java - 如何对 Android 中的所有 Activity 使用单一方法？

Question

我正在使用websocket client我的应用程序。在主 Activity 中，我连接到 websocket 客户端并像抽象方法一样执行所有 onMessage、onOpen 操作。我还有两个 Activity ，称为“登录”和“注册” Activity 。我将登录 Activity 中的用户详细信息发送到服务器以进行验证。从服务器我正在 onMessage 抽象方法中的 MainActivity 中接收消息。我需要在登录 Activity 中使用该消息。请解释一下我该如何实现这一目标？如果我在这里重复我的问题，请原谅我并引导我找到正确的答案。

这是我的主要 Activity :

package org.asperohgedgetws.a7.hgadgetws;

import android.app.Activity;
import android.app.Fragment;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.TextView;
import org.java_websocket.client.WebSocketClient;
import org.java_websocket.handshake.ServerHandshake;
import java.net.URI;
import java.net.URISyntaxException;

import android.widget.Button;
import android.widget.Toast;
import android.content.Intent;


public class MainActivity extends Activity implements View.OnClickListener {
Button bLogout;
public static TextView tvReceived;
UserLocalStore userLocalStore;
public static WebSocketClient mWebSocketClient;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    bLogout = (Button) findViewById(R.id.bLogout);
    bLogout.setOnClickListener(this);
    userLocalStore = new UserLocalStore(this);
    tvReceived = (TextView) findViewById(R.id.tvRecieved);

    connectWebSocket();
}
@Override
protected void onStart() {
    super.onStart();
    if (authenticate()){
        displayUserDetails();
    } else{
        Toast.makeText(getApplicationContext(), "Not Registered User :(", Toast.LENGTH_SHORT).show();
        startActivity(new Intent(MainActivity.this,Login.class));
    }
}

private boolean authenticate(){
    return userLocalStore.getUserLoggedIn();
}

private void displayUserDetails(){
    User user = userLocalStore.getLoggedInUser();
}

@Override
public void onClick(View v) {
    switch(v.getId()){
        case R.id.bLogout:
            startActivity(new Intent(this,Login.class));
            userLocalStore.clearUserData();
            userLocalStore.setUserLoggedIn(false);
            Toast.makeText(getApplicationContext(), "Logout :)", Toast.LENGTH_SHORT).show();

            break;

    }
}

public void connectWebSocket() {
    URI uri;
    try {
        uri = new URI("ws://xxx.xxx.xxx:xxxx");
    } catch (URISyntaxException e) {
        e.printStackTrace();
        return;
    }

    mWebSocketClient = new WebSocketClient(uri) {
        @Override
        public void onOpen(ServerHandshake serverHandshake) {
            Log.i("Websocket", "Opened");
            //mWebSocketClient.send("Hello from " + Build.MANUFACTURER + " " + Build.MODEL);
            //mWebSocketClient.send("{\"1512BD002\":\"SO@0\":\"2\"}");
        }

        @Override
        public void onMessage(String s) {
            //final String message = s;
             final String WSmessage = s;
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(), WSmessage, Toast.LENGTH_SHORT).show();
                    tvReceived.setText(WSmessage);
                    Log.i("Websocket_Message", WSmessage);
                    //TextView textView = (TextView)findViewById(R.id.messages);
                    //textView.setText(textView.getText() + "\n" + message);
                }
            });
        }

        @Override
        public void onClose(int i, String s, boolean b) {
            Log.i("Websocket", "Closed " + s);
        }

        @Override
        public void onError(Exception e) {
            Log.i("Websocket", "Error " + e.getMessage());
        }
    };
    mWebSocketClient.connect();
}

public void sendMessage(View view) {
 //   EditText editText = (EditText)findViewById(R.id.message);
   // mWebSocketClient.send(editText.getText().toString());
    //editText.setText("");
}
}

和登录 Activity 包 org.asperohgedgetws.a7.hgadgetws;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.gson.Gson;
import android.app.ProgressDialog;
import java.util.LinkedHashMap;
import java.util.Map;

public class Login extends AppCompatActivity implements View.OnClickListener {

Button bLogin;
EditText etUsername, etPassword;
TextView tvRegisterLink;
UserLocalStore userLocalStore;

/**
 * ATTENTION: This was auto-generated to implement the App Indexing API.
 * See https://g.co/AppIndexing/AndroidStudio for more information.
 */


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    etUsername = (EditText) findViewById(R.id.etUsername);
    etPassword = (EditText) findViewById(R.id.etPassword);
    tvRegisterLink = (TextView) findViewById(R.id.tvRegisterLink);
    bLogin = (Button) findViewById(R.id.bLogin);
    bLogin.setOnClickListener(this);
    userLocalStore = new UserLocalStore(this);
    tvRegisterLink.setOnClickListener(this);
    // ATTENTION: This was auto-generated to implement the App Indexing API.
    // See https://g.co/AppIndexing/AndroidStudio for more information.
}

@Override
public void onBackPressed() {
    new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Exit")
            .setMessage("Are you sure?")
            .setPositiveButton("yes", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    Intent intent = new Intent(Intent.ACTION_MAIN);
                    intent.addCategory(Intent.CATEGORY_HOME);
                    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                    startActivity(intent);
                    finish();
                }
            }).setNegativeButton("no", null).show();
}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.bLogin:
if ((Login.this.etUsername.getText().toString().trim().length() > 0) && (Login.this.etPassword.getText().toString().trim().length() > 0)) {
                String username = etUsername.getText().toString();
                String password = etPassword.getText().toString();
                User user = new User(username, password);
                userLocalStore.storeUserData(user);

                Map obj = new LinkedHashMap();
                obj.put("id", user.username);
                obj.put("password", user.password);
                obj.put("type", "signin");
                obj.put("user.", "normal");

                Gson gson = new Gson();
                String json = gson.toJson(obj);
                System.out.println(json);
                Log.i("Ordered Json", json);
                ProgressDialog pd = new ProgressDialog(Login.this);
                pd.setMessage("loading");
                pd.show();
                MainActivity.mWebSocketClient.send(json);
//Here I want to use received Message from Server to Authenticate User.
                return;
            }
            Log.i("Login ERROR", "Username OR Password Missing");
            new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Error")
                    .setMessage("Email ID or Password Missing")
                    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) { }
                    }).show();

            break;
        case R.id.tvRegisterLink:
            Toast.makeText(getApplicationContext(), "Register :)", Toast.LENGTH_SHORT).show();
            startActivity(new Intent(this, Register.class));
            break;
    }

}

编辑:

大家好，我刚刚浏览了 Android 服务、单例和 Android 广播接收器示例。我只是想，如果我使用 Android 服务进行网络连接(Websocket)管理、数据传输和接收并使用 Android 广播来通知特定 Activity 有新的传入消息会怎样？

Answer 1

我认为使用 Activity 来处理服务器通信是错误的方法。虽然 LoginActivity 可见，但 MainActivity 位于后台，系统可能随时终止它，导致套接字连接消失。

这似乎是应该使用服务完成的任务的完美案例。实现所需的逻辑，例如设置套接字以及在服务中发送和接收消息，并将其绑定(bind)到 Activity 中的“onCreate”方法中。一旦服务绑定(bind)，您就可以询问服务用户是否已登录或请求登录用户。因为服务随后会接收消息，所以您需要一种方法来向 Activity 报告。这可以通过广播或观察者来实现。对于后一种情况，您可能需要为观察者和服务创建 AIDL 接口(interface)，这实际上并不难。

如果您不在应用程序中使用不同的进程，您也可以简单地创建一个单例而不是服务，并在不同的 Activity 中使用它。如果需要，您还可以稍后将单例放入服务中。

至于例子，除了 default Service documentation 我想不出任何例子。