Converter @FacesConverter(forClass=[someClass.class]) 可以实现为@Singleton @Lock(READ) 吗？

Question

为了在我的应用程序中删除“静态”声明（以帮助 JVM 的 GC），我从下面的 Converter 类的定义中删除了“静态”。这导致了下面臭名昭著的错误：

Apr 13, 2013 4:10:38 AM org.apache.myfaces.application.ApplicationImpl internalCreateConverter
SEVERE: Could not instantiate converter jsf.CustomerController$CustomerControllerConverter
java.lang.InstantiationException: jsf.CustomerController$CustomerControllerConverter
    at java.lang.Class.newInstance0(Unknown Source)
    at java.lang.Class.newInstance(Unknown Source)
    at org.apache.myfaces.application.ApplicationImpl.internalCreateConverter(ApplicationImpl.java:1626)
    at org.apache.myfaces.application.ApplicationImpl.createConverter(ApplicationImpl.java:1545)
    at javax.faces.application.ApplicationWrapper.createConverter(ApplicationWrapper.java:158)

我认为“静态”是必要的，因为每个应用程序只创建一个类的副本。正确的？那么，我可以将类定义为 @Singleton @Lock(READ) 来解决问题吗？

根据 NetBeans 生成的 JSF 控制器/bean 代码，转换器通常定义在与控制器或 @ManagedBean 相同的 .java 文件中。老实说，我“不想”在 xhtml 中使用 addConverter() 或 converterId="..." 。我更喜欢使用@FacesConverter，因为它在整个应用程序中都对我有用。

package jsf;

import jpa.entities.Customer;
import jpa.session.CustomerFacade;

import java.io.Serializable;
import javax.ejb.EJB;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;

@ManagedBean(name = "customerController")
@RequestScoped
public class CustomerController implements Serializable {

    @EJB
    private jpa.session.CustomerFacade ejbFacade;

    public CustomerController() {
    }

    @FacesConverter(forClass = Customer.class)
    public class CustomerControllerConverter implements Converter {

        public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
            if (value == null || value.length() == 0) {
                return null;
            }
            /*
             * 2012-07-10 when user enters invalid/incomplete value (e.g. "irene", see below) in AutoComplete
             *
            WARNING: For input string: "irene"
            java.lang.NumberFormatException: For input string: "irene"
                    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
                    at java.lang.Integer.parseInt(Integer.java:492)
                    at java.lang.Integer.valueOf(Integer.java:582)
                    at jsf.pointOfContact.pf_PointOfContactController$PointOfContactControllerConverter.getKey(pf_PointOfContactController.java:1625)
                    at jsf.pointOfContact.pf_PointOfContactController$PointOfContactControllerConverter.getAsObject(pf_PointOfContactController.java:1620)
                    at org.primefaces.component.autocomplete.AutoCompleteRenderer.getConvertedValue(AutoCompleteRenderer.java:529)
                    at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)
                    at javax.faces.component.UIInput.validate(UIInput.java:960)
             *
             */
            try {
                Integer test = getKey(value);
            } catch (java.lang.NumberFormatException e) {
                return null;
            }
            CustomerController controller = (CustomerController) facesContext.getApplication().getELResolver().
                    getValue(facesContext.getELContext(), null, "customerController");
            return controller.ejbFacade.find(getKey(value));
        }

        java.lang.Integer getKey(String value) {
            java.lang.Integer key;
            key = Integer.valueOf(value);
            return key;
        }

        String getStringKey(java.lang.Integer value) {
            StringBuffer sb = new StringBuffer();
            sb.append(value);
            return sb.toString();
        }

        public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
            if (object == null) {
                return null;
            }
            if (object instanceof Customer) {
                Customer o = (Customer) object;
                return getStringKey(o.getCustomerId());
            } else {
                throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + Customer.class.getName());
            }
        }
    }
}

请指教。

另外，当有人在 stackoverflow.com 上回答我的问题时，请告诉我如何接收电子邮件通知。

谢谢！

Answer 1

答案是肯定的，在 JNDI 查找的帮助下。

我刚刚从 JSF @RequestScoped CustomerController 中删除了 CustomerControllerConverter，创建了转换器类，用 @Singleton @Lock(READ) 标记它，并通过 JNDI 查找引用了 @Stateless EJB。见下文。

package converter;

import java.util.concurrent.TimeUnit;

import javax.ejb.AccessTimeout;
import javax.ejb.Lock;
import javax.ejb.LockType;
import javax.ejb.Singleton;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;

import javax.naming.InitialContext;

import jpa.entities.Customer;
import jpa.session.CustomerFacade;


/**
 *
 * @author Administrator
 */
@Singleton
@Lock(LockType.READ)
@AccessTimeout(value = 1, unit = TimeUnit.MINUTES)
@FacesConverter(forClass = Customer.class)
public class CustomerConverter implements Converter {

    public CustomerConverter() {

    }

    public Object getAsObject(FacesContext facesContext, UIComponent component, String value) {
        if (value == null || value.length() == 0) {
            return null;
        }
        /*
         * 2012-07-10 when user enters invalid/incomplete value (e.g. "irene", see below) in AutoComplete
         *
        WARNING: For input string: "irene"
        java.lang.NumberFormatException: For input string: "irene"
                at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
                at java.lang.Integer.parseInt(Integer.java:492)
                at java.lang.Integer.valueOf(Integer.java:582)
                ...
                ...
                at org.primefaces.component.autocomplete.AutoCompleteRenderer.getConvertedValue(AutoCompleteRenderer.java:529)
                at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)
                at javax.faces.component.UIInput.validate(UIInput.java:960)
         *
         */
        try {
            Integer test = getKey(value);
        } catch (java.lang.NumberFormatException e) {
            return null;
        }
        Object object = null;
        CustomerFacade ejbFacade;
        try {
            InitialContext ic = new InitialContext();
            ejbFacade = (CustomerFacade) ic.lookup("java:global/appWARFileNameOrAppContextName/CustomerFacade");
            if (ejbFacade == null) {
                System.err.println("CustomerConverter.getAsObject(): ejbFacade = null)");
                return null;
            }
        } catch (Exception e) {
            System.err.println("CustomerConverter.getAsObject(): error on JNDI lookup of CustomerFacade");
            e.printStackTrace();
            return null;
        }
        try {
            object = ejbFacade.find(getKey(value));
        } catch (Exception e) {
            System.err.println("CustomerConverter.getAsObject(): error on ejbFacade.find(getKey(value))");
            e.printStackTrace();
            return null;
        }
        return object;
    }

    java.lang.Integer getKey(String value) {
        java.lang.Integer key;
        key = Integer.valueOf(value);
        return key;
    }

    String getStringKey(java.lang.Integer value) {
        StringBuffer sb = new StringBuffer();
        sb.append(value);
        return sb.toString();
    }

    public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
        if (object == null) {
            return null;
        }
        if (object instanceof Customer) {
            Customer o = (Customer) object;
            return getStringKey(o.getCustomerId());
        } else {
            throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected type: " + Customer.class.getName());
        }
    }
}

经验教训：无法通过以下方式引用或实例化 ejbFacade：

@注入， @EJB， 豆类管理器

参考资料：

Oracle 博客

1. Ken Saks's Blog: Application-specified Portable JNDI Names
2. Ken Saks's Blog: Portable Global JNDI Names

TomEE JavaEE 示例 - 引用 EJB

1. Injection Of Ejbs
2. Lookup Of Ejbs with Descriptor
3. Lookup Of Ejbs

最后，我不得不参考 Glassfish 的 server.log 文件，即参考实现 (RI)，以查看我的 @Stateless EJB 的 JNDI 查找路径示例，因为我过去使用过 Glassfish。 :)

更新：

您还可以在 TomEE/catalina 日志中找到可移植的全局 JNDI 名称。如下所示。

Apr 13, 2013 10:00:58 AM org.apache.openejb.assembler.classic.JndiBuilder bind
INFO: Jndi(name=CustomerFacadeLocalBean) --> Ejb(deployment-id=CustomerFacade)

Apr 13, 2013 10:00:58 AM org.apache.openejb.assembler.classic.JndiBuilder bind
INFO: Jndi(name=global/webApp/CustomerFacade!jpa.session.CustomerFacade) --> Ejb(deployment-id=CustomerFacade)

Apr 13, 2013 10:00:58 AM org.apache.openejb.assembler.classic.JndiBuilder bind
INFO: Jndi(name=global/webApp/CustomerFacade) --> Ejb(deployment-id=CustomerFacade)

全局 JNDI 名称中的“webApp”可能是您的 WAR 文件名的名称，也可能是 EJB JAR 文件名等...

希望这对其他人有所帮助！