记录器，从@Inject 转换为生产者

Question

我有实施类似例如登录接口故障的简单与JSF 2.1 CRUD Web应用程序，PrimeFaces 3.5，EJB 3.1，JPA（ORM）/ EclipseLink的，JAAS中，MySQL 在TomEE的邮件列表，我被告知，我LoginController.java我正在尝试注入 Logger，但 Logger 注入不受 CDI 管理。有人告诉我改用生产者。不知道它是什么，我在互联网上搜索并找到了这个示例 但是我仍然不满意它，所以请解释我必须修改什么才能为记录器实现生产者。

登录控制器.java

package controller;

import util.DateUtility;

import java.io.IOException;
import java.io.Serializable;
import java.security.Principal;
import java.util.logging.Level;
import java.util.logging.Logger;


import javax.enterprise.context.SessionScoped;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;
import javax.inject.Inject;
import javax.inject.Named;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * Login Controller class allows only authenticated users to log in to the web
 * application.
 *
 * @author Emre Simtay <emre@simtay.com>
 */
@Named
@SessionScoped

public class LoginController implements Serializable {

    @Inject
    private transient Logger logger;
    private String username;
    private String password;

    /**
     * Creates a new instance of LoginController
     */
    public LoginController() {
        System.out.println("test");
    }

    //  Getters and Setters
    /**
     * @return username
     */
    public String getUsername() {
        return username;
    }

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

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

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

    /**
     * Listen for button clicks on the #{loginController.login} action,
     * validates the username and password entered by the user and navigates to
     * the appropriate page.
     *
     * @param actionEvent
     */
    public void login(ActionEvent actionEvent) {
        System.out.println("CONSOLE PRINT TEST");

        FacesContext context = FacesContext.getCurrentInstance();
        HttpServletRequest request = (HttpServletRequest) context.getExternalContext().getRequest();
        try {
            String navigateString = "";
            // Checks if username and password are valid if not throws a ServletException
            request.login(username, password);
            // gets the user principle and navigates to the appropriate page
            Principal principal = request.getUserPrincipal();
            if (request.isUserInRole("Administrator")) {
                navigateString = "/admin/AdminHome.xhtml";
            } else if (request.isUserInRole("Manager")) {
                navigateString = "/manager/ManagerHome.xhtml";
            } else if (request.isUserInRole("User")) {
                navigateString = "/user/UserHome.xhtml";
            }
            try {
                logger.log(Level.INFO, "User ({0}) loging in #" + DateUtility.getCurrentDateTime(), request.getUserPrincipal().getName());
                context.getExternalContext().redirect(request.getContextPath() + navigateString);
            } catch (IOException ex) {
                logger.log(Level.SEVERE, "IOException, Login Controller" + "Username : " + principal.getName(), ex);
                context.addMessage(null, new FacesMessage("Error!", "Exception occured"));
            }
        } catch (ServletException e) {
            logger.log(Level.SEVERE, e.toString());
            context.addMessage(null, new FacesMessage("Error!", "The username or password you provided does not match our records."));
        }
    }

    /**
     * Listen for logout button clicks on the #{loginController.logout} action
     * and navigates to login screen.
     */
    public void logout() {

        HttpSession session = (HttpSession) FacesContext.getCurrentInstance().getExternalContext().getSession(false);
        HttpServletRequest request = (HttpServletRequest) FacesContext.getCurrentInstance().getExternalContext().getRequest();
        logger.log(Level.INFO, "User ({0}) loging out #" + DateUtility.getCurrentDateTime(), request.getUserPrincipal().getName());
        if (session != null) {
            session.invalidate();
        }
        FacesContext.getCurrentInstance().getApplication().getNavigationHandler().handleNavigation(FacesContext.getCurrentInstance(), null, "/Login.xhtml?faces-redirect=true");
    }
}

Answer 1

当您使用 时@Inject，CDI 会尝试为您创建所请求类型的实例。最简单的解决方案：它调用默认构造函数并返回该实例。

问题java.util.logging.Logger：它没有可见的默认构造函数。因此，您必须通过向类路径添加 Producer 来告诉 CDI 如何满足依赖关系。尽管使用 @JohnAment 建议的焊接记录器也是我的首选解决方案，但考虑到您目前的知识状态，如果您从添加自己的生产者开始，它可能最适合您。

所以在你的控制器旁边，创建一个新的类（添加包，导入，......你自己）

public class LoggerProducer {
   @Produces
   public Logger getLogger(InjectionPoint p) {
     return Logger.getLogger(p.getClass().getCanonicalName());
   }
}

这告诉 CDI 容器：每当您需要注入 时java.util.logging.Logger，请使用此方法通过获取需要该记录器引用的类的 fqn 名称来创建一个。

这应该可以解决您的问题。一旦你有了这个想法，想想你是否真的想要/需要使用 java.util.logging 或者你是否想要切换到slf4j。在这种情况下，修改您的控制器导入，删除您刚刚编写的 LoggerProducer 并将焊接记录器jar导入您的部署。