Java 在oncreateview中使用异步任务
有没有办法在Java 在oncreateview中使用异步任务,java,android,httpurlconnection,oncreate,fragment-oncreateview,Java,Android,Httpurlconnection,Oncreate,Fragment Oncreateview,有没有办法在oncreateview方法中用异步任务覆盖“week_kg”变量? 异步任务覆盖变量,但视图已创建,且不包含新值 这是一个与Node.js服务器和Mysql数据库的Rest通信 public class Feedback extends Fragment { private RecyclerView mRecylcerView; private RecyclerView.Adapter mAdapter; private RecyclerView.Layou
oncreateview
方法中用异步任务覆盖“week_kg”变量?
异步任务覆盖变量,但视图已创建,且不包含新值
这是一个与Node.js服务器和Mysql数据库的Rest通信
public class Feedback extends Fragment {
private RecyclerView mRecylcerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
public String username = "ilovenature";
public double week_kg;
String resturl = "http://192.168.178.199:3000/"; //ip
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_feedback, container, false);
new HttpGet().execute(resturl + "user/" + username);
ArrayList < Feedback_inhalt > feedback_inhalt = new ArrayList<>();
feedback_inhalt.add(new Feedback_inhalt(R.mipmap.ic_plastic_color, "Verwertungskosten", "kg eingespart", week_kg));
mRecylcerView = view.findViewById(R.id.feedback_view);
mRecylcerView.setHasFixedSize(true);
mLayoutManager = new LinearLayoutManager(this.getActivity());
mAdapter = new FeedbackAdapter(feedback_inhalt);
mRecylcerView.setLayoutManager(mLayoutManager);
mRecylcerView.setAdapter(mAdapter);
return view;
}
public class HttpGet extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String...strURLs) {
URL url;
String output;
HttpURLConnection conn;
try {
url = new URL(strURLs[0]);
conn = (HttpURLConnection) url.openConnection();
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuilder sb = new StringBuilder();
while ((output = br.readLine()) != null) {
sb.append(output);
}
return sb.toString();
} catch (IOException e) {
return "Unable to retrieve web page. URL may be invalid.";
}
}
@Override
protected void onPostExecute(String result) {
try {
JSONArray jsonArray = new JSONArray(result);
JSONObject jsonObject = jsonArray.getJSONObject(0);
week_kg = jsonObject.getDouble("wochenkilogramm");
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
公共类反馈扩展片段{
私人回收视图mRecylcerView;
专用回收器查看适配器mAdapter;
private RecyclerView.LayoutManager MLLayoutManager;
公共字符串username=“iloventure”;
公众双周(公斤);;
字符串resturl=”http://192.168.178.199:3000/“;//ip
@凌驾
CreateView上的公共视图(布局、充气机、视图组容器、捆绑包保存状态){
视图=充气机。充气(R.layout.fragment\u反馈,容器,错误);
新建HttpGet().execute(resturl+“user/”+用户名);
ArrayListFeedback\u inhalt=new ArrayList();
添加新的反馈(R.mipmap.ic塑料颜色,“Verwertungskosten”,“kg eingespart”,week\u kg));
mRecylcerView=view.findviewbyd(R.id.feedback\u视图);
mRecylcerView.setHasFixedSize(true);
mLayoutManager=newlinearlayoutmanager(this.getActivity());
mAdapter=新反馈适配器(反馈接口);
mRecylcerView.setLayoutManager(mLayoutManager);
mRecylcerView.setAdapter(mAdapter);
返回视图;
}
公共类HttpGet扩展异步任务{
@凌驾
受保护的字符串背景(字符串…字符串){
网址;
字符串输出;
httpurl连接连接;
试一试{
url=新url(strURLs[0]);
conn=(HttpURLConnection)url.openConnection();
BufferedReader br=新的BufferedReader(新的InputStreamReader(conn.getInputStream());
StringBuilder sb=新的StringBuilder();
而((output=br.readLine())!=null){
附加(输出);
}
使某人返回字符串();
}捕获(IOE异常){
return“无法检索网页。URL可能无效。”;
}
}
@凌驾
受保护的void onPostExecute(字符串结果){
试一试{
JSONArray JSONArray=新JSONArray(结果);
JSONObject JSONObject=jsonArray.getJSONObject(0);
周_kg=jsonObject.getDouble(“沃肯千克”);
}捕获(JSONException e){
e、 printStackTrace();
}
}
}
}
创建视图时只调用一次onCreateView()
方法
但是,一旦AsyncTask
完成执行,就可以刷新RecyclerView
。为此,请将新获取的数据添加到ArrayList反馈中,然后在适配器上调用notifyDataSetChanged()
调用notifyDataSetChanged()
时,视图将基于ArrayList中的数据进行刷新
因此,在设置了week\u kg
的值之后,在onPostExecute()内:
feedback_inhalt.add(new Feedback_inhalt(R.mipmap.ic_plastic_color, "Verwertungskosten", "kg eingespart", week_kg));
mAdapter.notifyDatSetChanged()
最后,只能从UI线程调用notifyDataSetChanged()
方法,但onPostExecute()
方法是通过设计在UI线程上运行的,因此您可以选择:-)