android - 如何在 Android 中管理 Activity 的 onPause、onResume 自定义适配器

Question

我有一个适配器，用于在 ListView 中显示消息，在聊天应用程序中查看类似的消息。创建 Activity 后，我能够完美地显示内容，但是当我返回并再次创建 Activity 时，适配器无法正常工作。

调试时发现如下:

• 函数 receives() 在收到消息时调用并更新注册，正如我上面提到的，显示是没有问题的创建 Activity 后 ListView 中的数据，但一旦我返回并重新启动我无法显示收到的消息的 Activity 。

关于自定义适配器的 onResume() onPause 或 onStart() 方法是否缺少某些内容，例如再次注册或取消自定义适配器？感谢您的帮助。

以下是我的 Activity 类的代码，它使用自定义适配器来显示已发送和已接收的消息:

public class hotListener extends ListActivity {


    private XMPPConnection connection;
    private IBinder binder;
    private Handler mHandler = new Handler();
    private ArrayList<String> messages = new ArrayList<String>();
    ArrayList<ChatMessage> messagex= new ArrayList<ChatMessage>();;
    ChattingAdapter adaptex;

    Intent mIntent ;
    private ListView listview;
    EditText sender_message ;
    String msg;


    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.listener);
        //messagex.add(new ChatMessage("Hello", false));
        adaptex  = new ChattingAdapter(getApplicationContext(),messagex);
        setListAdapter(adaptex);

        Button send_button = (Button) findViewById(R.id.chat_send_message);
        sender_message = (EditText) findViewById(R.id.chat_input);
        send_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                msg = sender_message.getText().toString();
                sender_message.setText("");
                if(!(msg.length()==0)){
                    messagex.add(new ChatMessage(msg, true));
                    //addNewMessage(new ChatMessage(msg, true));
                    adaptex.notifyDataSetChanged();
                    getListView().setSelection(messagex.size()-1);
                }

            }
        });
        if(!isMyServiceRunning()){
            System.out.println("seems like service not running");
            startService(new Intent(this,xService.class));
            System.out.print(" now started ");
        }       
    }

    @Override
    protected void onStart(){
        super.onStart();
        Boolean kuch = bindService(new Intent(this,xService.class), mConnection,Context.BIND_AUTO_CREATE);
        //System.out.println(kuch);
        System.out.println("bind done");        
    }

    private void receives(XMPPConnection connection2) {
            //ChatManager chatmanager = connection.getChatManager();
            connection2.getChatManager().addChatListener(new ChatManagerListener() {

                @Override
                public void chatCreated(Chat arg0, boolean arg1) {
                    arg0.addMessageListener(new MessageListener() {

                        @Override
                        public void processMessage(Chat chat, Message message) {

                            final String from = message.getFrom();
                            final String body = message.getBody();
                            mHandler.post(new Runnable() {
                                ChatMessage kudi = new ChatMessage(body, false);

                                @Override
                                public void run() {

                                    messagex.add(kudi);
                                    adaptex.notifyDataSetChanged();
                                    getListView().setSelection(messagex.size()-1);
                                    Toast.makeText(hotListener.this,body,Toast.LENGTH_SHORT).show();                                }
                            });
                        }
                    });
                }
            });
    }

    private boolean isMyServiceRunning() {
        ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        for(RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)){
            if(xService.class.getName().equals(service.service.getClassName())){
                return true;
            }
        }
        //System.out.print("false");
        return false;
    }

    @Override
      protected void onResume() {
        bindService(new Intent(this, xService.class), mConnection, Context.BIND_AUTO_CREATE);
        super.onResume();
      }
     @Override
      protected void onPause() {
        unbindService(mConnection);
        super.onPause();
      }

     private ServiceConnection mConnection = new ServiceConnection() {

            @Override
            public void onServiceDisconnected(ComponentName name) {
                connection = null;
                service = null;
            }

            @Override
            public void onServiceConnected(ComponentName name, IBinder binder) {
                //System.out.println("binding in hot listener");
                service = ((xService.MyBinder)binder).getService();
                connection = service.getConnection();
                receives(connection);
                Log.wtf("Service","connected");
            }
        };

        void addNewMessage(ChatMessage m)
        {
            System.out.println("1");
            messagex.add(m);
            System.out.println("2");
            adaptex.notifyDataSetChanged();
            System.out.println("3");
            getListView().setSelection(messagex.size()-1);
        }
}

这是我的自定义适配器(自定义适配器没有问题，但添加以明确说明):

public class ChattingAdapter extends BaseAdapter{
    private Context mContext;
    private ArrayList<ChatMessage> mMessages;


    public ChattingAdapter(Context context, ArrayList<ChatMessage> messages) {
        super();
        this.mContext = context;
        this.mMessages = messages;
    }
    @Override
    public int getCount() {
        return mMessages.size();
    }
    @Override
    public Object getItem(int position) {       
        return mMessages.get(position);
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ChatMessage message = (ChatMessage) this.getItem(position);

        ViewHolder holder; 
        if(convertView == null)
        {
            holder = new ViewHolder();
            convertView = LayoutInflater.from(mContext).inflate(R.layout.listitem, parent, false);
            holder.message = (TextView) convertView.findViewById(R.id.text1);
            convertView.setTag(holder);
        }
        else
            holder = (ViewHolder) convertView.getTag();

        holder.message.setText(message.getMessage());
        LayoutParams lp = (LayoutParams) holder.message.getLayoutParams();      

        //Check whether message is mine to show green background and align to right

        if(message.isMine())

        {           holder.message.setBackgroundResource(R.drawable.msgbox_new_selected_go_up);         

                lp.gravity = Gravity.RIGHT;     
        }
        //If not mine then it is from sender to show orange background and align to left

        else        
        {
            holder.message.setBackgroundResource(R.drawable.msgbox_other_go_up);

            lp.gravity = Gravity.LEFT;

        }
            holder.message.setLayoutParams(lp);
            //holder.message.setTextColor(R.color.textColor);   

        return convertView;
    }
    private static class ViewHolder
    {
        TextView message;
    }

    @Override
    public long getItemId(int position) {
        //Unimplemented, because we aren't using Sqlite.
        return position;
    }

}

p.s:我没有在 sqlite 中存储任何消息，因为我现在不想恢复消息，但我希望至少在 Activity 恢复时显示新消息。我可以在按下发送按钮后显示已发送的消息，但没有收到消息，这在第一次创建 Activity 时工作正常。

编辑:我做了更多的调试，结果发现问题不在恢复 Activity 中，如果我第一次不使用 receives() 函数，并且在返回后恢复 Activity ，那么 receives() 将起作用，这意味着，函数在 receives() 内部:getListView().setSelection(messagex.size()-1); 只工作一次。要么是第一次收到消息，要么是下一次，当且仅当它不是第一次在 Activity 中被调用。

Answer 1

我认为问题在于当您尝试恢复 Activity 时，您仍在运行之前的 mHandler 运行，因此您的消息实例没有被破坏，当您恢复 Activity 时它会产生问题。确保您的 mhandler 在调用 unstop 时销毁​​所有对象实例。