小编Mah*_*leh的帖子

任何人都可以请教我在java +5中增强for循环和迭代器的优点是什么？

我有一个类,它有一个在xml中定义的init方法

<bean id="appStarter" class="com.myapp.myClass" init-method="init" destroy-method="destroy"/>

我的课:

public class myClass{

    private Thread t;

    public void init() {

             t = new Thread() {

                @Override
                public void run() {
                    while (true)
                        try {
                            doStuff();
                            Thread.sleep(1000);
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                }

            };
            t.start();
        }

public void destroy() {
        t.interrupt();
    }

}

当应用程序启动时,这些线程运行正常,一切正常,一段时间后我得到以下异常.

INFO: Illegal access: this web application instance has been stopped already.  Could not load com.sun.mail.imap.IMAPStore.  The eventual following stack trace is caused by an error thrown for debugging …

我正在尝试在swing应用程序中使用hibernate 3.5.1 final,这里是我正在使用的jar:

• 休眠核心3.5.1决赛
• 休眠-的EntityManager-3.5.1-决赛
• hibernate-jpa-2.0-api-1.0.0.Final
• 冬眠的注解-3.5.1-决赛
• hibernate-commons-annotations-3.2.0.Final
• dom4j的-1.6.1
• SLF4J-API-1.6.4
• SLF4J-log4j12-1.6.4

当我尝试运行该应用程序时,出现以下错误:

Failed to instantiate SLF4J LoggerFactory
Reported exception:
java.lang.NoClassDefFoundError: org/apache/log4j/Level
    at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
    at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:108)
    at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:279)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:252)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:265)
    at org.hibernate.cfg.Configuration.<clinit>(Configuration.java:165)
    at org.hibernate.ejb.Ejb3Configuration.<clinit>(Ejb3Configuration.java:127)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:54)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:48)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:32)
    at com.xeno.xecamp.desktopManagement.Main.main(Main.java:16)
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Level
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    ... 11 more
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Level
    at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
    at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:108)
    at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:279)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:252)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:265)
    at …

嗨伙计们尝试在tomcat上使用eclipse/linux运行我的应用程序时,我收到以下信息消息:

INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/lib/jvm/java-6-sun-1.6.0.20/jre/lib/amd64/server:/usr/lib/jvm/java-6-sun-1.6.0.20/jre/lib/amd64:/usr/lib/jvm/java-6-sun-1.6.0.20/jre/../lib/amd64:/usr/lib64/xulrunner-addons:/usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib

如何解决这个问题？

我有一个部门实体,其关系如下:

1. 许多部门可以在一个父部门:

   @ManyToOne
   @JoinColumn(name = "ik_parent_department_id")
   private Department parentDepartment;
   

   Run Code Online (Sandbox Code Playgroud)

2. 一个父部门可以有很多部门:

   @OneToMany(mappedBy = "parentDepartment")
   private Set<Department> children = new HashSet<Department>(0);
   

   Run Code Online (Sandbox Code Playgroud)

我想实现下一个:当我删除一个部门时,该部门所有子项的ik_parent_department_id参数都设置为null.任何想法如何做到这一点？

我只是想知道如何增加tomcat线程池中的线程数？以及设置最大值的数字,我不知道什么是合适的？

当尝试使用Oracle SQL Developer连接到我的数据库时,我收到错误:

ORA-28001密码已过期

如何在SQL Developer中更改密码？

问候所有我想让JQuery在两个函数之间休眠/等待一秒钟

$('#div1').hide();
//sleep or wait or for a sec 
$("#div2").show();

该怎么办？

我通过添加以下行来设置tomcat 7的堆大小 catalina.sh

export CATALINA_OPTS="-Xms512m -Xmx1024m"

然后停下来,启动了tomcat.但是当尝试使用命令jmap -heap获取堆大小时,我可以注意到内存不会改变:

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize      = 526385152 (502.0MB)
   NewSize          = 1048576 (1.0MB)
   MaxNewSize       = 4294901760 (4095.9375MB)
   OldSize          = 4194304 (4.0MB)
   NewRatio         = 2
   SurvivorRatio    = 8
   PermSize         = 16777216 (16.0MB)
   MaxPermSize      = 67108864 (64.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 99352576 (94.75MB)
   used     = 9643144 (9.196418762207031MB)
   free     = 89709432 (85.55358123779297MB)
   9.705982862487632% used
From Space:
   capacity = 4063232 (3.875MB)
   used     = 0 (0.0MB)
   free     = 4063232 …

我想在独立的应用程序中使用嵌入式德比的hibernate,我有一些问题:

1. 我需要什么罐子？
2. 什么是必要的休眠配置？
3. 还有其他必要的配置吗？
4. 查询/标准是否有任何问题/限制？

如果你也可以建议我这个方法的一些好的教程,这将是更好的,提前谢谢.