小编Vit*_*nov的帖子

在Python中只初始化一次字段

我有文件services.py,其中包含某些类MyCache.MyCache的所有实例都应共享一个"缓存"字段,因此我将其设置为静态.为了初始化缓存,有一个加载它的静态方法.在应用程序的最开始,这个方法只调用一次.

问题是,当我从其他.py文件导入services.py并创建MyCache实例时 - 它打印出该缓存是空的!

如何修复它并使类的所有实例共享"缓存"字段而忽略它们的创建位置？

我不明白为什么会这样.请帮忙 :)

services.py:

class MyCache:
    cache = {}

    @staticmethod
    def initialize():
       MyCache.cache = load_from_file()
       print(len(MyCache.cache)) # prints 3

    def __init__(self):
       print(len(MyCache.cache)) # supposed to print 3, because initialize has been called earlier, but prints 0 when called from other_file.py

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main.py:

import services

if __name__ == '__main__':
    services.MyCache.initialize()

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other_file.py:

import services

services.MyCache().foo() # creates instance, prints 0 in MyCache.__init__

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python static

Vit*_*nov

2016 12-31

7
推荐指数

1
解决办法

723
查看次数

由于缺少jmxremote.access文件而禁用JMX身份验证,Tomcat 7无法启动

我的tomcat 7(在amazon-eu,java 1.7.0_51上托管)无法启动以下异常:

SEVERE: Catalina.start:org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:684)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:456)
Caused by: java.lang.IllegalArgumentException: jmxremote.access (No such file or directory)
        at javax.management.remote.rmi.RMIConnectorServer.start(RMIConnectorServer.java:372)
        at org.apache.catalina.mbeans.JmxRemoteLifecycleListener.createServer(JmxRemoteLifecycleListener.java:304)
        at org.apache.catalina.mbeans.JmxRemoteLifecycleListener.lifecycleEvent(JmxRemoteLifecycleListener.java:258)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
        at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
        at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:402)
        at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:347)
        at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:725)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        ... 7 more
Caused by: java.io.FileNotFoundException: jmxremote.access (No such file or directory)
        at java.io.FileInputStream.open(Native Method)
        at java.io.FileInputStream.<init>(FileInputStream.java:137)
        at java.io.FileInputStream.<init>(FileInputStream.java:96)
        at com.sun.jmx.remote.security.MBeanServerFileAccessController.propertiesFromFile(MBeanServerFileAccessController.java:294)
        at com.sun.jmx.remote.security.MBeanServerFileAccessController.<init>(MBeanServerFileAccessController.java:133)
        at javax.management.remote.rmi.RMIConnectorServer.start(RMIConnectorServer.java:370)
        ... …

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java tomcat jmx

Vit*_*nov

2014 02-26

6
推荐指数

1
解决办法

8956
查看次数

使跨度高度为外部 div 高度的 100%

下面是简单的html。目的是使左跨度高度为外部 div 高度的 100%，而不是将其文本垂直居中（即“abc”应与“ghi”成为一行）。屏幕截图（chrome，win10）上的结果：样式无效。

“row-eq-height”用于制作相同高度的列，并从这里复制。

<html>
<head>
    <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
    <style>
        .row-eq-height {
            display: -webkit-box;
            display: -webkit-flex;
            display: -ms-flexbox;
            display: flex;
        }
    </style>
</head>
<body>
<div class="container">
    <div style="display: table;">
        <div class="row row-eq-height">
            <div class="col-md-6" style="background-color: lightblue">
                <span style="height: 100%; display: inline-block; vertical-align: middle; background-color: lightgreen">abc</span>
            </div>
            <div class="col-md-6" style="background-color: lightcoral">
                def<br/>ghi<br/>jkl
            </div>
        </div>
    </div>
</div>
</body>
</html>

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