【原创】大叔经验分享（16）Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher

今天尝试运行一个古老的工程，配置好之后编译通过，结果运行时报错：

org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from class path resource [applicationContext.xml]; nested exception is java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher

at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:420)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:212)
at org.springframework.test.AbstractSingleSpringContextTests.createApplicationContext(AbstractSingleSpringContextTests.java:212)
at org.springframework.test.AbstractSingleSpringContextTests.loadContextLocations(AbstractSingleSpringContextTests.java:189)
at org.springframework.test.AbstractSingleSpringContextTests.loadContext(AbstractSingleSpringContextTests.java:169)
at org.springframework.test.AbstractSpringContextTests.getContext(AbstractSpringContextTests.java:140)
at org.springframework.test.AbstractSingleSpringContextTests.setUp(AbstractSingleSpringContextTests.java:98)
at junit.framework.TestCase.runBare(TestCase.java:125)
at org.springframework.test.ConditionalTestCase.runBare(ConditionalTestCase.java:76)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at junit.textui.TestRunner.doRun(TestRunner.java:116)
at com.intellij.junit3.JUnit3IdeaTestRunner.doRun(JUnit3IdeaTestRunner.java:113)
at junit.textui.TestRunner.doRun(TestRunner.java:109)
at com.intellij.junit3.JUnit3IdeaTestRunner.startRunnerWithArgs(JUnit3IdeaTestRunner.java:45)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher
at org.springframework.context.config.ContextNamespaceHandler$1.parse(ContextNamespaceHandler.java:65)
at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:69)
at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1297)
at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1287)
at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:135)
at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:92)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:507)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:398)
... 24 more

我用的jdk1.8，为什么一直报这个错，百思不得其解，其中spring的jar也看不到版本号，好吧，直接反编译看看

org.springframework.context.config.ContextNamespaceHandler

    private void registerJava5DependentParser(final String elementName, final String parserClassName) {
        BeanDefinitionParser parser = null;
        if(JdkVersion.isAtLeastJava15()) {
            try {
                Class parserClass = ClassUtils.forName(parserClassName, ContextNamespaceHandler.class.getClassLoader());
                parser = (BeanDefinitionParser)parserClass.newInstance();
            } catch (Throwable var5) {
                throw new IllegalStateException("Unable to create Java 1.5 dependent parser: " + parserClassName, var5);
            }
        } else {
            parser = new BeanDefinitionParser() {
                public BeanDefinition parse(Element element, ParserContext parserContext) {
                    throw new IllegalStateException("Context namespace element '" + elementName + "' and its parser class [" + parserClassName + "] are only available on JDK 1.5 and higher");
                }
            };
        }

        this.registerBeanDefinitionParser(elementName, parser);
    }

org.springframework.core.JdkVersion

    public static boolean isAtLeastJava15() {
        return getMajorJavaVersion() >= 2;
    }

    public static boolean isAtLeastJava16() {
        return getMajorJavaVersion() >= 3;
    }

    static {
        if(javaVersion.indexOf("1.7.") != -1) {
            majorJavaVersion = 4;
        } else if(javaVersion.indexOf("1.6.") != -1) {
            majorJavaVersion = 3;
        } else if(javaVersion.indexOf("1.5.") != -1) {
            majorJavaVersion = 2;
        } else {
            majorJavaVersion = 1;
        }

    }

好吧，硬编码只支持1.5、1.6和1.7，不服不行，只能降jdk到1.7再运行。