为什么 Drools 不能与 Java 8 一起使用？

Question

我刚刚安装了 Java 8 的最终版本。当我尝试使用 Maven 构建我的项目时，如果我使用 Java 8，许多测试都会失败，但使用 Java 7 可以通过。我尝试通过命令行运行它JAVA_HOME 设置为 C:\Program Files\Java\jdk1.8.0 并通过 Eclipse 将 jdk1.8.0 选为已安装 JRE 中的默认 JRE。两者都失败了。请注意，所有失败的测试都使用 Drools 6（及其依赖项）。

这是输出：

-------------------------------------------------------------------------------
Test set: com.local.lds.rules.LocmChiTest
-------------------------------------------------------------------------------
Tests run: 3, Failures: 0, Errors: 3, Skipped: 0, Time elapsed: 1.245 sec <<< FAILURE!
test(com.local.lds.rules.LocmChiTest)  Time elapsed: 0.001 sec  <<< ERROR!
java.lang.ExceptionInInitializerError
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
    at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
    at mockit.Invocation.proceed(Invocation.java:192)
    at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
    at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
    at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
    at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
    at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
    at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
    at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
    at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)
Caused by: java.lang.RuntimeException: wrong class format
    at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:279)
    at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:219)
    at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.askForType(LookupEnvironment.java:113)
    at org.eclipse.jdt.internal.compiler.lookup.UnresolvedReferenceBinding.resolve(UnresolvedReferenceBinding.java:49)
    at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveType(BinaryTypeBinding.java:122)
    at org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding.resolve(ParameterizedTypeBinding.java:861)
    at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveType(BinaryTypeBinding.java:100)
    at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveTypeFor(BinaryTypeBinding.java:1081)
    at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.getField(BinaryTypeBinding.java:869)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.findField(Scope.java:1052)
    at org.eclipse.jdt.internal.compiler.lookup.Scope.findField(Scope.java:998)
    at org.eclipse.jdt.internal.compiler.lookup.MethodScope.findField(MethodScope.java:354)
    at org.eclipse.jdt.internal.compiler.lookup.BlockScope.getBinding(BlockScope.java:474)
    at org.eclipse.jdt.internal.compiler.ast.QualifiedNameReference.resolveType(QualifiedNameReference.java:930)
    at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:374)
    at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:947)
    at org.eclipse.jdt.internal.compiler.ast.Block.resolve(Block.java:90)
    at org.eclipse.jdt.internal.compiler.ast.IfStatement.resolve(IfStatement.java:260)
    at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolveStatements(AbstractMethodDeclaration.java:456)
    at org.eclipse.jdt.internal.compiler.ast.MethodDeclaration.resolveStatements(MethodDeclaration.java:252)
    at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:415)
    at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1148)
    at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1258)
    at org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration.resolve(CompilationUnitDeclaration.java:539)
    at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:763)
    at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:468)
    at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:405)
    at org.drools.compiler.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:49)
    at org.drools.compiler.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:405)
    at org.drools.compiler.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:46)
    at org.drools.compiler.compiler.PackageRegistry.compileAll(PackageRegistry.java:110)
    at org.drools.compiler.compiler.PackageBuilder.compileAll(PackageBuilder.java:1334)
    at org.drools.compiler.compiler.PackageBuilder.compileAllRules(PackageBuilder.java:975)
    at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildRules(CompositeKnowledgeBuilderImpl.java:266)
    at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:98)
    at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:87)
    at org.drools.compiler.kie.builder.impl.AbstractKieModule.buildKnowledgePackages(AbstractKieModule.java:204)
    at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:39)
    at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:323)
    at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:193)
    at com.local.lds.rules.RuleEngineManager.buildKieBase(RuleEngineManager.java:90)
    at com.local.lds.rules.LocmChiTest.<clinit>(LocmChiTest.java:33)
    ... 41 more
Caused by: org.eclipse.jdt.internal.compiler.classfmt.ClassFormatException
    at org.eclipse.jdt.internal.compiler.classfmt.ClassFileReader.<init>(ClassFileReader.java:372)
    at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.createNameEnvironmentAnswer(EclipseJavaCompiler.java:303)
    at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:274)
    ... 82 more
testNoFeatured(com.local.lds.rules.LocmChiTest)  Time elapsed: 0 sec  <<< ERROR!
java.lang.NoClassDefFoundError: Could not initialize class com.local.lds.rules.LocmChiTest
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
    at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
    at mockit.Invocation.proceed(Invocation.java:192)
    at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
    at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
    at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
    at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
    at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
    at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
    at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
    at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)
testFeaturedSort(com.local.lds.rules.LocmChiTest)  Time elapsed: 0.001 sec  <<< ERROR!
java.lang.NoClassDefFoundError: Could not initialize class com.local.lds.rules.LocmChiTest
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
    at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
    at mockit.Invocation.proceed(Invocation.java:192)
    at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
    at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
    at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
    at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
    at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
    at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
    at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
    at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
    at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)

那么这是 Java 8、Maven、Surefire 插件还是 Drools 的问题？

Answer 1

将 org.eclipse.jdt.core.jar 更新为最新可用的。

在我们的例子中，我们已将 org.eclipse.jdt.core-3.5.1.v_972_R35x.jar 更新为 org.eclipse.jdt.core_3.11.2.v20160128-0629.jar。

这是决定编译drools代码的java_version的jar。

一旦你的旧的 java-6 兼容的 drools 代码在 java -8 中编译。您可以使用 java -8 运行它而不会出现任何此类错误。 这些都是经过验证的步骤。 如有任何疑问，请回复。

Answer 2

我已经通过在 maven 中编辑 pom 解决了这个问题。

    <dependency>
        <groupId>org.eclipse.jdt.core.compiler</groupId>
        <artifactId>ecj</artifactId>
        <version>4.5.1</version>
    </dependency>

    <!-- core -->
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-core</artifactId>
        <version>5.5.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.drools</groupId>
        <artifactId>drools-compiler</artifactId>
        <version>5.5.0.Final</version>
        <exclusions>
            <exclusion>
                <groupId>org.eclipse.jdt.core.compiler</groupId>
                <artifactId>ecj</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

Answer 3

ECJ 用于在您的规则中编译 java 代码，最近才开始支持 Java 8 语法和 Luna (4.4)，因此需要更新。

如果您想在规则中使用 Java 8 语法，您还需要使用 Drools 6.4.0.Final，因为他们现在将 Java 8 识别为 Java 8（他们将 8 映射到 7 以解决 ECJ 4.3 的问题)

MVEL 2.2.X 版本或更高版本，它是 Java 语法的简写替代方案，也支持 Java 8。

Answer 4

将您的 org.eclipse.jdt.internal.compiler(ecj.jar) 更新到最新版本，即使用 ecj-4.4.jar 并尝试。

Answer 5

看起来像 Drools 中的错误（在默认的 Eclipse 编译器中）：

• Bugzilla
• JIRA（感谢劳恩）

他们正在考虑在6.1.0.Beta2 中修复它。

同时，试试这个解决方法： 将ecj 依赖覆盖到版本4.3.1。