英文:
How can we overwrite java.base/java.lang.Integer from OpenJDK 11 using --patch-module?
问题
在JDK-8中,我们可以编译已更改的java.lang类并重建rt.jar
。然后,我们可以通过在引导类路径中添加-Xbootclasspath:<yourpathto>/rt.jar
来覆盖java.lang类文件。通过这样做,例如,我们可以使java.lang.Integer在测试目的下变为非final。
在JDK-11中,情况不同。修补是通过--patch-modules
进行的,但我无法使其工作。我已经执行了以下操作:
- 删除了java.base模块的final修饰符并从openjdk-11源代码重新编译了java.base模块。
- 添加了
--patch-module java.base=<path-to-my-compiled-java.base-directory>
。 - 仍然出现
error: cannot inherit from final Integer
错误。可能我们不能再覆盖JDK源文件的类声明了?这会很奇怪。 - 我还尝试将这些类文件添加到一个jar中,并尝试将所有可能的根目录传递给
--patch-module
参数。 - 我尝试从编译的
java.base
目录中删除模块package-info.class
,并尝试使用--add-opens
显式添加java.base.java.lang.Integer
。
文档对于这种特定的用法并不是很清楚。
来自Maven的完整javac命令(我尝试过javac和maven-compiler-plugin):
javac -d ./target/classes -classpath <classpathfiles> -sourcepath <sourcefiles> -s ./target/generated-sources/annotations -g -nowarn -target 11 -source 11 -encoding UTF-8 --patch-module=java.base=../runtimejar/mods/src/java.base -Xplugin:Manifold
(为了可读性,缩短了路径名等)
我在这里漏掉了什么?为什么我不能像这样修改java.base/java.lang.Integer
?
英文:
In the JDK-8, we could compile our changed java.lang classes and reconstruct the rt.jar
. Then we could overwrite java.lang classfiles by augmenting the bootclasspath with -Xbootclasspath:<yourpathto>/rt.jar
. Doing this, we could for example make java.lang.Integer be non-final for testing purposes.
In JDK-11, this is different. Patching is done via --patch-modules
and I can't get it to work. I have done the following:
- Remove the final modifier and recompiled the java.base module from the openjdk-11 source
- Added the
--patch-module java.base=<path-to-my-compiled-java.base-directory>
- It still fails on
error: cannot inherit from final Integer
. Possibly we can't overwrite the class declarations of JDK source files anymore? That would be strange. - I've also tried adding these classfiles to a jar and tried to pass all possible root directories to the
--patch-module
argument - I've tried removing the module
package-info.class
from the compiledjava.base
directory and tried explicitly addingjava.base.java.lang.Integer
with--add-opens
The docs aren't really clear on this particular usage.
The entire javac command from maven (I have tried both javac and the maven-compiler-plugin):
javac -d ./target/classes -classpath <classpathfiles> -sourcepath <sourcefiles> -s ./target/generated-sources/annotations -g -nowarn -target 11 -source 11 -encoding UTF-8 --patch-module=java.base=../runtimejar/mods/src/java.base -Xplugin:Manifold
(Shortened path names etc. for readability)
What am I missing here? Why can't I modify java.base/java.lang.Integer
like this?
答案1
得分: 3
以下是翻译好的内容:
来自Project Jigsaw的示例模型适用于您的用例。请注意在javac和java中使用--patch-module。
--patch-module
从Doug Lea的CVS中签出java.util.concurrent类的开发人员将用于编译源文件并使用-Xbootclasspath/p部署这些类。
-Xbootclasspath/p已被移除,其模块替代品是选项--patch-module,用于覆盖模块中的类。它还可以用于增加模块的内容。--patch-module选项也受javac支持,以便将代码编译为模块的一部分。
以下是一个示例,编译了java.util.concurrent.ConcurrentHashMap的新版本,并在运行时使用它:
javac --patch-module java.base=src -d mypatches/java.base \
src/java.base/java/util/concurrent/ConcurrentHashMap.java
java --patch-module java.base=mypatches/java.base ...
确保您的源路径与--patch-module目录对齐,即src/java.base/java/lang/Integar.java文件是否存在,并且是否在您的源路径中?
更新
以下是一个演示如何对java.lang.Integer进行影响的示例项目:链接
编译:
javac --patch-module java.base=src -d mypatches/java.base src/java.base/java/lang/Integer.java
javac --patch-module java.base=mypatches/java.base -d target src/main/java/com/example/MyInteger.java src/main/java/com/example/RunMe.java
运行:
java --patch-module java.base=mypatches/java.base -classpath target com.example.RunMe
英文:
The example from Project Jigsaw models your use-case. Note the use of --patch-module for both javac and java.
>### --patch-module
>
>Developers that checkout java.util.concurrent classes from Doug Lea's CVS will be used to compiling the source files and
> deploying those classes with -Xbootclasspath/p.
>
> -Xbootclasspath/p has been removed, its module replacement is the option --patch-module to override classes in a module. It can also be
> used to augment the contents of module. The --patch-module option is
> also supported by javac to compile code "as if" part of the module.
>
> Here's an example that compiles a new version of
> java.util.concurrent.ConcurrentHashMap and uses it at run-time:
>
> javac --patch-module java.base=src -d mypatches/java.base \
> src/java.base/java/util/concurrent/ConcurrentHashMap.java
>
> java --patch-module java.base=mypatches/java.base ...
>
Check that your sourcepath aligns with your --patch-module directory i.e., is there a file src/java.base/java/lang/Integar.java and is it in your sourcepath?
Update
Here is a sample project that demonstrates how to shadow java.lang.Integer: https://dl.dropbox.com/s/6swet2k89vukxbm/patch.zip
Compile:
javac --patch-module java.base=src -d mypatches/java.base src/java.base/java/lang/Integer.java
javac --patch-module java.base=mypatches/java.base -d target src/main/java/com/example/MyInteger.java src/main/java/com/example/RunMe.java
Run:
java --patch-module java.base=mypatches/java.base -classpath target com.example.RunMe
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