在构造函数中泄漏这个

Question

这个Controller类是一个单身人士,这似乎是一个允许安全传递this到的特殊情况Controller.

Netbeans给出了

配置"在构造函数中传递可疑参数"提示

对于controller.addObserver(this);这点让我问更好的方法是什么,虽然我收集这不是一个好方法.

package net.bounceme.dur.usenet.swing;

import java.util.Observable;
import java.util.Observer;
import java.util.logging.Logger;
import javax.mail.Folder;
import javax.swing.ListModel;
import net.bounceme.dur.usenet.controller.Controller;
import net.bounceme.dur.usenet.controller.MessageBean;
import net.bounceme.dur.usenet.controller.MessagesDefaultListModel;

public class MessageSelect extends javax.swing.JPanel implements Observer {

    private static final Logger LOG = Logger.getLogger(MessageSelect.class.getName());
    private Controller controller = Controller.getInstance();
    private ListModel messages = new MessagesDefaultListModel();
    private MessageBean messageBean = new MessageBean();

    @SuppressWarnings("unchecked")
    public MessageSelect() {
        controller.addObserver(this);
        initComponents();
        messagesJList.setPrototypeCellValue("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
    }

Answer 1

当对象尚未完全构造时,您将传递this给外部类(Controller).Controller然后可以在构造尚未完成时引用您的对象.

大多数人通过使用工厂方法解决这个问题,工厂方法首先创建对象,然后从this外部传递.

// private to force clients to use the static factory method
private MessageSelect() {
  initComponents();
  messagesJList.setPrototypeCellValue("xxx");
}

public static MessageSelect createInstance() {
  MessageSelect instance = new MessageSelect();
  instance.controller.addObserver(instance);
  return instance;
}

看看这篇关于安全对象构造的优秀Brian Goetz文章.