我們如何處理ConnectException？

Question

我已經搜索了很多，但找不到合適的答案。我為此異常使用try_catch塊（如果拋出此異常，則會向用戶顯示一幀，我會告訴他/她一個消息），但是它仍然在控制台中顯示異常。請幫助我。謝謝。

Submit（）方法將拋出此異常：

  private void submit() throws ConnectException {

    String id = idField.getText();
    char[] pass1 = passField.getPassword();
    String pass = new String(pass1);
    if (id.equals("") || pass.equals("")) {
        JOptionPane.showMessageDialog(this, "You should enter an ID and password", "Sign_In Problem", JOptionPane.OK_OPTION);
        return;
    } else {
        boolean b = Manager.Test(id, pass);
        if (b == true) {
            this.setVisible(false);

            Main.runAClient();

            ListFrame frame = new ListFrame(client);
            frame.setVisible(true);





        } else {

            JOptionPane.showMessageDialog(this, "You have entered wrong datas,try it again", "Sign_In Problem", JOptionPane.OK_OPTION);
            return;
        }
    }
}

我使用netbeans，這是登錄按鈕的操作：

 private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    try {
        submit();
    } catch (ConnectException ex) {
        JOptionPane.showMessageDialog(this, "You coudn't connect to the server successfully,try it again", "Sign_In Problem", JOptionPane.OK_OPTION);

    }}

我的runAClient方法：

 public static void runAClient()throws ConnectException{
    try {
        c = new Socket("localhost", 5000);
    } catch (ConnectException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    }
}

堆棧跟蹤：

init:
deps-jar:
compile-single:
run-single:
Jan 11, 2010 5:20:35 PM ClientNetWork.Main runAClient
SEVERE: null
java.net.ConnectException: Connection refused: connect
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
        at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
        at java.net.Socket.connect(Socket.java:518)
        at java.net.Socket.connect(Socket.java:468)
        at java.net.Socket.<init>(Socket.java:365)
        at java.net.Socket.<init>(Socket.java:179)
        at ClientNetWork.Main.runAClient(Main.java:29)
        at ClientGUI.MainFrame.submit(MainFrame.java:335)
        at ClientGUI.MainFrame.jButton1ActionPerformed(MainFrame.java:233)
        at ClientGUI.MainFrame.access$400(MainFrame.java:34)
        at ClientGUI.MainFrame$5.actionPerformed(MainFrame.java:122)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.AbstractButton.doClick(AbstractButton.java:357)
        at javax.swing.plaf.basic.BasicRootPaneUI$Actions.actionPerformed(BasicRootPaneUI.java:191)
        at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1636)
        at javax.swing.JComponent.processKeyBinding(JComponent.java:2849)
        at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:267)
        at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:216)
        at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2926)
        at javax.swing.JComponent.processKeyBindings(JComponent.java:2918)
        at javax.swing.JComponent.processKeyEvent(JComponent.java:2812)
        at java.awt.Component.processEvent(Component.java:5815)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
        at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:697)
        at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:962)
        at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:834)
        at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:661)
        at java.awt.Component.dispatchEventImpl(Component.java:4282)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

Answer 1

您在上一個問題中張貼了代碼：“ 登錄”按鈕在Java應用程序中沒有可見的作用

通過runAClient方法判斷，您正在記錄異常並吞噬異常（不會進一步拋出異常）。

public static void runAClient() {
    try {
        c = new Socket("localhost", 5000);
    } catch (UnknownHostException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    } catch (IOException ex) {
        Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
    }
}

第二個catch（ IOException ）不應該記錄並且應該引發異常。 實際上，您可能希望將該捕獲分為要拋出的ConnectException捕獲和可以單獨處理的IOException捕獲。

編輯：我將對此進行擴展。 ConnectException擴展了RemoteException ，后者又擴展了IOException ，您正在捕獲並登錄runAClient方法。 您可以做兩件事：

• 完全刪除IOException ，並在更高級別捕獲它（我認為這是非常丑陋的解決方案）

要么

• 將IOException塊分成兩個catch塊，一個用於您剛剛拋出的ConnectException ，另一個用於其余IOException ，您可以記錄（或以其他方式處理）-只需確保在ConnectException塊寫入之前IOException塊

Answer 2

你有代碼嗎

  Main.runAClient();

也許有人正在捕獲該異常並將其記錄下來，然后重新拋出？