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调用我的显示消息来更新列表视图。

我收到错误消息“只有创建视图层次结构的原始线程才能接触其视图。”

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列表视图。

这是我的主要活动。

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。在后台线程中移动更新 ui 的代码。您正在后台线程上刷新列表视图。

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

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

以上应该是线程外的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();
    }
}
}
}
}