jButton1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("點(diǎn)擊登錄");
            }
        });

jButton2.addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
                System.out.println("鼠標(biāo)點(diǎn)擊");
            }

            @Override
            public void mousePressed(MouseEvent e) {
                System.out.println("鼠標(biāo)按下，但沒(méi)有松開(kāi)");
            }

            @Override
            public void mouseReleased(MouseEvent e) {
                System.out.println("鼠標(biāo)松開(kāi)");
            }

            @Override
            public void mouseEntered(MouseEvent e) {
                System.out.println("鼠標(biāo)懸停");
            }

            @Override
            public void mouseExited(MouseEvent e) {
                System.out.println("鼠標(biāo)移走");
            }
        });

jTextField.addKeyListener(new KeyListener() {
            @Override
            public void keyTyped(KeyEvent e) {
//                System.out.println("鍵盤(pán)輸入完成");
            }

            @Override
            public void keyPressed(KeyEvent e) {
//                System.out.println("鍵盤(pán)按下");
            }

            @Override
            public void keyReleased(KeyEvent e) {
//                "釋放鍵盤(pán)"
                System.out.println(jTextField.getText());
            }
        });

this.addWindowListener(new WindowAdapter() {//窗口適配器WindowAdapter，也可使用new WindowListener()
            @Override
            public void windowClosing(WindowEvent e) {
                int res = JOptionPane.showConfirmDialog(null,"確定退出聊天室？","操作提示",JOptionPane.OK_CANCEL_OPTION);//彈出一個(gè)對(duì)話框
                if (res == 0){//確認(rèn)退出
                    dispose()；
                }
            }
        });

JOptionPane.showMessageDialog(null, "發(fā)送內(nèi)容不能為空");

JOptionPane.showConfirmDialog(null,"確定退出聊天室？","操作提示",JOptionPane.OK_CANCEL_OPTION);