如何停止从网络服务器接收数据?
How to stop receiving data from a web server?
我有一个Activity从网络服务器接收和显示信息并将其保存到数据库中,如果它已经接收过一次信息,它将从数据库中读取。
程序没有问题运行,只是当用户进入activity后仍然收不到服务器的信息,退出activity,在另一个Activity 应用程序崩溃。
这个问题是退出activity,因为留在activity完全加载数据时,我们没有任何问题。从数据库中读取数据时也没有任何问题。
如何在用户退出时停止接收数据activity或者通过其他方式解决这个问题。
这是我的 activity 代码:
public class ShowProduct extends AppCompatActivity {
private RequestQueue mQueue;
private String id;
private Products products;
private DatabaseHelper databaseHelper;
private ProgressBar progressBar;
private Typeface IranSans,IranSansBold;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_show_product);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
databaseHelper = new DatabaseHelper(this);
products = new Products();
progressBar = (ProgressBar)findViewById(R.id.progressBar);
IranSans = Typeface.createFromAsset(getAssets(),"fonts/IRANSansWeb.ttf");
IranSansBold = Typeface.createFromAsset(getAssets(),"fonts/IRANSansWeb_Bold.ttf");
Bundle extras = getIntent().getExtras();
id= extras.getString("id");
try {
if (databaseHelper.dbContentChecker(id)) {
if (connectionCheck() == false){
Intent intent = new Intent(this, NoInternetConnection.class);
startActivity(intent);
}
String url = "https://website.com/webserver/?id=" + id;
mQueue = Volley.newRequestQueue(this);
jsonParse(url);
} else {
products = databaseHelper.getOneProduct(id);
showFromDB(products);
}
}catch (Exception ex){
}
//footer set
Footer footer = new Footer();
footer.footerSet(ShowProduct.this, this);
}
private void showFromDB(Products products) {
TextView tx = (TextView)findViewById(R.id.title);
tx.setTypeface(IranSansBold);
tx.setText(products.getName());
ImageView im = (ImageView)findViewById(R.id.image);
Glide.with(ShowProduct.this)
.asBitmap()
.load(products.getImage())
.into(im);
TextView tc = (TextView)findViewById(R.id.content);
tc.setTypeface(IranSans);
tc.setText(Html.fromHtml(products.getContent()));
progressBar.setVisibility(View.GONE);
}
private void jsonParse(String url) {
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("send");
JSONObject send = jsonArray.getJSONObject(0);
String title = send.getString("title");
String image = send.getString("image");
String content = send.getString("content");
TextView tx = (TextView)findViewById(R.id.title);
tx.setTypeface(IranSansBold);
tx.setText(title);
ImageView im = (ImageView)findViewById(R.id.image);
Glide.with(ShowProduct.this)
.asBitmap()
.load(image)
.into(im);
TextView tc = (TextView)findViewById(R.id.content);
tc.setTypeface(IranSans);
tc.setText(Html.fromHtml(content));
//Save in Database
try {
products.setProductId(id);
products.setName(title);
products.setImage(image);
products.setContent(content);
databaseHelper.editProduct(products);
}catch (Exception ex){
Toast.makeText(ShowProduct.this, "Error DB", Toast.LENGTH_SHORT).show();
}
progressBar.setVisibility(View.GONE);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
mQueue.add(request);
//Toast.makeText(getApplicationContext(), ""+Temp , Toast.LENGTH_SHORT).show();
}
public boolean connectionCheck() {
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
if(connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
//we are connected to a network
return true;
}
else
return false;
}
}
首先你应该考虑你的架构。在 Activity 中处理获取数据不是一个好习惯。看看 MVVM 或 MVP,并尝试将您的数据获取逻辑放在另一层。
对于您的具体问题,您应该尝试在 Activity 的 onStop() 方法中取消请求,参见:
我有一个Activity从网络服务器接收和显示信息并将其保存到数据库中,如果它已经接收过一次信息,它将从数据库中读取。
程序没有问题运行,只是当用户进入activity后仍然收不到服务器的信息,退出activity,在另一个Activity 应用程序崩溃。
这个问题是退出activity,因为留在activity完全加载数据时,我们没有任何问题。从数据库中读取数据时也没有任何问题。
如何在用户退出时停止接收数据activity或者通过其他方式解决这个问题。
这是我的 activity 代码:
public class ShowProduct extends AppCompatActivity {
private RequestQueue mQueue;
private String id;
private Products products;
private DatabaseHelper databaseHelper;
private ProgressBar progressBar;
private Typeface IranSans,IranSansBold;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_show_product);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
overridePendingTransition(R.anim.fade_in, R.anim.fade_out);
databaseHelper = new DatabaseHelper(this);
products = new Products();
progressBar = (ProgressBar)findViewById(R.id.progressBar);
IranSans = Typeface.createFromAsset(getAssets(),"fonts/IRANSansWeb.ttf");
IranSansBold = Typeface.createFromAsset(getAssets(),"fonts/IRANSansWeb_Bold.ttf");
Bundle extras = getIntent().getExtras();
id= extras.getString("id");
try {
if (databaseHelper.dbContentChecker(id)) {
if (connectionCheck() == false){
Intent intent = new Intent(this, NoInternetConnection.class);
startActivity(intent);
}
String url = "https://website.com/webserver/?id=" + id;
mQueue = Volley.newRequestQueue(this);
jsonParse(url);
} else {
products = databaseHelper.getOneProduct(id);
showFromDB(products);
}
}catch (Exception ex){
}
//footer set
Footer footer = new Footer();
footer.footerSet(ShowProduct.this, this);
}
private void showFromDB(Products products) {
TextView tx = (TextView)findViewById(R.id.title);
tx.setTypeface(IranSansBold);
tx.setText(products.getName());
ImageView im = (ImageView)findViewById(R.id.image);
Glide.with(ShowProduct.this)
.asBitmap()
.load(products.getImage())
.into(im);
TextView tc = (TextView)findViewById(R.id.content);
tc.setTypeface(IranSans);
tc.setText(Html.fromHtml(products.getContent()));
progressBar.setVisibility(View.GONE);
}
private void jsonParse(String url) {
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("send");
JSONObject send = jsonArray.getJSONObject(0);
String title = send.getString("title");
String image = send.getString("image");
String content = send.getString("content");
TextView tx = (TextView)findViewById(R.id.title);
tx.setTypeface(IranSansBold);
tx.setText(title);
ImageView im = (ImageView)findViewById(R.id.image);
Glide.with(ShowProduct.this)
.asBitmap()
.load(image)
.into(im);
TextView tc = (TextView)findViewById(R.id.content);
tc.setTypeface(IranSans);
tc.setText(Html.fromHtml(content));
//Save in Database
try {
products.setProductId(id);
products.setName(title);
products.setImage(image);
products.setContent(content);
databaseHelper.editProduct(products);
}catch (Exception ex){
Toast.makeText(ShowProduct.this, "Error DB", Toast.LENGTH_SHORT).show();
}
progressBar.setVisibility(View.GONE);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
mQueue.add(request);
//Toast.makeText(getApplicationContext(), ""+Temp , Toast.LENGTH_SHORT).show();
}
public boolean connectionCheck() {
ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
if(connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState() == NetworkInfo.State.CONNECTED ||
connectivityManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState() == NetworkInfo.State.CONNECTED) {
//we are connected to a network
return true;
}
else
return false;
}
}
首先你应该考虑你的架构。在 Activity 中处理获取数据不是一个好习惯。看看 MVVM 或 MVP,并尝试将您的数据获取逻辑放在另一层。
对于您的具体问题,您应该尝试在 Activity 的 onStop() 方法中取消请求,参见: