slf4j jar包冲突和spring的bean解析异常

由于种种原因，项目的结构被调整成了ant+maven共同管控的样子（真的好挫）

于是，一个最基本的问题来了，之前写的UT没法跑了。

首先爆出来的是slf4j的问题：

 

SLF4J: See http://www.slf4j.org/codes.html#version_mismatch for further details. 
Exception in thread "main" java.lang.NoSuchMethodError: org.slf4j.spi.LocationAwareLogger.log(Lorg/slf4j/Marker;Ljava/lang/String;ILjava/lang/String;[Ljava/lang/Object;Ljava/lang/Throwable;)V 
at org.apache.commons.logging.impl.SLF4JLocationAwareLog.info(SLF4JLocationAwareLog.java:159) 
at org.springframework.context.support.AbstractApplicationContext.prepareRefresh(AbstractApplicationContext.java:456)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:394) 
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:140) 
at org.springframework.context.support.FileSystemXmlApplicationContext.<init>(FileSystemXmlApplicationContext.java:94) 
at main.Run.main(Run.java:33) 

到依赖的classpath里面一find，发现下面至少有1.4.3、1.5.10、1.5.6、1.6.1几个版本的slf4j的jar包共存。。。

处理方案：

全部干掉，仅保留一套最slf4j组件，即：留个接口包： slf4j-api，留个实现包：slf4j-log4j12。

 

一位搞定这个问题了，结果spring的bean解析又出问题了。。。

 

Caused by: java.lang.NoSuchFieldError: fRecognizedFeatures
	at org.apache.xerces.parsers.BasicParserConfiguration.<init>(Unknown Source)
	at org.apache.xerces.parsers.DTDConfiguration.<init>(Unknown Source)
	at org.apache.xerces.parsers.StandardParserConfiguration.<init>(Unknown Source)
	at org.apache.xerces.parsers.IntegratedParserConfiguration.<init>(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.<init>(Unknown Source)
	at org.apache.xerces.parsers.XML11Configuration.<init>(Unknown Source)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at java.lang.Class.newInstance0(Class.java:355)
	at java.lang.Class.newInstance(Class.java:308)
	at org.apache.xerces.util.ObjectFactory.newInstance(Unknown Source)
	at org.apache.xerces.util.ObjectFactory.findJarServiceProvider(Unknown Source)
	at org.apache.xerces.util.ObjectFactory.createObject(Unknown Source)
	at org.apache.xerces.util.ObjectFactory.createObject(Unknown Source)
	at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
	at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
	at org.apache.xerces.jaxp.DocumentBuilderImpl.<init>(Unknown Source)
	at org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.setAttribute(Unknown Source)
	at org.springframework.beans.factory.xml.DefaultDocumentLoader.createDocumentBuilderFactory(DefaultDocumentLoader.java:99)
	at org.springframework.beans.factory.xml.DefaultDocumentLoader.loadDocument(DefaultDocumentLoader.java:70)
	at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:396)
	... 34 more

这次又是因为xml.xerces.jar和jdk自带的xml解析工具类冲突导致的，又是jar包冲突！！！

这个问题的解决方案有好几个，可以参考：这里

1、Use the “javax.xml.parsers.DocumentBuilderFactory” system property.

2、Use the properties file "lib/jaxp.properties" in the JRE directory.

3、Use the Services API (as detailed in the JAR specification), if available, to determine the classname. The Services API will look for a classname in the file “META-INF/services/javax.xml.parsers.DocumentBuilderFactory"  in jars available to the runtime.

4、Platform default "DocumentBuilderFactory" instance，也就是类com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl。

我采用了一种简单的方式，在jvm的启动参数中加上下面的参数明确制定要用哪个实现类。

 

-Djavax.xml.parsers.DocumentBuilderFactory=com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderFactoryImpl
-Djavax.xml.parsers.SAXParserFactory=com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl