10.0.2.2/SUPERSHOP/supershop_api.php";
private static final String TAG_USER = "record";
private static final String TAG_NAME = "Name";
private static final String TAG_PRICE = "Price";
private static final String TAG_IMAGE_PATH="http://10.0.2.2/bootstrap-dist/images/";
private static final String TAG_DESCRIPTION = "Description";
JSONArray user = null;
// private ProgressDialog pDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Controller aController = (Controller) getApplicationContext();
aController.getCart().clearCart();
Jp.execute();
}
Bitmap drawable_from_url(String url) throws java.net.MalformedURLException, java.io.IOException {
Bitmap x;
HttpURLConnection connection = (HttpURLConnection)new URL(url) .openConnection();
connection.setRequestProperty("User-agent","Mozilla/4.0");
connection.connect();
InputStream input = connection.getInputStream();
x = BitmapFactory.decodeStream(input);
return x;
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(FirstScreen.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
@Override
protected JSONObject doInBackground(String... args) {
JSONParser jParser = new JSONParser();
// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl(url);
return json;
}
@Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
Controller aController = (Controller) getApplicationContext();
ModelProducts productObject = null;
JSONObject c=null;
try {
// Getting JSON Array
user = json.getJSONArray(TAG_USER);
for(int i=0;i<user.length();i++){
c = user.getJSONObject(i);
// Storing JSON item in a Variable
String name = c.getString(TAG_NAME);
String prices= c.getString(TAG_PRICE);
int price=Integer.parseInt(prices);
String description = c.getString(TAG_DESCRIPTION);
String imagePath=c.getString("Picture");
String Url=imagePath;
// Create product model class object
productObject = new ModelProducts(name,description,Url, price, 0, 0);
// store product object to arraylist in controller
aController.setProducts(productObject);
onResume();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
/******************end of parser****************************/
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
Bitmap bitmap;
// ImageLoader class instance
ImageLoader imgLoader = new ImageLoader(getApplicationContext());
setContentView(R.layout.firstscreen);
final LinearLayout lm = (LinearLayout) findViewById(R.id.linearMain);
final Button secondBtn = (Button) findViewById(R.id.second);
ModelProducts productObject = null;
// Get Global Controller Class object (see application tag in
// AndroidManifest.xml)
final Controller aController = (Controller) getApplicationContext();
/****************** Products Data Creation Begins ***********/
/******* Create view elements dynamically and show on activity ******/
// Product arraylist size
int ProductsSize = aController.getProductsArraylistSize();
// create the layout params that will be used to define how your
// button will be displayed
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
/******** Dynamically create view elements - Start **********/
for (int j = 0; j < ProductsSize; j++) {
// Get probuct data from product data arraylist
String pName = aController.getProducts(j).getProductName();
final String pDsc = aController.getProducts(j).getProductDesc();
String pUrl=aController.getProducts(j).getImageUrl();
final int pPrice = aController.getProducts(j).getProductPrice();
// int pQuantity = aController.getProducts(j).getProductQuantity();
//Toast.makeText(FirstScreen.this,pUrl, Toast.LENGTH_SHORT).show();
// Create LinearLayout to view elemnts
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.HORIZONTAL);
// settingup images to show in cataglog
ImageView image = new ImageView(this);
imgLoader.DisplayImage("http://10.0.2.2/bootstrap-dist/"+pUrl, image);
//ll.addView(image);
ll.addView(image);
TextView product = new TextView(this);
product.setText(" " + pName + " ");
// Add textView to LinearLayout
ll.addView(product);
TextView price = new TextView(this);
price.setText(pPrice +": Tk"+ " ");
// Add textView to LinearLayout
ll.addView(price);
TextView quantity = new TextView(this);
quantity.setText(" " + "Quantity:" + " ");
// Add textView to LinearLayout
ll.addView(quantity);
final EditText inpquantity = new EditText(this);
inpquantity.setText("1");
ll.addView(inpquantity);
final Button btn = new Button(this);
btn.setId(j + 1);
ModelProducts tempProductObject = aController.getProducts(j);
if (!aController.getCart().checkProductInCart(tempProductObject)) {
btn.setText("Add To Cart");
}else{
btn.setText("Added");
}
//btn.setText("Add To Cart");
// set the layoutParams on the button
btn.setLayoutParams(params);
final int index = j;
//to stop the keypad from popping up
this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
// Created click listener for dynamically created button
btn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
int numberquantity = Integer.parseInt(inpquantity.getText()
.toString());
int trackID = 0;
// ModelProducts productobj=new ModelProducts(pName, pDsc,
// pPrice,numberquantity);
aController.updateProduct(index).setProductQuantity(
numberquantity);
// Clicked button index
Log.i("TAG", "index :" + index);
// Get product instance for index
ModelProducts tempProductObject = aController
.getProducts(index);
// Check Product already exist in Cart or Not
if (!aController.getCart().checkProductInCart(
tempProductObject)) {
btn.setText("Added");
// saving data of button id of items added to cart to a
// shared preference.
trackID = btn.getId();
// Product not Exist in cart so add product to
// Cart product arraylist
aController.getCart().setProducts(tempProductObject);
Toast.makeText(
getApplicationContext(),
"Now Cart size: "
+ aController.getCart().getCartSize(),
Toast.LENGTH_LONG).show();
}
}
});
// Add button to LinearLayout
ll.addView(btn);
// Add LinearLayout to XML layout
lm.addView(ll);
}
// aController.getProductsArraylist().clear();
/******** Dynamically create view elements - End **********/
secondBtn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Intent i = new Intent(getBaseContext(), Secondscreen.class);
startActivity(i);
}
});
}
}
答案 0 :(得分：0)
我不确定你重复自己的意思。你是说你得到两次json数据还是意味着它再次下载json数据？
无论如何，只要你在onCreate上执行json Parse，每次你关闭并再次打开Activity时都会下载json数据。
也不要将onResume用作功能。看起来每次重新输入活动时JSON Parser以及Android LifeCycle都会打开onResume。这意味着，你在onResume中设置TextViews代码会被执行两次，因为JSON Parser和普通onResume Call将被执行两次。尝试将onResume中的代码移动到其他位置，然后在onPostExecute中调用此方法。
答案 1 :(得分：0)
每次调用
时都必须清除ModelProducts.class