Jetty如何处理具有不同依赖关系的同一个类的类加载? [英] How Jetty handles class loading with same class with different dependencies?

问题描述

我想知道当多个依赖路径可以导致同一个类时，码头如何处理.

I want to know how jetty handles when multiple dependency paths which can lead to same class.

例如，

Jetty预先与JSTL-1.2一起打包，但是我添加了一个依赖项来加载JSTL-1.2.4.在编译时，如果我断点测试它在eclipse中下载源代码，它会在1.2.4版本中中断.

Jetty comes pre-packaged with JSTL-1.2, but I added a dependency to load JSTL-1.2.4. At compile time, if I breakpoint test it downloading the source code in eclipse, it breaks at 1.2.4 version.

当有两个版本的类时，我想知道将传递哪个版本来生成JSP的字节码，比如说某些基类 JstlCoreTlv 依赖(一个预先包装的，即具有码头的JSTL 1.2和来自Maven依赖项1.2.4的JSTL)

I want to know which version will be passed to generate byte code of a JSP, when there are two versions of classes, say some base class JstlCoreTlv in dependency (one pre-packaged, that is JSTL 1.2 with jetty and one passed from maven dependency 1.2.4)

简而言之，我想知道码头是怎么做的.我想知道码头如何优先考虑预包装与以后添加的依赖关系.即使该版本比预先打包的版本旧，它也会覆盖并引用附加的依赖项吗?

In brief, I want to know How jetty is doing it. I want to know how jetty prioritizes pre-packaged vs dependencies added later. Even if the version is older than that of pre-packaged one, will it override and refer to added dependencies?

在这种情况下，我从码头文件中获得的信息不多.非常感谢您的帮助

I couldn't get much in this context from jetty documentation. Help is much appreciated

推荐答案

servlet规范要求:

The servlet specification require that:

• WEB-INF/lib或WEB-INF/class中包含的类的优先级高于父类加载器(此处是jetty的类加载器)上的类.

来自

WEB-INF类可以替换Server类.

A WEB-INF class can replace a Server class.

这里的服务器类是j2ee标准的码头实现(来自

And the server class here is the jetty implementation of j2ee standard (code from jetty source code):

    /** Is the class a Server Class.
     * A Server class is a class that is part of the implementation of 
     * the server and is NIT visible to a webapplication. The web
     * application may provide it's own implementation of the class,
     * to be loaded from WEB-INF/lib or WEB-INF/classes 
     * @param clazz The fully qualified name of the class.
     * @return True if the class is a server class.
     */
    boolean isServerClass(Class<?> clazz);

您还可以通过调用以下命令来添加对服务器类的控制:

You can also add control of server class by calling:

• org.eclipse.jetty.webapp.WebAppContext.setServerClasses(String Array)
• org.eclipse.jetty.webapp.WebAppContext.addServerClass(String)

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