manager.java

有关j2me的很好的例子可以研究一下

    }

    /**
     * Ask the user for the URL.
     */
    private void getUrl() {
        try {
            if (urlTextBox == null) {
                urlTextBox = new TextBox(Resource.getString(
                                         "Enter a website to Install From:"),
                                         defaultInstallListUrl, 1024,
                                         TextField.ANY);
                urlTextBox.addCommand(backCmd);
                urlTextBox.addCommand(selectSuiteCmd);
                urlTextBox.setCommandListener(this);
            }

            display.setCurrent(urlTextBox);
        } catch (Exception ex) {
            Alert a = new Alert(Resource.getString("Exception"), 
                                ex.toString(), null, AlertType.ERROR);
            a.setTimeout(Alert.FOREVER);
            display.setCurrent(a, mlist);
        }
    }

    /**
     * Ask the user for the settings.
     */
    private void getSettings() {
        if (settingsTextBox == null) {
            settingsTextBox = new TextBox(Resource.getString(
                                 "Set Website URL"), null,
                                 1024, TextField.ANY);
            settingsTextBox.addCommand(backCmd);
            settingsTextBox.addCommand(saveSettingsCmd);
            settingsTextBox.setCommandListener(this);
        }

        settingsTextBox.setString(defaultInstallListUrl);
        display.setCurrent(settingsTextBox);
    }

    /**
     * Save the settings the user entered.
     */
    private void saveSettings() {
        String temp;
        ByteArrayOutputStream bas;
        DataOutputStream dos;
        byte[] data;
        RecordEnumeration records;
        RecordStore settings;
        
        temp = settingsTextBox.getString();
        if (temp == null) {
            display.setCurrent(mlist);
            return;
        }

        try {
            bas = new ByteArrayOutputStream();
            dos = new DataOutputStream(bas);
            dos.writeUTF(temp);
            data = bas.toByteArray();
            settings = RecordStore.openRecordStore(SETTINGS_STORE, true);
            records = settings.enumerateRecords(null, null, false);
            if (records.numRecords() == 0) {
                settings.addRecord(data, 0, data.length);
            } else {
                settings.setRecord(records.nextRecordId(), data, 0,
                                   data.length);
            }

            settings.closeRecordStore();

            defaultInstallListUrl = temp;
            if (urlTextBox != null) {
                urlTextBox.setString(defaultInstallListUrl);
            }

            displaySuccessMessage(Resource.getString("Saved!"));
        } catch (Exception ex) {
            Alert a = new Alert(Resource.getString("Exception"), 
                                ex.toString(), null, AlertType.ERROR);
            a.setTimeout(Alert.FOREVER);
            display.setCurrent(a, mlist);
        }
    }

    /**
     * Get the settings the Manager saved for the user.
     */
    private void restoreSettings() {
        ByteArrayInputStream bas;
        DataInputStream dis;
        byte[] data;
        RecordEnumeration records;
        RecordStore settings = null;
        
        try {
            settings = RecordStore.openRecordStore(SETTINGS_STORE, false);
            records = settings.enumerateRecords(null, null, false);

            if (records.numRecords() == 0) {
                return;
            }

            data = records.nextRecord();
            bas = new ByteArrayInputStream(data);
            dis = new DataInputStream(bas);
            
            defaultInstallListUrl = dis.readUTF();
            return;
        } catch (RecordStoreException e) {
            // ignore
        } catch (IOException e) {
            // ignore
        } finally {
            if (settings != null) {
                try {
                    settings.closeRecordStore();
                } catch (RecordStoreException e) {
                    // ignore
                }
            }
        }
    }

    /**
     * Let the user select a suite to install. The suites that are listed
     * are the links on a web page that end with .jad.
     *
     * @param url where to get the list of suites to install.
     */
    private void selectSuiteToInstall(String url) {
        new Thread(new BackgroundInstallListGetter(this, url)).start();
    }

    /**
     * Install a suite.
     *
     * @param selectedSuite index into the installList
     */
    private void installSuite(int selectedSuite) {
        SuiteDownloadInfo suite;

        suite = (SuiteDownloadInfo)installList.elementAt(selectedSuite);
        cancelledMessage = Resource.getString("Installation cancelled.");
        finishingMessage = Resource.getString("Finishing installation.");
        installSuiteCommon("Installing", suite.label, suite.url,
            suite.label + Resource.getString(" was successfully installed"),
            false);
    }

    /**
     * Install a suite.
     *
     * @param action action to put in the form's title
     * @param name name to in the form's title
     * @param url URL of a JAD
     * @param successMessage message to display to user upon success
     * @param overwriteFlag if true the current suite should be
     *                      overwritten without asking the user.
     */
    private void installSuiteCommon(String action, String name, String url,
            String successMessage, boolean overwriteFlag) {
        Form installForm;

        try {
            installForm = displayConnectingForm(action, name, url);
            installForm.addCommand(stopCmd);
            installForm.setCommandListener(this);
            backgroundInstaller = new BackgroundInstaller(this, url, name,
                                      successMessage, overwriteFlag);
            new Thread(backgroundInstaller).start();
        } catch (Exception ex) {
            StringBuffer sb = new StringBuffer()
                .append(name)
                .append("\n")
                .append(Resource.getString("Error"))
                .append(": ")
                .append(ex.toString());

            Alert a = new Alert(Resource.getString("Cannot access: "), 
                                sb.toString(), null, AlertType.ERROR);
            a.setTimeout(Alert.FOREVER);
            display.setCurrent(a, mlist);
            return;
        }
    }

    /**
     * Ask a username and password.
     */
    private void getUsernameAndPassword() {
        if (passwordForm == null) {
            passwordForm = new Form(null);

            usernameField = new TextField(
                            Resource.getString("Please Enter ID"), null, 40,
                            TextField.ANY);
            passwordForm.append(usernameField);

            passwordField = new TextField(
                            Resource.getString("Password"), null, 40,
                            TextField.PASSWORD);
            passwordForm.append(passwordField);
            passwordForm.addCommand(cancelInstallCmd);
            passwordForm.addCommand(nextCmd);
            passwordForm.setCommandListener(this);
        }

        passwordField.setString("");
        display.setCurrent(passwordForm);
    }

    /**
     * Resume the install of the suite with a password and username.
     */
    private void resumeInstallWithPassword() {
        String username;
        String password;


        username = usernameField.getString();
        password = passwordField.getString();
        if (username == null || username.length() == 0) {
            Alert a = new Alert(Resource.getString("Error"), 
                                Resource.getString(
                                "The ID has not been entered."),
                                null, AlertType.ERROR);
            a.setTimeout(ALERT_TIMEOUT);
            display.setCurrent(a, passwordForm);
            return;
        }

        if (password == null || password.length() == 0) {
            Alert a = new Alert(Resource.getString("Error"), 
                                Resource.getString(
                                "The password has not been entered."),
                                null, AlertType.ERROR);
            a.setTimeout(ALERT_TIMEOUT);
            display.setCurrent(a, passwordForm);
            return;
        }

        // redisplay the progress form
        display.setCurrent(conForm);

        backgroundInstaller.installState.setUsername(username);
        backgroundInstaller.installState.setPassword(password);

        backgroundInstaller.continueInstall = true;
        backgroundInstaller.installState.notify();
    }

    /**
     * Give the user a chance to act on warning during an installation.
     *
     * @param name name of the MIDlet suite to insert into the message
     * @param jadUrl URL of a JAD, can be null
     * @param e last exception from the installer
     */
    private void warnUser(String name, String jadUrl, InvalidJadException e) {
        Form warningForm;
        String extraConfirmMsg;

        warningForm = new Form(null);
        warningForm.setTitle(Resource.getString("Warning"));
        warningForm.append(translateJadException(e, name, jadUrl)); 
        warningForm.addCommand(cancelInstallCmd);
        warningForm.addCommand(okCmd);
        warningForm.setCommandListener(this);
        display.setCurrent(warningForm);
    }

    /**
     * Update the status form.
     *
     * @param status current status of the install.
     */
    private void updateStatus(int status) {
        if (status != Installer.STORING_SUITE) {
            return;
        }

        displaySuccessMessage(finishingMessage);
    }

    /**
     * Resume the install after a the user overrides a warning.
     */
    private void resumeInstallAfterWarning() {
        // redisplay the progress form
        display.setCurrent(conForm);

        backgroundInstaller.continueInstall = true;
        backgroundInstaller.installState.notify();
    }

    /** Cancel an install (if there is one) waiting for user input. */
    private void cancelBackgroundInstall() {
        if (backgroundInstaller != null &&
                backgroundInstaller.installState != null) {
            backgroundInstaller.installState.notify();
        }
    }

    /**
     * Display the connecting form to the user.
     *
     * @param action action to put in the form's title
     * @param name name to in the form's title
     * @param url URL of a JAD
     *
     * @return displayed form
     */
    private Form displayConnectingForm(String action, String name,
                                       String url) {
        Image icon;

        conForm = new Form(null);

        conForm.setTitle(Resource.getString(action) + " " + name);

        icon = getIconFromStorage(
                                  (colorDisplay ? "_dt_8.png" : "_dt_2.png"));
        conForm.append(new ImageItem(null, icon, ImageItem.LAYOUT_CENTER +
                                     ImageItem.LAYOUT_NEWLINE_BEFORE +
                                     ImageItem.LAYOUT_NEWLINE_AFTER, null));

        conForm.append(action);
        conForm.append(Resource.getString(" from"));
        conForm.append(": ");
        conForm.append(url);

        display.setCurrent(conForm);

        return conForm;
    }

    /**
     * Alert the user that an action was successful.
     * @param successMessage message to display to user
     */
    private void displaySuccessMessage(String successMessage) {
        Image icon;
        Alert successAlert;

        icon = getIconFromStorage(
                       (colorDisplay ? "_dukeok8.png" : "_dukeok2.png"));

        successAlert = new Alert(null, successMessage, icon, null);

        successAlert.setTimeout(ALERT_TIMEOUT);

        // We need to prevent "flashing" on fast development platforms.
        while (System.currentTimeMillis() - lastDisplayChange < ALERT_TIMEOUT);

        lastDisplayChange = System.currentTimeMillis();

        display.setCurrent(successAlert, mlist);
    }

    /**
     * Alert the user that an action was canceled. The backgroundInstaller
     * will hide the message.
     * @param message message to display to user
     */
    private void displayCancelledMessage(String message) {
        Form form;
        Image icon;

        form = new Form(null);

        icon = getIconFromStorage(
                       (colorDisplay ? "_ack_8.png" : "_ack_2.png"));
        form.append(new ImageItem(null, icon, ImageItem.LAYOUT_CENTER +
                                     ImageItem.LAYOUT_NEWLINE_BEFORE +
                                     ImageItem.LAYOUT_NEWLINE_AFTER, null));

        form.append(message);

        display.setCurrent(form);
    }

    /**