我正在尝试为单个 session bean 提供一个基本模板。然后,我举了《计数器的架构》中包含的例子:
https://docs.oracle.com/javaee/7/tutorial/ejb-basicexamples002.htm
但是,在运行示例时,我无法打印 count.hitCount 的值。
我发现访问变量时的常见问题是没有 getter。例如,在 index.html 中:
<ui:define name="title">
This page has been accessed #{count.hitCount} time(s).
</ui:define>
但是,在 Count.java 中包含 getter getHitCount():
@Named
@SessionScoped
public class Count implements Serializable {
@EJB
private CounterBean counterBean;
private int hitCount;
public Count() {
this.hitCount = 0;
}
public int getHitCount() {
hitCount = counterBean.getHits();
return hitCount;
}
public void setHitCount(int newHits) {
this.hitCount = newHits;
}
最后,CounterBean.java增加变量:
@Singleton
public class CounterBean {
private int hits = 1;
// Increment and return the number of hits
public int getHits() {
return hits++;
}
}
感谢您的帮助和评论,我们非常感激。
最佳答案
带有显示次数计数器的 Facelet:
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<h:head>
<title>Facelet Title</title>
</h:head>
<h:body>
This page displayed #{counterController.hitCount} times.
</h:body>
</html>
CounterController
是一个 @RequestScoped
bean,用于在其 @PostConstruct
方法中递增 CounterBean.hitCount
:
package x;
import javax.annotation.PostConstruct;
import javax.ejb.EJB;
import javax.inject.Named;
import javax.enterprise.context.RequestScoped;
@Named( value = "counterController" )
@RequestScoped
public class counterController
{
@EJB
private CounterBean counterBean;
@PostConstruct
public void initialize()
{
counterBean.incHitCount();
}
public int getHitCount()
{
return counterBean.getHitCount();
}
public CounterController()
{
}
}
CounterBean
是一个用于存储 hitCount 的 @Singleton
EJB。 @StartUp
注释将其作为一个急切构建的 bean(在应用程序启动时创建,在接受任何客户端请求之前):
package x;
import javax.ejb.Singleton;
import javax.ejb.Startup;
import lombok.Data;
@Singleton
@Startup
public class CounterBean
{
private int hitCount;
public int getHitCount()
{
return hitCount;
}
public void incHitCount()
{
hitCount++;
}
public CounterBean()
{}
}
关于java - 单例 session Bean,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43987676/