陷入 ManagedBeanPreProcessingException：处理托管 bean 时出现意外错误答案

【问题标题】：Stuck in ManagedBeanPreProcessingException : Unexpected error processing managed bean陷入 ManagedBeanPreProcessingException：处理托管 bean 时出现意外错误
【发布时间】：2011-06-26 01:27:42
【问题描述】：

谁能帮助我们解决这个问题？

我们正在尝试在我们的 JSF 应用程序中创建注册用户功能。我们希望用户在注册后立即登录。用户点击我是新客户commandLink后，出现了这个异常，不知道如何处理：

com.sun.faces.mgbean.ManagedBeanPreProcessingException: Unexpected error processing managed bean registerBean
    at com.sun.faces.mgbean.BeanManager.preProcessBean(BeanManager.java:394)
    at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:260)
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:86)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
    at com.sun.el.parser.AstIdentifier.getValue(AstIdentifier.java:99)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:158)
    at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
    at javax.faces.component.UIOutput.getValue(UIOutput.java:168)
    at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205)
    at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:338)
    at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:69)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
    at java.lang.Thread.run(Thread.java:662)
Caused by: com.sun.faces.mgbean.ManagedBeanPreProcessingException: Unexpected error processing managed property loginBean
    at com.sun.faces.mgbean.ManagedBeanBuilder.bake(ManagedBeanBuilder.java:117)
    at com.sun.faces.mgbean.BeanManager.preProcessBean(BeanManager.java:349)
    ... 50 more
Caused by: java.lang.NullPointerException
    at com.sun.faces.mgbean.ManagedBeanBuilder.bakeBeanProperty(ManagedBeanBuilder.java:350)
    at com.sun.faces.mgbean.ManagedBeanBuilder.bake(ManagedBeanBuilder.java:107)
    ... 51 more

这里是 LoginBean 和 RegisterBean：

@ManagedBean
@SessionScoped
public class LoginBean
{
    private String      username, password;
    private User        user;
    private UserManager um  = UserManager.getInstance();

    /**
     * 
     */
    public LoginBean()
    {
        super();
    }

    /**
     * @return the username
     */
    public String getUsername()
    {
        return username;
    }

    /**
     * @return the password
     */
    public String getPassword()
    {
        return password;
    }

    public void setUser(User user)
    {
        this.user = user;
        username = user.getUsername();
        password = user.getPassword();
    }

    /**
     * @return the user
     */
    public User getUser()
    {
        return user;
    }

    /**
     * @param username
     *             the username to set
     */
    public void setUsername(String username)
    {
        this.username = username;
    }

    /**
     * @param password
     *             the password to set
     */
    public void setPassword(String password)
    {
        this.password = password;
    }

    public String nextPage()
    {
        try
        {
            user = um.getUser(username, password);
        }
        catch (NoResultException e)
        {
            return "failure" + REDIRECT;
        }

        if (user instanceof Client)
            return "home_client" + REDIRECT;

        return "home_admin" + REDIRECT;

    }
}

@ManagedBean
@RequestScoped
public class RegisterBean
{
    private String      username, password, repassword, firstname, lastname, email, address, city, county, postcode, country, phone;

    @ManagedProperty(value = "#{loginBean}")
    private LoginBean   loginBean;

    // private UserManager um = UserManager.getInstance();

    public RegisterBean()
    {
    }

    /**
     * @return the username
     */
    public String getUsername()
    {
        return username;
    }

    /**
     * @return the password
     */
    public String getPassword()
    {
        return password;
    }

    /**
     * @return the repassword
     */
    public String getRepassword()
    {
        return repassword;
    }

    /**
     * @return the firstname
     */
    public String getFirstname()
    {
        return firstname;
    }

    /**
     * @return the lastname
     */
    public String getLastname()
    {
        return lastname;
    }

    /**
     * @return the email
     */
    public String getEmail()
    {
        return email;
    }

    /**
     * @return the address
     */
    public String getAddress()
    {
        return address;
    }

    /**
     * @return the city
     */
    public String getCity()
    {
        return city;
    }

    /**
     * @return the county
     */
    public String getCounty()
    {
        return county;
    }

    /**
     * @return the postcode
     */
    public String getPostcode()
    {
        return postcode;
    }

    /**
     * @return the country
     */
    public String getCountry()
    {
        return country;
    }

    /**
     * @return the phone
     */
    public String getPhone()
    {
        return phone;
    }

    /**
     * @return the user
     */
    public LoginBean getLoginBean()
    {
        return loginBean;
    }

    /**
     * @param username
     *             the username to set
     */
    public void setUsername(String username)
    {
        this.username = username;
    }

    /**
     * @param password
     *             the password to set
     */
    public void setPassword(String password)
    {
        this.password = password;
    }

    /**
     * @param repassword
     *             the repassword to set
     */
    public void setRepassword(String repassword)
    {
        this.repassword = repassword;
    }

    /**
     * @param firstname
     *             the firstname to set
     */
    public void setFirstname(String firstname)
    {
        this.firstname = firstname;
    }

    /**
     * @param lastname
     *             the lastname to set
     */
    public void setLastname(String lastname)
    {
        this.lastname = lastname;
    }

    /**
     * @param email
     *             the email to set
     */
    public void setEmail(String email)
    {
        this.email = email;
    }

    /**
     * @param address
     *             the address to set
     */
    public void setAddress(String address)
    {
        this.address = address;
    }

    /**
     * @param city
     *             the city to set
     */
    public void setCity(String city)
    {
        this.city = city;
    }

    /**
     * @param county
     *             the county to set
     */
    public void setCounty(String county)
    {
        this.county = county;
    }

    /**
     * @param postcode
     *             the postcode to set
     */
    public void setPostcode(String postcode)
    {
        this.postcode = postcode;
    }

    /**
     * @param country
     *             the country to set
     */
    public void setCountry(String country)
    {
        this.country = country;
    }

    /**
     * @param phone
     *             the phone to set
     */
    public void setPhone(String phone)
    {
        this.phone = phone;
    }

    public String register()
    {
        this.loginBean.setUser(new Client(username, password, new ContactDetails(firstname, lastname, email, address, city, county, postcode, country, phone)));

        return "home_client" + REDIRECT;
    }
}

这是来自 login.xhtml 的登录表单：

<h:form>
        Username: <h:inputText value="#{loginBean.username}" />
    <br />
        Password: <h:inputSecret value="#{loginBean.password}" />
    <br />
    <h:commandButton value="Login" action="#{loginBean.nextPage}" />
    <h:commandLink value="I'm a new client" action="register"></h:commandLink>
</h:form>

还有来自 register.xhtml 的注册表单：

<h:form>
    <h:outputText value="Inregistrare client nou"/>
    <br/>
    Username: <h:inputText value="#{registerBean.username}">
        <f:validator validatorId="registerUsernameValidator"></f:validator>
    </h:inputText>
    <br/>
    Parola: <h:inputSecret value="#{registerBean.password}"></h:inputSecret>
    <br/>
    Re-Parola: <h:inputSecret value="#{registerBean.repassword}"></h:inputSecret>
    <br/>
    <br/>

    Prenume: <h:inputText value="#{registerBean.firstname}"></h:inputText>
    <br/>
    Nume: <h:inputText value="#{registerBean.lastname}"></h:inputText>
    <br/>
    E-mail: <h:inputText value="#{registerBean.email}"></h:inputText>
    <br/>
    Adresa: <h:inputText value="#{registerBean.address}"></h:inputText>
    <br/>
    Oras: <h:inputText value="#{registerBean.city}"></h:inputText>
    <br/>
    Judet: <h:inputText value="#{registerBean.county}"></h:inputText>
    <br/>
    Cod postal: <h:inputText value="#{registerBean.postcode}"></h:inputText>
    <br/>
    Tara: <h:inputText value="#{registerBean.country}"></h:inputText>
    <br/>
    Telefon: <h:inputText value="#{registerBean.phone}"></h:inputText>
    <br/>
    <br/>
    <h:commandButton value="Inregistreaza-ma"


action="#{registerBean.register}"></h:commandButton>

我们自定义的 RegisterUsernameValidator：

public class RegisterUsernameValidator implements Validator
{
    UserManager um  = UserManager.getInstance();

    @Override
    public void validate(FacesContext context, UIComponent arg1, Object value) throws ValidatorException
    {
        String username = (String) value;
        if (!um.isUsernameAvailable(username))
        {
            FacesMessage facesMessage = new FacesMessage("Username indisponibil");
            FacesContext.getCurrentInstance().addMessage("Username indisponibil", facesMessage);
        }
    }
}

还有 faces-config.xml 中的验证部分：

<validator>
    <validator-id>registerUsernameValidator</validator-id>
    <validator-class>validation.RegisterUsernameValidator</validator-class>
</validator>

【问题讨论】：

标签： java jsf jsf-2

【解决方案1】：

com.sun.faces.mgbean.ManagedBeanPreProcessingException：处理托管bean registerBean时出现意外错误

这意味着在 RegisterBean 上直接处理 bean 属性由于开发人员错误（错误的配置、不可访问的属性、无效的属性类型等）而严重失败。问题的根本原因应该作为异常堆栈跟踪中的根本原因部分可见。由于您没有共享整个堆栈跟踪，因此很难说出究竟是什么失败了。

无论如何，只需阅读堆栈跟踪。答案就在里面。

更新：根据完整的堆栈跟踪：

原因：com.sun.faces.mgbean.ManagedBeanPreProcessingException：处理托管属性loginBean时出现意外错误
引起：java.lang.NullPointerException

loginBean 的托管属性无法在 registerBean 中设置。验证 RegisterBean 类中是否有 setter 并且它具有正确的签名。

public void setLoginBean(LoginBean loginBean) {
    this.loginBean = loginBean;
}

与具体问题无关，这个NullPointerException 应该真的是PropertyNotWritableException。您使用的是什么 JSF impl/version？

【讨论】：

我刚刚编辑了帖子，我无法从堆栈跟踪中找出问题所在。如果你能看一看，我将不胜感激。谢谢。
非常感谢，它现在可以使用该 setter 方法。我们正在使用 JSF 2.0。
不客气。是的，我已经看到了 JSF 2.0 特定的注释，但我对 specific impl（Mojarra、MyFaces 等）和版本（Mojarra 2.0.3 b03 等）更感兴趣。
@BalusC，我也在使用 Weblogic 12.1.3 提供的 JSF 2.0、Mojarra (javax.faces/2.1)，它抛出 NullPointException 而不是 PropertyNotWritableException。