java - 如何在切换Fragment时停止AsyncTask？

Question

我正在使用底部导航栏，切换 fragment 时异步任务不起作用，需要等待8到10分钟才能从异步任务获取响应。由于Asynctask问题，所有页面都没有数据可显示。请帮我解决这个问题。谢谢 fragment 切换代码:

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected( MenuItem item) {
        Fragment fragment=null;
        switch (item.getItemId()) {
            case R.id.navigation_home:
                fragment = new HomeFragment();
                break;
            case R.id.navigation_market:
                fragment=new MarketFragment();
                break;
            case R.id.navigation_agent:
                fragment=new AgentFragment();
                break;
            case R.id.navigation_finance:
                fragment=new FinanceFragment();
                break;
           /* case R.id.navigation_more:
                MoreFragment moreFragment=new MoreFragment();
                moreFragment.show(getSupportFragmentManager(),moreFragment.getTag());*/
        }
        closeContextMenu();
        return loadFragment(fragment);
    }
};
private boolean loadFragment(Fragment fragment) {
    if (fragment != null) {
        getSupportFragmentManager()
                .beginTransaction()
                .replace(R.id.fragment_container, fragment)
                .commit();
        return true;
    }
    return false;
}```

异步任务代码:我已经在所有 fragment 中实现了这样的 asynctask。

        JSONObject jsonObject, jsonObject2;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            SignupActivity.this.layoutProgress.setVisibility(View.VISIBLE);
        }
        @Override
        protected String doInBackground(Void... voids) {
            HashMap<String, String> map = new HashMap<>();
            map.put("countrycode",code);
            map.put("phonenumber",phone);
            map.put("emailid",email);
            map.put("agentname",fullname);
            map.put("username",username);
            map.put("password",lpassword);
            map.put("confirmpassword",conlpassword);
            map.put("transactionpassword",spassword);
            map.put("transactionconfirmpassword",conspassword);
            return new HttpHandler().sendPostRequest(Config.url + "JoinNowRegister",map);
        }
        @Override
        protected void onPostExecute(String response) {
            super.onPostExecute(response);
            Toast.makeText(getApplicationContext(), "test", Toast.LENGTH_LONG).show();
            try {
                jsonObject = new JSONObject(response);
                if(jsonObject.getString("statuscode").equals("1")){
                    message = jsonObject.getString("status");
                    jsonObject2 = jsonObject.getJSONObject("data");
                    id = jsonObject2.getString("agentid");
                    int code=Integer.parseInt(jsonObject2.getString("countrycode"));
                    String phonenumber= jsonObject2.getString("phone");
                    storeCode(code);
                    storePhone(phonenumber);
                    Intent intent;
                    intent = new Intent(SignupActivity.this, OtpActivity.class);
                    Bundle bundle = new Bundle();
                    bundle.putString("agentid",id);
                    intent.putExtras(bundle);
                    startActivity ( intent );
                    finish();
                }
                else{
                    msg=jsonObject.getString("data");
                    Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            } catch (NullPointerException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }
            SignupActivity.this.layoutProgress.setVisibility(View.GONE);
        }
    }   

Answer 1

在您的 fragment 中使用它，它将停止 AsyncTask...

@Override
protected void onDestroy() {
    super.onDestroy();
    // cancel running task(s) to avoid memory leaks
    if (runningTask != null) runningTask.cancel(true);
}