java - Android 问题基于套接字动态更新 ListView

Question

我有一个 android 应用程序，它是一个简单聊天服务器的客户端。我能够连接到服务器和我的 ObjectStreams。问题是当我收到一条消息时，处理我的服务器连接的线程会根据我更新 ListView 的显示消息调用。

我收到错误“只有创建 View 层次结构的原始线程才能触及它的 View 。”

我很确定这是因为我正在从我的连接线程调用我的 displayMessage() 方法，但我不确定如何组织我的线程以连接到服务器并动态更新我的 ListView 。

这是我的主要 Activity 。

public class MainActivity extends Activity {

private Connection serverConnection;
private ArrayList<String> listItems = new ArrayList<String>();
private ArrayAdapter<String> adapter;
/**
 * Sets the ArrayAdaptor, and starts the connectThread. 
 */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    runOnUiThread(new Runnable() {
        public void run() {
            ListView listview = (ListView) findViewById(R.id.list);
            adapter = new ArrayAdapter<String>(MainActivity.this,
                    android.R.layout.simple_list_item_1, 
                            listItems);
            listview.setAdapter(adapter);
        }
    }); 
    /**
     * Starts a new connection Thread
     */
    Thread connectThread = new Thread(new Runnable(){
        public void run(){
            serverConnection = new Connection(MainActivity.this);
            serverConnection.run();
        }
    });
    connectThread.start();
}
/**
 * Adds a message to the list view. 
 * @param string - message to be added. 
 */
public void displayMessage(String string) {
    listItems.add(string);
    adapter.notifyDataSetChanged();
}
}

这是我的连接线程类。

public class Connection extends Thread {

private Socket client;
private ObjectOutputStream output;
private ObjectInputStream input;
private MainActivity mainActivity;
private String message;
/**
 * Constructor starts the socket and ObjectStreams
 * 
 * @param mainActivity - reference to the MainActivity
 */
public Connection(MainActivity mainActivity) {
    this.mainActivity = mainActivity;
    try {
        client = new Socket("192.168.1.105", 50499);
        mainActivity.displayMessage("Connected to: "
                + client.getInetAddress().getHostName());
        output = new ObjectOutputStream(client.getOutputStream());
        output.flush();
        input = new ObjectInputStream(client.getInputStream());
    } catch (IOException e) {
        e.printStackTrace();
    }

}
/**
 * Run method for the Thread. 
 */
public void run() {
    for (;;) {
        try {
            message = (String) input.readObject();
            mainActivity.displayMessage(message);
        } catch (OptionalDataException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
}

Answer 1

您正在后台线程上更新 Ui。您应该在 ui 线程上更新 ui。移动在后台线程中更新 ui 的代码。您正在后台线程上刷新 ListView 。

 mainActivity.displayMessage("Connected to: "
            + client.getInetAddress().getHostName()); 
 mainActivity.displayMessage(message);

 public void displayMessage(String string) {
   listItems.add(string);
   adapter.notifyDataSetChanged(); 
   }

上面应该在线程外或者你可以在线程内使用runonuithread来更新ui。

      runOnUiThread(new Runnable() {
            @Override
            public void run() {
               // update ui 
            }
        });

另一种方法是使用异步任务。在 doInbackground() 中执行所有与网络相关的操作，并在 onPostExecute() 中更新 ui。

Async Task

编辑:不确定您要做什么。

 public class MainActivity extends Activity {

 private Connection serverConnection;
 private ArrayList<String> listItems = new ArrayList<String>();
 private ArrayAdapter<String> adapter;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
        ListView listview = (ListView) findViewById(R.id.lv);
        adapter = new ArrayAdapter<String>(MainActivity.this,
                android.R.layout.simple_list_item_1, 
                        listItems);
        listview.setAdapter(adapter);
     // use a button and on button click start the thread.

Thread connectThread = new Thread(new Runnable(){
    public void run(){
        serverConnection = new Connection(MainActivity.this);
        serverConnection.run();
    }
});
connectThread.start();
}

public void displayMessage(String string) {
listItems.add(string);
adapter.notifyDataSetChanged();
}
class Connection extends Thread {

private Socket client;
private ObjectOutputStream output;
private ObjectInputStream input;
private MainActivity mainActivity;
private String message;

public Connection(MainActivity mainActivity) {
this.mainActivity = mainActivity;
try {
    client = new Socket("192.168.1.105", 50499);
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            displayMessage("Connected to: "
                   );
        }
    });

    output = new ObjectOutputStream(client.getOutputStream());
    output.flush();
    input = new ObjectInputStream(client.getInputStream());
} catch (IOException e) {
    e.printStackTrace();
}
}

 public void run() {
 for (;;) {
    try {
          message = (String) input.readObject();
          runOnUiThread(new Runnable() {
              @Override
              public void run() {
                displayMessage(message);
              }
          });



    } catch (OptionalDataException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
}
}
}