通过postValidate进行JSF跨字段验证，而无需在后备bean中按名称查找组件

任小云

2023-03-14

问题内容：

我正在构建一个登录表单复合组件。使用它的页面将传递一个事件处理程序，该处理程序将验证用户名和密码。通常，当我们通过进行跨字段验证时（不使用复合组件）postValidate，事件处理程序必须按名称查找字段的组件。验证者最好不要这样做，因为这些是应该抽象的组件的内部细节。

知道如何在postValidate不知道复合组件内部细节的情况下如何在处理程序中获取用户名和密码字段的转换值吗？

更新： 这样做的目的不是完全避免按名称查找组件，而是能够跨域验证复合组件的字段，而无需使用页面和/或Bean来了解内部组件。组件的详细信息。

问题答案：

可以做到的。在下面的代码中，特别注意postValidate复合组件中的事件和postValidate后备组件中的方法。请注意，它如何解析MethodExpression属性并调用传入的方法。

这是复合组件：

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:cc="http://java.sun.com/jsf/composite"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:p="http://primefaces.org/ui">

    <!-- Login form. -->
    <cc:interface componentType="com.example.LoginForm">
        <cc:attribute name="emailAddress" type="java.lang.String" required="true"/>
        <cc:attribute name="rememberMe" type="java.lang.Boolean" required="true"/>
        <cc:attribute name="checkCredentials"
                      method-signature="void checkCredentials(java.lang.String,java.lang.String,java.lang.String)"
                      shortDescription="Parameters are clientId, username and password. If credentials are invalid, attach a FacesMessage to the component specified by clientId."
                      required="true"/>
        <cc:attribute name="actionListener" method-signature="void actionListener()" required="true"/>
        <cc:attribute name="registerOutcome" type="java.lang.String" required="true"/>
        <cc:attribute name="recoverPasswordOutcome" type="java.lang.String" required="true"/>
        <cc:attribute name="headerTitle" type="java.lang.String" default="Sign In"/>
        <cc:attribute name="emailAddressLabel" type="java.lang.String" default="Email address:"/>
        <cc:attribute name="passwordLabel" type="java.lang.String" default="Password:"/>
        <cc:attribute name="rememberMeLabel" type="java.lang.String" default="Stay signed in on this machine"/>
        <cc:attribute name="loginLabel" type="java.lang.String" default="Sign In"/>
        <cc:attribute name="recoverPasswordLabel" type="java.lang.String" default="Forgot password?"/>
        <cc:attribute name="emailAddressRequiredMessage" type="java.lang.String" default="Email address required"/>
        <cc:attribute name="passwordRequiredMessage" type="java.lang.String" default="Password required"/>
        <cc:attribute name="registerLabel" type="java.lang.String" default="Register"/>
    </cc:interface>

    <cc:implementation>
        <h:outputStylesheet library="components/example/login-form" name="style.css"/>

        <div id="#{cc.clientId}">
            <h:form id="form">

                <f:event type="postValidate" listener="#{cc.postValidate}"/>

                <div style="margin-top:10px;">
                    <p:panel header="#{cc.attrs.headerTitle}" styleClass="loginPanel">
                        <div class="login-form_errorContainer">
                            <p:messages rendered="#{facesContext.maximumSeverity.ordinal ge 2}"/>
                        </div>
                        <h:panelGrid columns="3">
                            <h:outputText styleClass="login-form_label" value="#{cc.attrs.emailAddressLabel}"/>
                            <h:panelGroup styleClass="login-form_cell">
                                <h:inputText id="emailAddress"
                                             value="#{cc.attrs.emailAddress}"
                                             required="true"
                                             requiredMessage="#{cc.attrs.emailAddressRequiredMessage}"
                                             styleClass="login-form_field"
                                             immediate="true"/>
                            </h:panelGroup>
                            <h:panelGroup/>

                            <h:outputText styleClass="login-form_label" value="#{cc.attrs.passwordLabel}"/>
                            <h:panelGroup styleClass="login-form_cell">
                                <h:inputSecret id="password"
                                               value="#{cc.attrs.password}"
                                               required="true"
                                               requiredMessage="#{cc.attrs.passwordRequiredMessage}"
                                               styleClass="login-form_field"
                                               immediate="true"/>
                            </h:panelGroup>
                            <h:link styleClass="login-form_link" value="#{cc.attrs.recoverPasswordLabel}" outcome="#{cc.attrs.recoverPasswordOutcome}"/>

                            <h:panelGroup/>
                            <p:selectBooleanCheckbox value="#{cc.attrs.rememberMe}" itemLabel="#{cc.attrs.rememberMeLabel}" immediate="true"/>
                            <h:panelGroup/>

                            <h:panelGroup/>
                            <h:panelGroup>
                                <p:commandButton id="submitForm" value="#{cc.attrs.loginLabel}" actionListener="#{cc.attrs.actionListener}" update="form"/>
                                <span class="login-form_or">or</span>
                                <h:link styleClass="login-form_link" value="#{cc.attrs.registerLabel}" outcome="#{cc.attrs.registerOutcome}"/>
                            </h:panelGroup>
                            <h:panelGroup/>
                        </h:panelGrid>
                    </p:panel>
                </div>
            </h:form>
        </div>
    </cc:implementation>
</html>

支持组件：

@FacesComponent("com.example.LoginForm")
public class LoginFormComponent extends UIInput implements NamingContainer
{
    @Override
    protected Object getConvertedValue(FacesContext context, Object newSubmittedValue) throws ConverterException
    {
        UIInput emailAddressComponent = (UIInput) findComponent(EMAIL_ADDRESS_ID);
        UIInput passwordComponent = (UIInput) findComponent(PASSWORD_ID);
        String emailAddress = (String) emailAddressComponent.getValue();
        String password = (String) passwordComponent.getValue();
        return new LoginFormValue(emailAddress, password);
    }

    public void postValidate(ComponentSystemEvent e) {
        FacesContext ctx = getFacesContext();

        // Don't validate credentials if the username and/or password fields are invalid.
        if (!ctx.getMessageList(EMAIL_ADDRESS_ID).isEmpty() || !ctx.getMessageList(PASSWORD_ID).isEmpty())
        {
            return;
        }

        LoginFormValue value = (LoginFormValue) getConvertedValue(null, null);
        MethodExpression checkCredentials = (MethodExpression) getAttributes().get(CHECK_CREDENTIALS_ATTRIBUTE_NAME);
        checkCredentials.invoke(ctx.getELContext(), new Object[]{getClientId(), value.getEmailAddress(), value.getPassword()});
    }

    @Override
    public String getFamily()
    {
        return "javax.faces.NamingContainer";
    }

    public static final String CHECK_CREDENTIALS_ATTRIBUTE_NAME = "checkCredentials";
    public static final String EMAIL_ADDRESS_ID = "form:emailAddress";
    public static final String PASSWORD_ID = "form:password";
}

该LoginFormValue物品是否完整类：

public class LoginFormValue
{
    public LoginFormValue(String emailAddress, String password)
    {
        this.emailAddress = emailAddress;
        this.password = password;
    }

    public String getEmailAddress()
    {
        return emailAddress;
    }

    public String getPassword()
    {
        return password;
    }

    private String emailAddress;
    private String password;
}

使用登录表单的页面：

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:p="http://primefaces.org/ui"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ex="http://java.sun.com/jsf/composite/components/example">
    <h:head>
        <title></title>
    </h:head>
    <h:body>
        <ui:composition template="/WEB-INF/templates/myLayout.xhtml">
            <ui:define name="windowTitle">Sign In</ui:define>
            <ui:define name="body">

                <ex:login-form emailAddress="#{loginBean.emailAddress}"
                               rememberMe="#{loginBean.rememberMe}"
                               checkCredentials="#{loginBean.checkCredentials}"
                               actionListener="#{loginBean.submit()}"
                               recoverPasswordOutcome="recover-password"
                               registerOutcome="signup"/>

            </ui:define>
        </ui:composition>
    </h:body>
</html>

最后，页面的支持者：

@Named
@RequestScoped
public class LoginBean implements Serializable
{
    public String getEmailAddress()
    {
        return emailAddress;
    }

    public void setEmailAddress(String emailAddress)
    {
        this.emailAddress = emailAddress;
    }

    public boolean isRememberMe()
    {
        return rememberMe;
    }

    public void setRememberMe(boolean rememberMe)
    {
        this.rememberMe = rememberMe;
    }

    /** Action listener for login-form. Called after validation passes. */
    public void submit()
    {
        User user = userDao.findByEmailAddress(emailAddress);
        userRequestBean.login(user.getUserId());

        // Remember me
        if (!rememberMe)
        {
            return;
        }

        // Handle rememberMe here (create a cookie, etc.)
    }

    /** Called by the backing component's postValidate event handler */
    public void checkCredentials(String clientId, String emailAddress, String password)
    {
        if (!securityEjb.checkCredentials(emailAddress, password))
        {
            FacesMessage message = new FacesMessage(FacesMessage.SEVERITY_ERROR, "Incorrect email address/password", null);
            FacesContext ctx = FacesContext.getCurrentInstance();
            ctx.addMessage(clientId, message);
            ctx.renderResponse();
        }
    }

    private String emailAddress = "";

    private boolean rememberMe = true;

    @Inject
    private UserRequestBean userRequestBean;

    @EJB
    private SecurityEjb securityEjb;

    @EJB
    private UserDao userDao;

    @EJB
    private LoginCookieDao loginCookieDao;
}

通过postValidate进行JSF跨字段验证，而无需在后备bean中按名称查找组件

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