Azkaban的Web Server源码探究系列4: Azkaban Server初始化
上一节做了准备工作，现在开始初始化Azkaban的Web Server.
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第一步就是初始化Velocity的实例
velocityEngine =
configureVelocityEngine(props
.getBoolean(VELOCITY_DEV_MODE_PARAM, false));//
具体的初始化代码如下：
/**
* Creates and configures the velocity engine.
*
* @param devMode
* @return
*/
private VelocityEngine configureVelocityEngine(final boolean devMode) {//
VelocityEngine engine = new VelocityEngine();//org.apache.velocity.app.VelocityEngine
engine.setProperty("resource.loader", "classpath, jar");
engine.setProperty("classpath.resource.loader.class",
ClasspathResourceLoader.class.getName());
engine.setProperty("classpath.resource.loader.cache", !devMode);
engine.setProperty("classpath.resource.loader.modificationCheckInterval",
5L);//
engine.setProperty("jar.resource.loader.class",
JarResourceLoader.class.getName());
engine.setProperty("jar.resource.loader.cache", !devMode);
engine.setProperty("resource.manager.logwhenfound", false);
engine.setProperty("input.encoding", "UTF-8");
engine.setProperty("output.encoding", "UTF-8");
engine.setProperty("directive.set.null.allowed", true);
engine.setProperty("resource.manager.logwhenfound", false);
engine.setProperty("velocimacro.permissions.allow.inline", true);
engine.setProperty("velocimacro.library.autoreload", devMode);
engine.setProperty("velocimacro.library",
"/azkaban/webapp/servlet/velocity/macros.vm");//
engine.setProperty(
"velocimacro.permissions.allow.inline.to.replace.global", true);
engine.setProperty("velocimacro.arguments.strict", true);
engine.setProperty("runtime.log.invalid.references", devMode);
engine.setProperty("runtime.log.logsystem.class", Log4JLogChute.class);
engine.setProperty("runtime.log.logsystem.log4j.logger",
Logger.getLogger("org.apache.velocity.Logger"));
engine.setProperty("parser.pool.size", 3);
return engine;
}
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接下来是初始化SessionCache
/**
* Constructor taking global props.
*
* @param props
*/
public SessionCache(Props props) {//直接调用google的jar包
cache = CacheBuilder.newBuilder()
.maximumSize(props.getInt("max.num.sessions", MAX_NUM_SESSIONS))
.expireAfterAccess(
props.getLong("session.time.to.live", SESSION_TIME_TO_LIVE),
TimeUnit.MILLISECONDS)
.build();//
}
---接下来是创建 XmlUserManager
代码如下：
private UserManager loadUserManager(Props props) {//开始初始化
Class<?> userManagerClass = props.getClass(USER_MANAGER_CLASS_PARAM, null);//"user.manager.class"
logger.info("Loading user manager class " + userManagerClass.getName());
UserManager manager = null;
if (userManagerClass != null
&& userManagerClass.getConstructors().length > 0) {
try {//获取构造函数
Constructor<?> userManagerConstructor =
userManagerClass.getConstructor(Props.class);
manager = (UserManager) userManagerConstructor.newInstance(props);//基于构造函数来生成实例
} catch (Exception e) {
logger.error("Could not instantiate UserManager "
+ userManagerClass.getName());
throw new RuntimeException(e);
}
} else {
manager = new XmlUserManager(props);
}
return manager;
}
构造函数的实例化如下：
public XmlUserManager(Props props) {//看到这里了
xmlPath = props.getString(XML_FILE_PARAM);//"user.manager.xml.file";
parseXMLFile();
}
而parseXMLFile的代码，放到下一节讲解！