我们如何处理ConnectException？

Question

我已经搜索了很多,但我找不到它的正确答案.我使用try_catch块进行此异常(如果抛出此异常,将向用户显示一个帧,我将告诉他/她一条消息)但是它仍然在控制台中显示异常.请帮助我.谢谢.

submit()方法将抛出此异常:

  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,这是一个登录按钮的动作:

 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);
    }
}

堆栈跟踪:

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

您在上一个问题中发布了代码:登录按钮在Java应用程序中没有可见效果

根据该runAClient方法判断,您正在记录异常并将其吃掉(不要再抛弃它).

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);
    }
}

第二个catch(IOException)不应该记录并且应该抛出异常.实际上,您可能希望将该catch捕获到您将抛出的ConnectException catch以及可以单独处理的IOException catch.

编辑:我会稍微扩展一下.ConnectException扩展RemoteException,然后扩展IOException,您正在捕获并记录您的runAClient方法.你可以做两件事:

• IOException完全删除,并在上层捕获它(我认为这是一个非常难看的解决方案)

要么

• 将IOException块拆分为两个catch块,一个用于ConnectException您刚刚抛出的块,另一个用于其余的IOExceptions,您可以记录(或以不同的方式处理) - 只需确保ConnectException块在IOException块之前写入