Spring Autowire停止为Tomcat类路径上的类工作 [英] Spring autowire stops working for classes on the Tomcat classpath

问题描述

在我的库FooLibrary.jar内部，Spring实例化了具有属性bars的类com.example.FooImpl.我有很多Bar实例，这些实例也由Spring实例化.一组条状线会自动连接到FooImpl中，如下所示:

Inside my library FooLibrary.jar Spring instantiates class com.example.FooImpl which has a property bars. I have lots of Bar instances also instantiated by Spring. A set of bars is autowired into FooImpl like this:

@Component
public class FooImpl {
  @Inject
  private Set<Bar> bars;

在独立应用程序中，Spring实例化Bar实例，实例化FooImpl实例，然后使用Bar的集合自动装配FooImpl.bars.可以.

In a standalone application, Spring instantiates the Bar instances, instantiates the FooImpl instances, and then autowires FooImpl.bars with the set of Bars. It works.

现在，我正在Tomcat内的webapp中运行相同的Spring配置. FooLibrary.jar位于WEB-INF/lib内部，并且所有内容均按上述概述继续工作.

Now I'm running the same Spring configuration in a webapp inside Tomcat. FooLibrary.jar is inside WEB-INF/lib, and everything continues to work as outlined above.

问题是该Web应用使用JavaCompiler，无法自动找到其依赖项来自动编译某些类除非我将该库放在启动Tomcat路径上.我将FooLibrary.jar添加到Tomcat类路径的那一刻(例如，在Eclipse内Tomcat的启动配置中，或者如果独立运行Tomcat，则假定startup.sh或setclasspath.bat)，自动装配停止工作.

The problem is that the web app automatically compiles somes classes using JavaCompiler, which can't find its dependencies for dynamically compiling unless I place that library on the startup Tomcat path. The minute I add FooLibrary.jar to the Tomcat classpath (e.g. in in the launch configuration of Tomcat inside Eclipse, or I presume startup.sh or setclasspath.bat if running Tomcat standalone), autowire stops working.

也就是说，当我的Web应用程序启动时，Spring将创建所有Bar实例，然后实例化FooImpl，但是从不将的集合自动关联到. 知道为什么吗?

That is, when my webapp starts up, Spring creates all the Bar instances, then instantiates FooImpl, but never autowires the set of Bars into FooImpl.bars. Any idea why?

(这与从Webapp类加载器启动Spring ContextLoaderListener有什么关系，但我想知道FooImpl和Bar实例是从Tomcat类加载器启动的吗?)

(Does it have something to do with the Spring ContextLoaderListener being started from the webapp classloader, but the FooImpl and Bar instances coming from the Tomcat classloader, I wonder?)

推荐答案

由于类型不兼容(例如，在多个类加载器中加载的类)，自动装配可能会失败.

Autowiring can fail due to incompatible types (e.g. classes loaded in multiple classloaders).

由于您已经将JAR放置在tomcat的启动类路径中，因此web应用程序也必须可见该JAR，而不必将JAR放置在WEB-INF/lib中.

Since you already place the JAR in tomcat's boot classpath, it must be visible to the webapp as well without you having to place the JAR in WEB-INF/lib.

您可以将依赖项范围provided设置为不让Maven放置在WEB-INF/lib中.

You can make the dependency scope provided to not have Maven place it in WEB-INF/lib.

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