如何将AsyncTask中的字符串从服务器获取到MainActivity

Question

我想显示从服务器获得的字符串，该服务器位于MainActivitytextView上的AsyncTask(或我称之为MessageSender类)中。我知道我需要使用setText()方法。我正在从服务器获取字符串，它显示在控制台中。

这是我的MessageSender类：

public class MessageSender  extends AsyncTask<String, Object, String>  {
Socket socket;
ObjectInputStream ois;
ObjectOutputStream oos;
BufferedInputStream bis;
Object player;
String userName;
String level;
String input = null;
@Override
protected String doInBackground(String... strings) {
userName = strings [0];
level = strings [1];
player =  userName +"n" + level ;
try {
socket= new Socket("192.168.1.179", 8884);
System.out.println("********************");
System.out.println("Connected to server");
System.out.println("********************");
oos = new ObjectOutputStream(socket.getOutputStream());
oos.writeObject(player);
oos.flush();
ois = new ObjectInputStream(socket.getInputStream());
input = ois.readUTF();
System.out.println(input);
} catch (IOException e) {
e.printStackTrace();
//  socket.close();
}
return input;
}
}

这是我的MainActivity类：

package com.example.whack_a_mole;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import com.google.android.material.button.MaterialButton;
public class MainActivity4 extends AppCompatActivity {
private TextView textView;
private MaterialButton newGameBtn;
MessageSender ms=new MessageSender();

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main4);
textView=findViewById(R.id.first_place);
textView.setText(ms.input);
newGameBtn= findViewById(R.id.newGameBtn);
newGameBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent= new Intent(MainActivity4.this, MainActivity.class);
startActivity(intent);
//uppdatera listan
}
});
}
}

Answer 1

AsyncTask已被弃用，请考虑使用其他内容。

---

您可以创建一个接口，例如用一个方法onInputReceived:调用它MessageInputListener

public interface MessageInputListener {
public void onInputReceived(String input);
}

通过MainActivity4实现该接口，将MessageInputListener作为参数添加到MessageSender构造函数中，在创建MessageSender的实例时在MainActivity4中传递this，并在MessageSender:中实现onPostExecute方法

public class MainActivity4 extends AppCompatActivity implements MessageInputListener {
// ...

MessageSender ms = new MessageSender(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// ...

ms.execute(...);
}
@Override
public void onInputReceived(String input) {
textView.setText(input);
}
}
public class MessageSender  extends AsyncTask<String, Object, String>  {
//...
private MessageInputListener mListener;
public MessageSender(MessageInputListener listener) {
mListener = listener;
}
@Override
protected void onPostExecute(String message) {
if (mListener != null) {
mListener.onInputReceived(message)
}
}
}