1.问题
今天在本地和测试环境用jetty跑应用发现本地环境跑起来有问题，而测试环境却没有问题，出现的是war包的WEB-INF的lib目录下有两个jar包a.jar和b.jar，但是这两个jar包邮两个包名和类目一样，但是功能却不一样的类，那么jetty启动加载这个类的时候用的是a.jar里面的类还是b.jar里面的类呢，出了问题只能查了。
2.本地环境jetty加载目录里面是b.jar排在a.jar前面，而测试环境是a.jar排在b.jar前面，而记载a.jar里面的类是正确的。我们看看jetty怎么处理：
首先jetty加载一个APP war的过程中WebInfConfiguration.java类里面加载类的顺序，优先加载的是WEB-INF/classes，然后再加载WEB-INF/lib里面的jar包，而jar的加载顺序又是怎么样的呢？
@Override
public void configure(WebAppContext context) throws Exception
{
//cannot configure if the context is already started
if (context.isStarted())
{
if (Log.isDebugEnabled()){Log.debug("Cannot configure webapp "+context+" after it is started");}
return;
}
Resource web_inf = context.getWebInf();
// Add WEB-INF classes and lib classpaths
if (web_inf != null && web_inf.isDirectory() && context.getClassLoader() instanceof WebAppClassLoader)
{
// Look for classes directory
Resource classes= web_inf.addPath("classes/");
if (classes.exists())
((WebAppClassLoader)context.getClassLoader()).addClassPath(classes);
// Look for jars
Resource lib= web_inf.addPath("lib/");
if (lib.exists() || lib.isDirectory())
((WebAppClassLoader)context.getClassLoader()).addJars(lib);
}
// Look for extra resource
List<Resource> resources = (List<Resource>)context.getAttribute(RESOURCE_URLS);
if (resources!=null)
{
Resource[] collection=new Resource[resources.size()+1];
int i=0;
collection[i++]=context.getBaseResource();
for (Resource resource : resources)
collection[i++]=resource;
context.setBaseResource(new ResourceCollection(collection));
}
}
((WebAppClassLoader)context.getClassLoader()).addClassPath(classes); 这是加载每个class类的过程
addURL(url);调用jdk包的URLClassPath把每个class文件放到list的后续，每次加载类的时候从这个list第一个开始查找，找到则加载
这里看完我们就可以再看加载lib下面的jar包的过程了
addJars是对lib下面所有jar包用jdk的list方法获取所有jar包，然后对每个jar进行处理。
/* ------------------------------------------------------------ */
/** Add elements to the class path for the context from the jar and zip files found
* in the specified resource.
* @param lib the resource that contains the jar and/or zip files.
*/
public void addJars(Resource lib)
{
if (lib.exists() && lib.isDirectory())
{
String[] files=lib.list();
for (int f=0;files!=null && f<files.length;f++)
{
try
{
Resource fn=lib.addPath(files[f]);
String fnlc=fn.getName().toLowerCase();
if (!fn.isDirectory() && isFileSupported(fnlc))
{
String jar=fn.toString();
jar=StringUtil.replace(jar, ",", "%2C");
jar=StringUtil.replace(jar, ";", "%3B");
addClassPath(jar);
}
}
catch (Exception ex)
{
Log.warn(Log.EXCEPTION,ex);
}
}
}
}
String[] files=lib.list(); 这一行就是关系jar包的加载顺序关键点，这里列出来的顺序就是jar包的加载顺序，
/* --------------------------------------------------------- */
/**
* Returns a list of resources contained in the given resource
*/
@Override
public String[] list()
{
String[] list =_file.list();
if (list==null)
return null;
for (int i=list.length;i-->0;)
{
if (new File(_file,list[i]).isDirectory() &&
!list[i].endsWith("/"))
list[i]+="/";
}
return list;
}
最终 String[] list =_file.list();就是java.io.File的list方法，而这个方法的顺序是怎么样，只能看jdk的代码了。我们写个程序简单测试下
import java.io.File;
public class FileListTest {
/**
* @param args
*/
public static void main(String[] args) {
String[] files = new File("E:\\project\\20120801_161305_1_industry\\bundle\\war\\target\\industry.bundle.war-1.0-SNAPSHOT\\WEB-INF\\lib").list();
for(String str: files){
System.out.println(str);
}
}
}
ajax.jsonlib-2.2.jar ajax.json__ezmorph-1.0.4.jar-2.2.jar ajax.json__json-lib-2.2-jdk15.jar-2.2.jar apache.activemq-5.3.0-patch.jar apache.geronimo.j2ee-management-1.0.1.jar apache.geronimo.jms-1.1.1.jar apache.hadoop.zookeeper-3.3.3.jar authz.core-1.0.0-20120801.064744-6.jar authz.member-1.0.0-20120802.004050-7.jar authz.webx3-1.0.0-20120718.012318-8.jar base.common-1.0.9.6.jar base.dal-1.0.9.6.jar base.privilege-1.0.9.6.jar base.resource-1.0.9.6.jar bouncycastle.provider-1.38-jdk15.jar brand_shared.api-1.0-SNAPSHOT.jar buc.sso.client-0.1.9.jar buc.sso.common-0.1.9.jar cat.client-2.0.0.jar caucho.hessian-3.2.0.jar cmshollywood.dispatcher-1.0.0-20111227.062653-5.jar codehaus.groovy-1.6.3.jar codehaus.jackson.core-1.5.4.jar codehaus.jackson.mapper-1.5.4.jar codehaus.mvel-2.0.6.jar concurrent-0.0.0.jar dragoon-common-2.7.0.jar druid-0.2.1.jar dubbo-1.0.99-dummy.jar dubbo.all-2.0-20120731.012520-32.jar dubbo.core.api-1.0.99-dummy.jar dubbo.core.common-1.0.99-dummy.jar dubbo.core.registry.default-1.0.99-dummy.jar dubbo.core.rpc-1.0.99-dummy.jar dubbo.core.rpc.dbo-1.0.99-dummy.jar dubbo.core.rpc.http-1.0.99-dummy.jar dubbo.core.service-1.0.99-dummy.jar dubbo.core.service.server-1.0.99-dummy.jar dubbo.hessian.lite-3.2.1.osgi_03.jar dubbo.remoting-2.3.7.jar dubbo.rpc-2.3.7.jar eclipse.aspectj-1.5.4.jar eclipse.aspectj.weaver-1.6.5.jar fastjson-1.1.9.jar fasttext-css-1.3.22.jar fasttext-html-1.3.5.jar fasttext-psoriasis-1.3.22.jar fasttext-sec-1.3.22.jar fasttext-segment-1.3.22.jar fasttext-utils-1.3.22.jar fasttext.all-1.3-20120502.125625-30.jar gene_shared.api-1.0-20120724.041644-61.jar gene_shared.biz.common-1.0-20120724.041541-64.jar headquarters.biz.cache-1.3-20120614.020233-9544.jar headquarters.biz.common-1.1-20110426.054945-9.jar headquarters.biz.viewcache-1.2-20120711.041231-16.jar headquarters.biz.viewcachebase-1.2-20120711.041154-19.jar headquarters.capsule-2.5-20120711.041905-10.jar headquarters.commons.fasttext-1.2-20120614.020242-10138.jar headquarters.jdbc.proxy-1.1-20120711.041307-7.jar industry.biz.apiimp-1.0-SNAPSHOT.jar industry.biz.brand-1.0-SNAPSHOT.jar industry.common.config-1.0-SNAPSHOT.jar industry.dal-1.0-SNAPSHOT.jar industry.web.brand-1.0-SNAPSHOT.jar industry.web.brandbops-1.0-SNAPSHOT.jar jakarta.ant-1.7.1.jar jakarta.ant.launcher-1.7.1.jar jakarta.commons.beanutils-1.7.0.jar jakarta.commons.codec-1.3.jar jakarta.commons.collections-3.2.1.jar jakarta.commons.configuration-1.5a.jar jakarta.commons.dbcp-1.4.jar jakarta.commons.digester-1.8.jar jakarta.commons.fileupload-1.2.1.jar jakarta.commons.httpclient-3.1.jar jakarta.commons.io-1.4.jar jakarta.commons.jelly-1.0-RC1.jar jakarta.commons.jexl-1.1.jar jakarta.commons.lang-2.4.jar jakarta.commons.logging-1.1.jar jakarta.commons.pool-1.5.4.jar jakarta.ecs-1.4.2.jar jakarta.log4j-1.2.16.jar jakarta.oro-0.0.0.jar jakarta.taglib.jstl-0.0.0.jar jakarta.taglib.jstl.support-0.0.0.jar jakarta.velocity-1.6.4.jar java.jce.cryptix-0.0.0.jar jboss.hornetq-core-client-2.2.13.jar jboss.jboss-netty-3.2.5.Final.jar jdbc.mysql.mysql-connector-5.0.4.jar jdbc.oracle-11.1.0.7.jar libra_shared.biz-1.0-20120503.051641-5.jar libra_shared.dal-1.0-20120315.051425-2.jar libra_shared.service-1.0-20120315.051506-2.jar member.service.api-1.0.0-20120801.064645-19.jar member.service.model-1.0.0-20120801.064625-22.jar misc.aspectj__aspectjrt-1.6.5.jar-1.6.5.jar misc.aspectj__aspectjweaver-1.6.5.jar-1.6.5.jar misc.htmlparser-0.0.0.jar misc.javassist-3.9.0.GA.jar misc.javasvn-1.3.0.jar misc.javasvn__jna.jar-1.3.0.jar misc.javasvn__svnkit-1.3.0.jar-1.3.0.jar misc.javasvn__svnkit-cli-1.3.0.jar-1.3.0.jar misc.javasvn__svnkit-javahl-1.3.0.jar-1.3.0.jar misc.javasvn__trilead.jar-1.3.0.jar misc.jgroup-2.4.1.1.jar napoli.client-1.5.6.jar napoli.common-1.5.6.jar napoli.dragoon-1.5.6.jar napoli.normandy-1.5.6.jar network.core-1.2.9.jar nonda.core-0.1.2.jar nonda.databind-0.1.2.jar nonda.databind-webx3-0.1.2.jar nonda.validation-0.1.2.jar nonda.validation-webx3-0.1.2.jar normandy.client-1.0.0.jar normandy.common-1.0.0.jar objectweb.asm-0.0.0.jar objectweb.asm.attrs-0.0.0.jar offer.api.commons-1.0.0-20120801.063531-24.jar offer.api.core-1.0.0-20120801.063619-53.jar offer.api.query-1.0.0-20120717.042556-53.jar offer.enums-1.0.0-20120717.042329-48.jar offer.shared.codes-1.0.0-20120717.042349-38.jar opensymphony.oscache-0.0.0.jar opensymphony.quartz-1.6.1.jar oracle.berkeleydb-3.2.76-patch.jar org.slf4j.jcl-over-slf4j-1.5.6.jar org.slf4j.jcl104-over-slf4j-1.5.6.jar org.slf4j.slf4j-api-1.5.6.jar org.slf4j.slf4j-log4j12-1.5.2.jar pc2.client.agent-1.2.5.jar pc2.common-1.2.5.jar pivot.dal.offer-1.2-20120730.110022-70.jar searchad.searchengine-2.5-20120717.060401-38.jar server.jetty.jetty-core-6.1.21.jar server.jetty.jetty-util-6.1.21.jar sourceforge.c3p0-0.9.1.jar sourceforge.c3p0.oracle-0.9.1.jar sourceforge.cglib-nodep-2.1_3.jar sourceforge.freemarker-2.3.15.jar sourceforge.ibatis-2.3.0.jar sourceforge.jaxen-1.1.jar sourceforge.jline-0.9.94.jar sourceforge.pinyin4j-2.5.0.jar sourceforge.saxpath-1.0.jar sourceforge.spring-2.5.6.jar sourceforge.spring.modules.beans-2.5.6.SEC02.jar sourceforge.spring.modules.core-2.5.6.SEC02.jar sourceforge.spring.modules.webmvc-2.5.6.SEC02.jar sourceforge.spring.weaving.aspects-2.5.4.jar tagclient-1.0.0-20120712.041856-2.jar tagcommon-1.0.0-20120712.041809-2.jar test.junit-3.8.1.jar test.objenesis-1.0.jar toolkit.biz.command-1.0.jar toolkit.common.collection-1.0.jar toolkit.common.configuration-1.0.jar toolkit.common.convert-1.0.jar toolkit.common.expression-1.0.jar toolkit.common.lang-1.0.jar toolkit.common.logging-1.0.jar toolkit.common.regexp-1.0.jar toolkit.common.resourcebundle-1.0.jar toolkit.sandbox.shy2-0.1.jar toolkit.service.form-1.0.jar toolkit.service.framework-1.0.jar toolkit.service.freemarker-1.0.jar toolkit.service.jsp-1.0.jar toolkit.service.localization-1.0.jar toolkit.service.mail-1.0.jar toolkit.service.mimetype-1.0.jar toolkit.service.naming-1.0.jar toolkit.service.pipeline-1.0.jar toolkit.service.pool-1.0.jar toolkit.service.pull-1.0.jar toolkit.service.resource-1.0.jar toolkit.service.rundata-1.0.jar toolkit.service.spring-1.0.jar toolkit.service.template-1.0.jar toolkit.service.threadcontext-1.0.jar toolkit.service.upload-1.0.jar toolkit.service.uribroker-1.0.jar toolkit.service.velocity-1.0.jar toolkit.webx.framework-2.0.jar toolkit.webx.request-2.0.jar toolkit.webx.turbine-2.0.jar toolkit.webx.turbine.tld-2.0.jar webx2-2.0.1.jar webx3.compat-3.0.6.jar webx3.core-3.0.6.jar webx3.extension.migration.china-1.0-20120627.081453-1.jar webx3.extension.rpc-0.2.6.jar whalin.memcached-0.0.0.jar work_shared.common-1.0-20120528.090917-5.jar work_shared.dal-1.0-20120531.040958-10.jar work_shared.service-1.0-20120528.091004-9.jar xml.apis-1.0.b2.jar xml.apis.css-1.3.jar xml.commons-resolver-0.0.0.jar xml.dom4j-1.6.1.jar xml.jox-0.0.0.jar xml.jox__dtdparser-1.13.jar-0.0.0.jar xml.jox__jox-1.16.jar-0.0.0.jar xml.nekohtml-1.9.9.jar xml.xerces-0.0.0.jar xml.xmlgraphics-1.7.jar xml.xmlgraphics__batik-css-1.7.jar-1.7.jar xml.xmlgraphics__batik-util-1.6-1.jar-1.7.jar xml.xpp3-1.1.4c.jar xml.xstream-1.3.1.jar zk.zkclient-0.1.0.jar
从这里看出来就是jar包名称的字母序的顺序。
从jar里面解析出class类看下：JarFileResource
/* ------------------------------------------------------------ */
@Override
public synchronized String[] list()
{
if(isDirectory() && _list==null)
{
ArrayList list = new ArrayList(32);
checkConnection();
JarFile jarFile=_jarFile;
if(jarFile==null)
{
try
{
JarURLConnection jc=(JarURLConnection)((new URL(_jarUrl)).openConnection());
jc.setUseCaches(getUseCaches());
jarFile=jc.getJarFile();
}
catch(Exception e)
{
Log.ignore(e);
}
}
Enumeration e=jarFile.entries();
String dir=_urlString.substring(_urlString.indexOf("!/")+2);
while(e.hasMoreElements())
{
JarEntry entry = (JarEntry) e.nextElement();
String name=entry.getName().replace('\\','/');
if(!name.startsWith(dir) || name.length()==dir.length())
{
continue;
}
String listName=name.substring(dir.length());
int dash=listName.indexOf('/');
if (dash>=0)
{
//when listing jar:file urls, you get back one
//entry for the dir itself, which we ignore
if (dash==0 && listName.length()==1)
continue;
//when listing jar:file urls, all files and
//subdirs have a leading /, which we remove
if (dash==0)
listName=listName.substring(dash+1, listName.length());
else
listName=listName.substring(0,dash+1);
if (list.contains(listName))
continue;
}
list.add(listName);
}
_list=new String[list.size()];
list.toArray(_list);
}
return _list;
}
作者：zhongweijian 发表于2013-1-28 22:54:23 原文链接
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