Vaadin登录页面问题

时间：2014-09-12 13:11:47

标签： vaadin vaadin7

我是Vaadin UI开发的新手，请原谅我有任何愚蠢的错误。有人可以帮忙吗？

我正在尝试使用Vaadin网站中提到的链接https://vaadin.com/wiki/-/wiki/Main/Creating+a+simple+login+view来构建登录页面。但是我收到错误 - com.vaadin.server.ServiceException：java.lang.RuntimeException：java.lang.InstantiationException

有3个班级

1）登录视图 2）主视图 3）在2个视图之间导航的主类

1）登录视图如下：

public abstract class SimpleLoginView extends CustomComponent implements View, Button.ClickListener { 

private static final long serialVersionUID = 1L;

public static final String NAME = "login";

private final TextField user;

private final PasswordField password;

private final Button loginButton;

public SimpleLoginView() {
    setSizeFull();

    // Create the user input field
    user = new TextField("User:");
    user.setWidth("300px");
    user.setRequired(true);
    user.setInputPrompt("Your username (eg. joe@email.com)");
    user.addValidator(new EmailValidator(
            "Username must be an email address"));
    user.setInvalidAllowed(false);

    // Create the password input field
    password = new PasswordField("Password:");
    password.setWidth("300px");
    password.addValidator(new PasswordValidator());
    password.setRequired(true);
    password.setValue("");
    password.setNullRepresentation("");

    // Create login button
    loginButton = new Button("Login", this);

    // Add both to a panel
    VerticalLayout fields = new VerticalLayout(user, password, loginButton);
    fields.setCaption("Please login to access the application. (test@test.com/passw0rd)");
    fields.setSpacing(true);
    fields.setMargin(new MarginInfo(true, true, true, false));
    fields.setSizeUndefined();

    // The view root layout
    VerticalLayout viewLayout = new VerticalLayout(fields);
    viewLayout.setSizeFull();
    viewLayout.setComponentAlignment(fields, Alignment.MIDDLE_CENTER);
    viewLayout.setStyleName(Reindeer.LAYOUT_BLUE);
    setCompositionRoot(viewLayout);
}

@Override
public void enter(ViewChangeEvent event) {
    // focus the username field when user arrives to the login view
    user.focus();
}

// Validator for validating the passwords
private static final class PasswordValidator extends
AbstractValidator<String> {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public PasswordValidator() {
        super("The password provided is not valid");
    }

    @Override
    protected boolean isValidValue(String value) {
        //
        // Password must be at least 8 characters long and contain at least
        // one number
        //
        if (value != null
                && (value.length() < 8 || !value.matches(".*\\d.*"))) {
            return false;
        }
        return true;
    }

    @Override
    public Class<String> getType() {
        return String.class;
    }
}

@Override
public void buttonClick(ClickEvent event) {

    //
    // Validate the fields using the navigator. By using validors for the
    // fields we reduce the amount of queries we have to use to the database
    // for wrongly entered passwords
    //
    if (!user.isValid() || !password.isValid()) {
        return;
    }

    String username = user.getValue();
    String password = this.password.getValue();

    //
    // Validate username and password with database here. For examples sake
    // I use a dummy username and password.
    //
    boolean isValid = username.equals("test@test.com")
            && password.equals("passw0rd");

    if (isValid) {

        // Store the current user in the service session
        getSession().setAttribute("user", username);

        // Navigate to main view
        getUI().getNavigator().navigateTo(MainView.NAME);//

    } else {

        // Wrong password clear the password field and refocuses it
        this.password.setValue(null);
        this.password.focus();

    }
}

private static final long serialVersionUID = 1L; public static final String NAME = "login"; private final TextField user; private final PasswordField password; private final Button loginButton; public SimpleLoginView() { setSizeFull(); // Create the user input field user = new TextField("User:"); user.setWidth("300px"); user.setRequired(true); user.setInputPrompt("Your username (eg. joe@email.com)"); user.addValidator(new EmailValidator( "Username must be an email address")); user.setInvalidAllowed(false); // Create the password input field password = new PasswordField("Password:"); password.setWidth("300px"); password.addValidator(new PasswordValidator()); password.setRequired(true); password.setValue(""); password.setNullRepresentation(""); // Create login button loginButton = new Button("Login", this); // Add both to a panel VerticalLayout fields = new VerticalLayout(user, password, loginButton); fields.setCaption("Please login to access the application. (test@test.com/passw0rd)"); fields.setSpacing(true); fields.setMargin(new MarginInfo(true, true, true, false)); fields.setSizeUndefined(); // The view root layout VerticalLayout viewLayout = new VerticalLayout(fields); viewLayout.setSizeFull(); viewLayout.setComponentAlignment(fields, Alignment.MIDDLE_CENTER); viewLayout.setStyleName(Reindeer.LAYOUT_BLUE); setCompositionRoot(viewLayout); } @Override public void enter(ViewChangeEvent event) { // focus the username field when user arrives to the login view user.focus(); } // Validator for validating the passwords private static final class PasswordValidator extends AbstractValidator<String> { /** * */ private static final long serialVersionUID = 1L; public PasswordValidator() { super("The password provided is not valid"); } @Override protected boolean isValidValue(String value) { // // Password must be at least 8 characters long and contain at least // one number // if (value != null && (value.length() < 8 || !value.matches(".*\\d.*"))) { return false; } return true; } @Override public Class<String> getType() { return String.class; } } @Override public void buttonClick(ClickEvent event) { // // Validate the fields using the navigator. By using validors for the // fields we reduce the amount of queries we have to use to the database // for wrongly entered passwords // if (!user.isValid() || !password.isValid()) { return; } String username = user.getValue(); String password = this.password.getValue(); // // Validate username and password with database here. For examples sake // I use a dummy username and password. // boolean isValid = username.equals("test@test.com") && password.equals("passw0rd"); if (isValid) { // Store the current user in the service session getSession().setAttribute("user", username); // Navigate to main view getUI().getNavigator().navigateTo(MainView.NAME);// } else { // Wrong password clear the password field and refocuses it this.password.setValue(null); this.password.focus(); } }

2）主视图如下：

public class MainView extends CustomComponent implements View { 

/**
 * 
 */
private static final long serialVersionUID = 1L;

public static final String NAME = "";

Label text = new Label();

Button logout = new Button("Logout", new Button.ClickListener() {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Override
    public void buttonClick(ClickEvent event) {

        // "Logout" the user
        getSession().setAttribute("user", null);

        // Refresh this view, should redirect to login view
        getUI().getNavigator().navigateTo(NAME);
    }
});

public MainView() {
    setCompositionRoot(new CssLayout(text, logout));
}

@Override
public void enter(ViewChangeEvent event) {
    // Get the user name from the session
    String username = String.valueOf(getSession().getAttribute("user"));

    // And show the username
    text.setValue("Hello " + username);
}

3）在2个视图之间导航的主类

/** * */ private static final long serialVersionUID = 1L; public static final String NAME = ""; Label text = new Label(); Button logout = new Button("Logout", new Button.ClickListener() { /** * */ private static final long serialVersionUID = 1L; @Override public void buttonClick(ClickEvent event) { // "Logout" the user getSession().setAttribute("user", null); // Refresh this view, should redirect to login view getUI().getNavigator().navigateTo(NAME); } }); public MainView() { setCompositionRoot(new CssLayout(text, logout)); } @Override public void enter(ViewChangeEvent event) { // Get the user name from the session String username = String.valueOf(getSession().getAttribute("user")); // And show the username text.setValue("Hello " + username); }

}

public class LoginUI extends UI {

在Tomcat中运行代码时，我收到以下错误：

` 

@WebServlet(value = "/*", asyncSupported = true)
@VaadinServletConfiguration(productionMode = false, ui = LoginUI.class)
public static class Servlet extends VaadinServlet {
}

@Override
protected void init(VaadinRequest request) {

    //
    // Create a new instance of the navigator. The navigator will attach
    // itself automatically to this view.
    //
    new Navigator(this, this);

    //
    // The initial log view where the user can login to the application
    //
    getNavigator().addView(SimpleLoginView.NAME, SimpleLoginView.class);//

    //
    // Add the main view of the application
    //
    getNavigator().addView(MainView.NAME,
            MainView.class);

    //
    // We use a view change handler to ensure the user is always redirected
    // to the login view if the user is not logged in.
    //
    getNavigator().addViewChangeListener(new ViewChangeListener() {

        @Override
        public boolean beforeViewChange(ViewChangeEvent event) {

            // Check if a user has logged in
            boolean isLoggedIn = getSession().getAttribute("user") != null;
            boolean isLoginView = event.getNewView() instanceof SimpleLoginView;

            if (!isLoggedIn && !isLoginView) {
                // Redirect to login view always if a user has not yet
                // logged in
                getNavigator().navigateTo(SimpleLoginView.NAME);
                return false;

            } else if (isLoggedIn && isLoginView) {
                // If someone tries to access to login view while logged in,
                // then cancel
                return false;
            }

            return true;
        }

        @Override
        public void afterViewChange(ViewChangeEvent event) {

        }
    });
}

@WebServlet(value = "/*", asyncSupported = true) @VaadinServletConfiguration(productionMode = false, ui = LoginUI.class) public static class Servlet extends VaadinServlet { } @Override protected void init(VaadinRequest request) { // // Create a new instance of the navigator. The navigator will attach // itself automatically to this view. // new Navigator(this, this); // // The initial log view where the user can login to the application // getNavigator().addView(SimpleLoginView.NAME, SimpleLoginView.class);// // // Add the main view of the application // getNavigator().addView(MainView.NAME, MainView.class); // // We use a view change handler to ensure the user is always redirected // to the login view if the user is not logged in. // getNavigator().addViewChangeListener(new ViewChangeListener() { @Override public boolean beforeViewChange(ViewChangeEvent event) { // Check if a user has logged in boolean isLoggedIn = getSession().getAttribute("user") != null; boolean isLoginView = event.getNewView() instanceof SimpleLoginView; if (!isLoggedIn && !isLoginView) { // Redirect to login view always if a user has not yet // logged in getNavigator().navigateTo(SimpleLoginView.NAME); return false; } else if (isLoggedIn && isLoginView) { // If someone tries to access to login view while logged in, // then cancel return false; } return true; } @Override public void afterViewChange(ViewChangeEvent event) { } }); }

} `

1 个答案:

答案 0 :(得分：2)

如果视图通过Navigator#addView(String viewName, Class<? extends View> viewClass)添加到导航器中，Vaadin的Navigator类会尝试通过反射来实例化其视图类。但在您的情况下，无法实例化类SimpleLoginView，因为您声明了它abstract。从视图类定义中删除分类器abstract，您的示例应该可以正常工作。

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