Java Applet 不缓存

本文介绍了Java Applet 不缓存的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我部署的 Java 小程序出现问题，该小程序拒绝缓存在 jvm 的粘性"缓存(或浏览器)中.出于某种原因，每次用户加载此小程序所在的页面时，jvm 都会从服务器重新下载 jar 文件，从而导致长时间延迟.

I'm having a problem with a Java applet I've deployed that is refusing to be cached in the jvm's "sticky" cache (or by the browser). For some reason every time a user loads the page this applet is on, the jvm re-downloads the jar file from the server which causes a long delay.

包含小程序的网页正在通过互联网访问，因此根据 Sun 的 Java 小程序文档我使用的是标签而不是或标签.

The webpage containing the applet is being accessed via the internet, so according to Sun's Java applet documentation I'm using an <applet> tag rather than an <object> or <embed> tag.

对调试或识别问题的任何帮助将不胜感激.

Any help debugging or identifying the problem would be much appreciated.

以下是我使用的完整小程序标签:

Below is the full applet tag I'm using:

<applet alt="Scanning Applet failed to load" archive="scanning.jar"
        code="scanning.scanlet.class" codebase="/java/" codetype="application/java"
        height="30" mayscript="True" name="scanlet" width="200">
    <param name="domain" value="192.168.12.23" />
    <param name="publishName" value="scan_attachment" />
    <param name="publishURL" value="http://192.168.12.23/draft/update/52" />
    <param name="curURL" value="http://192.168.12.23/draft/edit/52" />

Your browser is unable to process the Java &lt;APPLET&gt; tag needed to display this applet
<br />
One solution would be to download a better web browser like
<a href="http://www.mozilla.com/firefox">Mozilla's Firefox</a>

</applet>

推荐答案

我遇到了同样的问题，并发现了一个需要在服务器端应用的技巧.如果 jar 的 mime 类型不正确，它们似乎不会被缓存.请使用 application/java-archive mime 类型检查您的服务器回复.

I had the very same problem and found a trick that need to be applied server side. It seems that jars aren't cached if their mime type is incorrect. Please check your server reply using the application/java-archive mime type.

我发现的另一个问题与特定的 jar 有关.我的存档参数列出了许多 jar，但只有少数被缓存.我发现所有 jars 都缓存到一个特定的 jars，所有剩余的 jars 根本没有缓存.在加载小程序时，我在它的 Java 控制台中按下了5"，并在最后一个缓存的 jar 之后发现了这条消息: cache: signed entry missing from jar .我仍然不知道这个文件有什么问题，但我在存档参数列表的末尾移动了那个 jar.这修复"了问题.

Another problem I found is related to a specific jar. My archive parameter was listing many jars, but only a few were cached. I found that all jars upto a specific one where cached, all remaining jars weren't cached at all.While loading applet, I pressed "5" in its java console and found this message just after the last cached jar: cache: signed entry missing from jar . I still don't know what is wrong with this file, but I moved that jar at the end of the archive parameter list. This "fixed" the problem.

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