tomcat common.loader&server.loader&shared.loader

samsungsamsung

　　${catalina.home}/conf/catalina.properties文件可以用来配置tomcat内置classloader的load范围，一般默认情况如下


# List of comma-separated paths defining the contents of the "common"

# classloader. Prefixes should be used to define what is the repository type.

# Path may be relative to the CATALINA_HOME or CATALINA_BASE path or absolute.

# If left as blank,the JVM system loader will be used as Catalina's "common"

# loader.

# Examples:

#     "foo": Add this folder as a class repository

#     "foo/*.jar": Add all the JARs of the specified folder as class

#                  repositories

#     "foo/bar.jar": Add bar.jar as a class repository

common.loader=${catalina.base}/lib,${catalina.base}/lib/*.jar,${catalina.home}/lib,${catalina.home}/lib/*.jar


#

# List of comma-separated paths defining the contents of the "server"

# classloader. Prefixes should be used to define what is the repository type.

# Path may be relative to the CATALINA_HOME or CATALINA_BASE path or absolute.

# If left as blank, the "common" loader will be used as Catalina's "server"

# loader.

# Examples:

#     "foo": Add this folder as a class repository

#     "foo/*.jar": Add all the JARs of the specified folder as class

#                  repositories

#     "foo/bar.jar": Add bar.jar as a class repository

server.loader=


#

# List of comma-separated paths defining the contents of the "shared"

# classloader. Prefixes should be used to define what is the repository type.

# Path may be relative to the CATALINA_BASE path or absolute. If left as blank,

# the "common" loader will be used as Catalina's "shared" loader.

# Examples:

#     "foo": Add this folder as a class repository

#     "foo/*.jar": Add all the JARs of the specified folder as class

#                  repositories

#     "foo/bar.jar": Add bar.jar as a class repository

# Please note that for single jars, e.g. bar.jar, you need the URL form

# starting with file:.

shared.loader=


下面两个方法都是copy自/Tomcat 6.0/java/org/apache/catalina/startup/Bootstrap.java，tomcat的启动类


    //下面三个classloader创建好，上面配置文件指定了load path，注意classpath下面并没有tomcat的自身类，所以 
　　//appclassloader是加载不到的

 


    private void initClassLoaders() {
try {
commonLoader = createClassLoader("common", null);
if( commonLoader == null ) {
// no config file, default to this loader - we might be in a 'single' env.
commonLoader=this.getClass().getClassLoader();
}
catalinaLoader = createClassLoader("server", commonLoader);
sharedLoader = createClassLoader("shared", commonLoader);
} catch (Throwable t) {
log.error("Class loader creation threw exception", t);
System.exit(1);
}
}
 　　


public void init()
throws Exception
{
// Set Catalina path
setCatalinaHome();
setCatalinaBase();
initClassLoaders();
Thread.currentThread().setContextClassLoader(catalinaLoader);
//tomcat的启动类是在classpath下面的，由appclassloader加载，然后接下来的各个tomcat自身类由catalinaLoader加载，由于classloader的传递特性
//due to the classloader here, so the later classloader will be catalinaLoader
Class startupClass =
catalinaLoader.loadClass
("org.apache.catalina.startup.Catalina");
Object startupInstance = startupClass.newInstance();
Method method =
startupInstance.getClass().getMethod(methodName, paramTypes);
method.invoke(startupInstance, paramValues);
catalinaDaemon = startupInstance;
}