[英]How to grant applet permission to read system properties?
I have a Java applet that is trying to read the http.strictPostRedirect
System Property . 我有一个Java小程序正在尝试读取
http.strictPostRedirect
系统属性 。
The code is not mine (it's Java's; so i cannot change it). 该代码不是我的(它是Java的;因此我无法更改它)。 But you can find the code online:
但是您可以在线找到代码:
HttpURLConnection.java : HttpURLConnection.java :
if (method.equals("POST") && !Boolean.getBoolean("http.strictPostRedirect") && (stat!=307))
{
/* The HTTP/1.1 spec says that a redirect from a POST
* *should not* be immediately turned into a GET, and
* that some HTTP/1.0 clients incorrectly did this.
* Correct behavior redirects a POST to another POST.
* Unfortunately, since most browsers have this incorrect
* behavior, the web works this way now. Typical usage
* seems to be:
* POST a login code or passwd to a web page.
* after validation, the server redirects to another
* (welcome) page
* The second request is (erroneously) expected to be GET
*
* We will do the incorrect thing (POST-->GET) by default.
* We will provide the capability to do the "right" thing
* (POST-->POST) by a system property, "http.strictPostRedirect=true"
*/
...
}
The basic failure comes from calling: 基本的失败来自于调用:
Boolean.getBoolean("http.strictPostRedirect")
Which has caused a lot of people grief . 这引起了很多人的悲伤 。 Apparently i'm not allowed to read the
http.strictPostRedirect
System Property. 显然,我不允许阅读
http.strictPostRedirect
系统属性。 Trying to read it throws an AccessControlException : 尝试读取它会引发AccessControlException :
java.security.AccessControlException: access denied (java.util.PropertyPermission http.strictPostRedirect read)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPropertyAccess(Unknown Source)
at java.lang.System.getProperty(Unknown Source)
at java.lang.Boolean.getBoolean(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.followRedirect(Unknown Source)
So, if i don't have permission to read permission to a System Property : 因此,如果我没有权限读取 系统属性的权限:
How do i get read permission to a system property?
如何获得对系统属性的读取权限?
There obviously must be a setting that gives me permission to read a system property, otherwise Sun wouldn't have code that transparently tries to access it. 显然,必须有一个设置可以授予我读取系统属性的权限,否则Sun不会拥有透明地尝试访问它的代码。
Is it a machine world-wide setting? 它是世界范围内的机器吗? Is it a domain-wide setting?
它是域范围的设置吗? Is it a machine-wide setting?
它是机器范围的设置吗? Is it a per-user setting?
是每个用户的设置吗? Is it a per-applet setting?
是每个小程序的设置吗? Is it a per-invocation setting?
它是按调用设置的吗? Is it a setting tied to a particular version of the Java Runtime Engine ?
它是与特定版本的Java Runtime Engine绑定的设置吗?
tl;dr : How make not crash? tl; dr :如何使不崩溃?
Java does have a list of system properties than at applet cannot read : Java确实有一个系统属性列表,比applet无法读取 :
java.class.path
java.home
user.dir
user.home
user.name
My system property , http.strictPostRedirect
, is not on that list. 我的系统属性
http.strictPostRedirect
不在该列表中。 So why can't i read it? 那我为什么看不懂呢?
HttpURLConnection.java
The 'fix' here is to digitally sign the applet, then convince the user to OK the code when prompted. 这里的“解决方案”是对小程序进行数字签名,然后在出现提示时说服用户确定代码。
Java does have a list of system properties than at applet cannot read:
Java确实有一个系统属性列表,比applet无法读取:
- java.class.path
java.class.path
- java.home
java.home
- user.dir
user.dir来
- user.home
的user.home
- user.name
用户名
My system property, http.strictPostRedirect, is not on that list.
我的系统属性http.strictPostRedirect不在该列表中。 So why can't i read it?
那我为什么看不懂呢?
That is the 'short list' of properties that a sand-boxed app. 这是沙盒应用程序的属性的“简短列表”。 cannot read.
无法阅读。 There are also many more.
还有很多。 EG nothing under
user
is permitted 1 . EG禁止
user
1 。 Just consider those to be 'typical'. 只考虑那些是“典型的”。
user
properties in a sand-boxed app. user
属性的输出。 Name Value
user.country unknown
user.dir unknown
user.home unknown
user.language unknown
user.name unknown
user.timezone unknown
user.variant unknown
There obviously must be a setting that gives me permission to read a system property, otherwise Sun wouldn't have code that transparently tries to access it.
显然,必须有一个设置可以授予我读取系统属性的权限,否则Sun不会拥有透明地尝试访问它的代码。
True. 真正。 See the fix above.
请参阅上面的修复程序。
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