getResourceAsStream在一种情况下返回null，而不是另一种情况，具有相同的类路径(getResourceAsStream returns null in one case but n

getResourceAsStream在一种情况下返回null，而不是另一种情况，具有相同的类路径(getResourceAsStream returns null in one case but not another, with same classpaths)

我有两个相同应用的衍生物，比如版本（A）和（B）。 它们各自包含项目：（1）test-data-war，其具有target/test-classes/log4j.properties ，以及（2）test-kernel，其具有target/test-classes/log4j.properties和target/test-classes/test.properties 。

当我在（1）中运行特定的jUnit测试时，它调用（2）中的方法调用Thread.currentThread().getContextClassLoader().getResourceAsStream(resourceName); 在（A）中， resourceName为“log4j.properties”，结果不为null，路径为（1），但resourceName为“test.properties”，则为null。 在（B）中， resourceName为“log4j.properties”，它不是null，路径在（1）中，而resourceName是“test.properties”，它不是null，路径在（2）中。

为什么是Thread.currentThread().getContextClassLoader().getResourceAsStream("test.properties"); 在（A）中为null？ 起初，我认为类路径可能不同，但它们对于（1）和（2）都是相同的。

编辑：这是.classpath文件的样子（1）：

<?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" output="target/classes" path="src/main/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="src" output="target/test-classes" path="src/test/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" pat h="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER"> <attributes> <attribute name="maven.pomderived" value="true"/> <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/> </attributes> </classpathentry> <classpathentry kind="output" path="target/classes"/> </classpath>

这是（2）的.classpath文件的样子：

<?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" output="target/classes" path="src/main/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="src" output="target/test-classes" path="src/test/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER"> <attributes> <attribute name="maven.pomderived" value="true"/> <attribute name="org.eclipse.jst.component.nondependency" value=""/> </attributes> </classpathentry> <classpathentry kind="output" path="target/classes"/> </classpath>

I have two derivatives of the same application, say versions (A) and (B). They each contain projects: (1) test-data-war, which has target/test-classes/log4j.properties, and (2) test-kernel, which has target/test-classes/log4j.properties and target/test-classes/test.properties.

When I run a specific jUnit test in (1), it calls a method in (2) which calls Thread.currentThread().getContextClassLoader().getResourceAsStream(resourceName); In (A), with resourceName as "log4j.properties", the result is not null with a path in (1), but with resourceName as "test.properties" it is null. In (B), with resourceName as "log4j.properties" it is not null with a path in (1) and with resourceName as "test.properties" it is not null with a path in (2).

Why is Thread.currentThread().getContextClassLoader().getResourceAsStream("test.properties"); null in (A)? At first, I thought the classpaths might be different, but they are the same for both (1) and (2).

EDIT: Here is what the .classpath file looks like for (1):

<?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" output="target/classes" path="src/main/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="src" output="target/test-classes" path="src/test/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" pat h="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER"> <attributes> <attribute name="maven.pomderived" value="true"/> <attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/> </attributes> </classpathentry> <classpathentry kind="output" path="target/classes"/> </classpath>

Here is what the .classpath file looks like for (2):

<?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" output="target/classes" path="src/main/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/classes" path="src/main/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="src" output="target/test-classes" path="src/test/java"> <attributes> <attribute name="optional" value="true"/> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry excluding="**" kind="src" output="target/test-classes" path="src/test/resources"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"> <attributes> <attribute name="maven.pomderived" value="true"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER"> <attributes> <attribute name="maven.pomderived" value="true"/> <attribute name="org.eclipse.jst.component.nondependency" value=""/> </attributes> </classpathentry> <classpathentry kind="output" path="target/classes"/> </classpath>

最满意答案

模块test-kernel中的测试类路径的资源对于模块test-data-war是不可见的。 当您将它们作为依赖项添加到另一个模块时，模块仅导出src/main/resources resources下的src/main/resources 。

令人困惑的是Eclipse和Maven在这里不同意。 在Eclipse中，模块的整个类路径是可见的（也是测试资源）。 但是当你在Maven中运行相同的测试时，测试资源会突然消失。 这是因为Eclipse没有“test classpath”的概念。

如果mvn dependency:tree显示差异，那么你需要检查模块的文件pom.xml 。

In (B), there was had an additional dependency in eclipse on (2) that was causing Thread.currentThread().getContextClassLoader().getResourceAsStream("test.properties") to NOT return null. It was actually supposed to return null (i.e. not find test.properties in (2)).