多线程Java:在后台用大量行更新JTable
我正在编写一个简单的Java Swing实用程序,它将从MQ JMS服务器读取消息,并在JTable中显示它们
private void getMessages() {
try {
if (null != Queue) {
Queue.close(); //Close previous queue connection if there is one.
}
Queue = new MQQueue(QueueManager, tableQueues.getValueAt(tableQueues.getSelectedRow(), 1).toString(), MQConstants.MQOO_INPUT_SHARED | MQConstants.MQOO_BROWSE | MQConstants.MQOO_OUTPUT, queueManager, null, null);
int count = 0;
modelMessages.setRowCount(0);
MQGetMessageOptions getOptions = new MQGetMessageOptions();
getOptions.options = MQConstants.MQGMO_BROWSE_FIRST;
ArrayList<Object[]> rows = new ArrayList<Object[]>();
while(true) {
if (count > 0) {
getOptions.options = MQConstants.MQGMO_BROWSE_NEXT;
}
MQMessage message = new MQMessage();
try {
Queue.get(message, getOptions);
byte[] b = new byte[message.getMessageLength()];
message.readFully(b);
rows.add(new Object[]{count + 1, new String(b)});
modelMessages.addRow(new Object[]{count + 1, new String(b)});
message.clearMessage();
count++;
}
catch (IOException e) {
break;
}
catch (MQException e) {
if (e.completionCode == 2 && e.reasonCode == MQConstants.MQRC_NO_MSG_AVAILABLE) {
break;
}
}
}
modelMessages.fireTableDataChanged();
} catch (MQException e) {
txtMessage.setText("MQJE001: Completion Code '" + e.completionCode + "', Reason '" + e.reasonCode + "'.");
modelMessages.setRowCount(0);
modelMessages.fireTableDataChanged();
}
}
这对于较小的队列很有效,但对于较大的队列,填充此表需要一段时间,同时Swing应用程序被冻结,因此我正在研究在后台填充JTable的方法,同时不仅要保持应用程序,还要保持JTable本身的可用性和可滚动性
我对穿线不太熟悉,我也尝试过一些方法,比如用SwingUtilities包装一些零件。invokeLater并实现doInBackground(),但似乎没有任何效果。有人能给我指出正确的方向吗
编辑
根据以下回复,以下是解决方案:
public class GetMessagesWorker extends SwingWorker<DefaultTableModel, Object[]> {
//http://stackoverflow.com/questions/22072480/java-updating-jtable-with-lots-of-rows-in-the-background#
private final DefaultTableModel model;
public GetMessagesWorker(DefaultTableModel model){
this.model = model;
}
@Override
protected DefaultTableModel doInBackground() throws Exception {
try {
if (null != Queue) {
Queue.close(); //Close previous queue connection if there is one.
}
Queue = new MQQueue(QueueManager, tableQueues.getValueAt(tableQueues.getSelectedRow(), 1).toString(), MQConstants.MQOO_INPUT_SHARED | MQConstants.MQOO_BROWSE | MQConstants.MQOO_OUTPUT, queueManager, null, null);
int count = 0;
modelMessages.setRowCount(0);
MQGetMessageOptions getOptions = new MQGetMessageOptions();
getOptions.options = MQConstants.MQGMO_BROWSE_FIRST;
while(true) {
if (count > 0) {
getOptions.options = MQConstants.MQGMO_BROWSE_NEXT;
}
MQMessage message = new MQMessage();
try {
Queue.get(message, getOptions);
byte[] b = new byte[message.getMessageLength()];
message.readFully(b);
Object[] row = {count + 1, new String(b)};
publish(row);
message.clearMessage();
count++;
if (isCancelled()) {
modelMessages.setRowCount(0);
count = 0;
message.clearMessage();
return model;
}
}
catch (IOException e) {
break;
}
catch (MQException e) {
if (e.completionCode == 2 && e.reasonCode == MQConstants.MQRC_NO_MSG_AVAILABLE) {
break;
}
}
}
//modelMessages.fireTableDataChanged();
} catch (MQException e) {
txtMessage.setText("MQJE001: Completion Code '" + e.completionCode + "', Reason '" + e.reasonCode + "'.");
modelMessages.setRowCount(0);
modelMessages.fireTableDataChanged();
}
return model;
}
@Override
protected void process(List<Object[]> chunks){
for(Object[] row : chunks){
model.addRow(row);
}
}
}
下面是听众:
tableQueues = new JTable(modelQueues);
tableQueues.getSelectionModel().addListSelectionListener(new ListSelectionListener() {
public void valueChanged(ListSelectionEvent e) {
if (!e.getValueIsAdjusting()) {
txtMessage.setText("");
if (tableQueues.getSelectedRow() > -1) {
gmw.cancel(false);
gmw = new GetMessagesWorker(modelMessages);
gmw.execute();
}
}
}
});
# 1 楼答案
这是由于Swing架构。您必须明白,执行侦听器的同一个线程负责更多的事情(例如,刷新UI)
在你的情况下,我会使用
SwingWorker
。这是一种特定于Swing的后台线程,具有特殊功能,可以在UI执行其长期任务时安全地向其发送更新。你可以在后台完成你的长任务,并调用publish()
获取它检索到的每个相关结果。每次调用publish()
时,都会调用process()
方法(向引擎盖下的主线程发送更新),您可以在那里更新表模型在这里你可以找到更多关于
SwingWorker
的信息:http://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html