servlet解析演进（7）-session（1）
session是web项目中重要的概念。servlet请求通过session、request等对象保存不同生命周期的数据。
1、session类
servlet解析过程中会涉及到以下几类session信息
StandardSessionFacede被包含在StandardSession中，作为对外暴漏的门面，既能够为servlet展示需要的方法，又屏蔽了一些StandardSession中一些不想暴库的方法。
//session接口的标准实现。这个对象实现了serializable接口，所以他能够在不同的jvm中存储和传输
//session信息，实现了对分布式session的支持
//类实例代表着内部级别和应用级别的session展示。然而因为这个类本身没有被生命为public，
// 所以org.apache.catalina.session 包外的java逻辑不能讲httpSession实例返回给Session
//如果你为这个类增加属性，你必须确保这个属性覆盖了read/writeObject 方法，以便这个类能够被
//正确的序列化。
class StandardSession
implements HttpSession, Session, Serializable {
//session关联的管理器manager
public StandardSession(Manager manager) {
super();
this.manager = manager;
if (manager instanceof ManagerBase)
this.debug = ((ManagerBase) manager).getDebug();
}
//无法序列化时抛出的错误信息
private static final String NOT_SERIALIZED =
"___NOT_SERIALIZABLE_EXCEPTION___";
//属性容器
private HashMap attributes = new HashMap();
//认证类型
private transient String authType = null;
/**
* The <code>java.lang.Method</code> for the
* <code>fireContainerEvent()</code> method of the
* <code>org.apache.catalina.core.StandardContext</code> method,
* if our Context implementation is of this class. This value is
* computed dynamically the first time it is needed, or after
* a session reload (since it is declared transient).
*/
private transient Method containerEventMethod = null;
/**
* The method signature for the <code>fireContainerEvent</code> method.
*/
private static final Class containerEventTypes[] =
{ String.class, Object.class };
//session创建时间
private long creationTime = 0L;
//debug级别
private transient int debug = 0;
//过期时间
private transient boolean expiring = false;
//该类的门面实例
private transient StandardSessionFacade facade = null;
//唯一标示
private String id = null;
//类描述信息
private static final String info = "StandardSession/1.0";
//最后一次访问时间，初始化为创建时间
private long lastAccessedTime = creationTime;
//session的监听器链表
private transient ArrayList listeners = new ArrayList();
//session管理器
private Manager manager = null;
//session访问的最大间隔时间，如果超过该时间会该session会置为过期。如果是负数，则表示session永不过期
private int maxInactiveInterval = -1;
//标示session是新旧
private boolean isNew = false;
//session是否有效
private boolean isValid = false;
//关联该session的内部注释
private transient HashMap notes = new HashMap();
//关联该session的授权原则
private transient Principal principal = null;
//包描述信息
private static StringManager sm =
StringManager.getManager(Constants.Package);
//session关联的http session上下文
private static HttpSessionContext sessionContext = null;
//该容器的属性变更（不能序列化）
/**
* The property change support for this component. NOTE: This value
* is not included in the serialized version of this object.
*/
private transient PropertyChangeSupport support =
new PropertyChangeSupport(this);
//当前访问时间
private long thisAccessedTime = creationTime;
public String getAuthType() {
return (this.authType);
}
public void setAuthType(String authType) {
String oldAuthType = this.authType;
this.authType = authType;
//如果authType属性有变化会触发属性变更监听
support.firePropertyChange("authType", oldAuthType, this.authType);
}
//设置当前时间为创建时间、最后访问时间、当前访问时间
public void setCreationTime(long time) {
this.creationTime = time;
this.lastAccessedTime = time;
this.thisAccessedTime = time;
}
public String getId() {
return (this.id);
}
public void setId(String id) {
if ((this.id != null) && (manager != null))
manager.remove(this);
//设置id
this.id = id;
//管理器管理当前类的门面类。
if (manager != null)
manager.add(this);
//触发session监听事件
// Notify interested session event listeners
fireSessionEvent(Session.SESSION_CREATED_EVENT, null);
// 获取容器上下文。
Context context = (Context) manager.getContainer();
//监听器数组
Object listeners[] = context.getApplicationListeners();
if (listeners != null) {
HttpSessionEvent event =
new HttpSessionEvent(getSession());
for (int i = 0; i < listeners.length; i++) {
if (!(listeners[i] instanceof HttpSessionListener))
continue;
HttpSessionListener listener =
(HttpSessionListener) listeners[i];
try {
fireContainerEvent(context,
"beforeSessionCreated",
listener);
//创建session事件
listener.sessionCreated(event);
fireContainerEvent(context,
"afterSessionCreated",
listener);
} catch (Throwable t) {
try {
fireContainerEvent(context,
"afterSessionCreated",
listener);
} catch (Exception e) {
;
}
// FIXME - should we do anything besides log these?
log(sm.getString("standardSession.sessionEvent"), t);
}
}
}
}
public String getInfo() {
return (this.info);
}
public long getLastAccessedTime() {
return (this.lastAccessedTime);
}
public Manager getManager() {
return (this.manager);
}
public void setManager(Manager manager) {
this.manager = manager;
}
public int getMaxInactiveInterval() {
return (this.maxInactiveInterval);
}
public void setMaxInactiveInterval(int interval) {
this.maxInactiveInterval = interval;
}
public void setNew(boolean isNew) {
this.isNew = isNew;
}
public Principal getPrincipal() {
return (this.principal);
}
public void setPrincipal(Principal principal) {
Principal oldPrincipal = this.principal;
this.principal = principal;
support.firePropertyChange("principal", oldPrincipal, this.principal);
}
//返回该类的session门面
public HttpSession getSession() {
if (facade == null)
facade = new StandardSessionFacade(this);
return (facade);
}
//是否合法
public boolean isValid() {
return (this.isValid);
}
public void setValid(boolean isValid) {
this.isValid = isValid;
}
//访问
public void access() {
this.isNew = false;
this.lastAccessedTime = this.thisAccessedTime;
this.thisAccessedTime = System.currentTimeMillis();
}
//添加监听器
public void addSessionListener(SessionListener listener) {
synchronized (listeners) {
listeners.add(listener);
}
}
//是否过期
public void expire() {
expire(true);
}
//过期session实例
public void expire(boolean notify) {
// Mark this session as "being expired" if needed
if (expiring)
return;
//标示是否正在做过期动作，如果正在做为true
expiring = true;
setValid(false);
// Remove this session from our manager's active sessions
if (manager != null)
//删除该session实例
manager.remove(this);
//删除属性
String keys[] = keys();
for (int i = 0; i < keys.length; i++)
removeAttribute(keys[i], notify);
//触发session销毁事件
if (notify) {
fireSessionEvent(Session.SESSION_DESTROYED_EVENT, null);
}
//返回上下文
Context context = (Context) manager.getContainer();
Object listeners[] = context.getApplicationListeners();
if (notify && (listeners != null)) {
HttpSessionEvent event =
new HttpSessionEvent(getSession());
for (int i = 0; i < listeners.length; i++) {
int j = (listeners.length - 1) - i;
if (!(listeners[j] instanceof HttpSessionListener))
continue;
HttpSessionListener listener =
(HttpSessionListener) listeners[j];
try {
fireContainerEvent(context,
"beforeSessionDestroyed",
listener);
//销毁session
listener.sessionDestroyed(event);
fireContainerEvent(context,
"afterSessionDestroyed",
listener);
} catch (Throwable t) {
try {
fireContainerEvent(context,
"afterSessionDestroyed",
listener);
} catch (Exception e) {
;
}
// FIXME - should we do anything besides log these?
log(sm.getString("standardSession.sessionEvent"), t);
}
}
}
// 销毁session过程执行完毕
expiring = false;
if ((manager != null) && (manager instanceof ManagerBase)) {
recycle();
}
}
//将session置为非活跃
public void passivate() {
// 发送监听消息，触发session非活跃事件
HttpSessionEvent event = null;
String keys[] = keys();
for (int i = 0; i < keys.length; i++) {
Object attribute = getAttribute(keys[i]);
if (attribute instanceof HttpSessionActivationListener) {
if (event == null)
event = new HttpSessionEvent(this);
// FIXME: Should we catch throwables?
((HttpSessionActivationListener)attribute).sessionWillPassivate(event);
}
}
}
//激活session
public void activate() {
// Notify ActivationListeners
//触发session激活事件感兴趣的监听器，触发监听事件。
HttpSessionEvent event = null;
String keys[] = keys();
for (int i = 0; i < keys.length; i++) {
Object attribute = getAttribute(keys[i]);
if (attribute instanceof HttpSessionActivationListener) {
if (event == null)
event = new HttpSessionEvent(this);
// FIXME: Should we catch throwables?
((HttpSessionActivationListener)attribute).sessionDidActivate(event);
}
}
}
//返回内部制定名称的note信息
public Object getNote(String name) {
synchronized (notes) {
return (notes.get(name));
}
}
public Iterator getNoteNames() {
synchronized (notes) {
return (notes.keySet().iterator());
}
}
/**
*递归清除所有属性值，并恢复为初始值
*/
public void recycle() {
attributes.clear();
setAuthType(null);
creationTime = 0L;
expiring = false;
id = null;
lastAccessedTime = 0L;
maxInactiveInterval = -1;
notes.clear();
setPrincipal(null);
isNew = false;
isValid = false;
Manager savedManager = manager;
manager = null;
// Tell our Manager that this Session has been recycled
if ((savedManager != null) && (savedManager instanceof ManagerBase))
((ManagerBase) savedManager).recycle(this);
}
//删除note
public void removeNote(String name) {
synchronized (notes) {
notes.remove(name);
}
}
//删除session监听
public void removeSessionListener(SessionListener listener) {
synchronized (listeners) {
listeners.remove(listener);
}
}
//绑定对象到制定的名称上
public void setNote(String name, Object value) {
synchronized (notes) {
notes.put(name, value);
}
}
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("StandardSession[");
sb.append(id);
sb.append("]");
return (sb.toString());
}
//从特定的输入流读数据
void readObjectData(ObjectInputStream stream)
throws ClassNotFoundException, IOException {
readObject(stream);
}
//序列化session对象输出端到stream中
void writeObjectData(ObjectOutputStream stream)
throws IOException {
writeObject(stream);
}
public long getCreationTime() {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.getCreationTime.ise"));
return (this.creationTime);
}
/**
* Return the ServletContext to which this session belongs.
*/
//返回和session关联的容器（上下文）
public ServletContext getServletContext() {
if (manager == null)
return (null);
Context context = (Context) manager.getContainer();
if (context == null)
return (null);
else
return (context.getServletContext());
}
//获得session 关联的session上下文信息
public HttpSessionContext getSessionContext() {
if (sessionContext == null)
sessionContext = new StandardSessionContext();
return (sessionContext);
}
//获得属性名称
public Object getAttribute(String name) {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.getAttribute.ise"));
synchronized (attributes) {
return (attributes.get(name));
}
}
//获取属性的key值
public Enumeration getAttributeNames() {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.getAttributeNames.ise"));
synchronized (attributes) {
return (new Enumerator(attributes.keySet()));
}
}
public Object getValue(String name) {
return (getAttribute(name));
}
public String[] getValueNames() {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.getValueNames.ise"));
return (keys());
}
//将session实例设置为非法，解绑所有绑定在她上线的对象
public void invalidate() {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.invalidate.ise"));
// Cause this session to expire
expire();
}
public boolean isNew() {
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.isNew.ise"));
return (this.isNew);
}
public void putValue(String name, Object value) {
setAttribute(name, value);
}
public void removeAttribute(String name) {
removeAttribute(name, true);
}
//移除指定名称上绑定的属性对象
public void removeAttribute(String name, boolean notify) {
// Validate our current state
if (!expiring && !isValid)
throw new IllegalStateException
(sm.getString("standardSession.removeAttribute.ise"));
// Remove this attribute from our collection
Object value = null;
boolean found = false;
synchronized (attributes) {
found = attributes.containsKey(name);
if (found) {
value = attributes.get(name);
attributes.remove(name);
} else {
return;
}
}
//是否触发value解绑和属性移除操作
if (!notify) {
return;
}
//调用 valueUnbound()方法
HttpSessionBindingEvent event =
new HttpSessionBindingEvent((HttpSession) this, name, value);
if ((value != null) &&
(value instanceof HttpSessionBindingListener))
((HttpSessionBindingListener) value).valueUnbound(event);
//通知感兴趣的事件监听
Context context = (Context) manager.getContainer();
Object listeners[] = context.getApplicationListeners();
if (listeners == null)
return;
for (int i = 0; i < listeners.length; i++) {
if (!(listeners[i] instanceof HttpSessionAttributeListener))
continue;
HttpSessionAttributeListener listener =
(HttpSessionAttributeListener) listeners[i];
try {
fireContainerEvent(context,
"beforeSessionAttributeRemoved",
listener);
//移除属性
listener.attributeRemoved(event);
fireContainerEvent(context,
"afterSessionAttributeRemoved",
listener);
} catch (Throwable t) {
try {
fireContainerEvent(context,
"afterSessionAttributeRemoved",
listener);
} catch (Exception e) {
;
}
// FIXME - should we do anything besides log these?
log(sm.getString("standardSession.attributeEvent"), t);
}
}
}
//移除某名称的值
public void removeValue(String name) {
removeAttribute(name);
}
//为属性数组添加key,value
public void setAttribute(String name, Object value) {
// Name cannot be null
if (name == null)
throw new IllegalArgumentException
(sm.getString("standardSession.setAttribute.namenull"));
// Null value is the same as removeAttribute()
if (value == null) {
removeAttribute(name);
return;
}
// Validate our current state
if (!isValid)
throw new IllegalStateException
(sm.getString("standardSession.setAttribute.ise"));
if ((manager != null) && manager.getDistributable() &&
!(value instanceof Serializable))
throw new IllegalArgumentException
(sm.getString("standardSession.setAttribute.iae"));
// Replace or add this attribute
Object unbound = null;
synchronized (attributes) {
unbound = attributes.get(name);
attributes.put(name, value);
}
// 触发HttpSessionBindingListener监听
if ((unbound != null) &&
(unbound instanceof HttpSessionBindingListener)) {
((HttpSessionBindingListener) unbound).valueUnbound
(new HttpSessionBindingEvent((HttpSession) this, name));
}
// Call the valueBound() method if necessary
HttpSessionBindingEvent event = null;
if (unbound != null)
event = new HttpSessionBindingEvent
((HttpSession) this, name, unbound);
else
event = new HttpSessionBindingEvent
((HttpSession) this, name, value);
if (value instanceof HttpSessionBindingListener)
((HttpSessionBindingListener) value).valueBound(event);
// Notify interested application event listeners
Context context = (Context) manager.getContainer();
Object listeners[] = context.getApplicationListeners();
if (listeners == null)
return;
for (int i = 0; i < listeners.length; i++) {
if (!(listeners[i] instanceof HttpSessionAttributeListener))
continue;
HttpSessionAttributeListener listener =
(HttpSessionAttributeListener) listeners[i];
try {
if (unbound != null) {
fireContainerEvent(context,
"beforeSessionAttributeReplaced",
listener);
//属性值变更
listener.attributeReplaced(event);
fireContainerEvent(context,
"afterSessionAttributeReplaced",
listener);
} else {
fireContainerEvent(context,
"beforeSessionAttributeAdded",
listener);
//属性值添加
listener.attributeAdded(event);
fireContainerEvent(context,
"afterSessionAttributeAdded",
listener);
}
} catch (Throwable t) {
try {
if (unbound != null) {
fireContainerEvent(context,
"afterSessionAttributeReplaced",
listener);
} else {
fireContainerEvent(context,
"afterSessionAttributeAdded",
listener);
}
} catch (Exception e) {
;
}
// FIXME - should we do anything besides log these?
log(sm.getString("standardSession.attributeEvent"), t);
}
}
}
//从指定输入流中读序列化信息
private void readObject(ObjectInputStream stream)
throws ClassNotFoundException, IOException {
// Deserialize the scalar instance variables (except Manager)
authType = null; // Transient only
creationTime = ((Long) stream.readObject()).longValue();
lastAccessedTime = ((Long) stream.readObject()).longValue();
maxInactiveInterval = ((Integer) stream.readObject()).intValue();
isNew = ((Boolean) stream.readObject()).booleanValue();
isValid = ((Boolean) stream.readObject()).booleanValue();
thisAccessedTime = ((Long) stream.readObject()).longValue();
principal = null; // Transient only
// setId((String) stream.readObject());
id = (String) stream.readObject();
if (debug >= 2)
log("readObject() loading session " + id);
// Deserialize the attribute count and attribute values
if (attributes == null)
attributes = new HashMap();
int n = ((Integer) stream.readObject()).intValue();
boolean isValidSave = isValid;
isValid = true;
for (int i = 0; i < n; i++) {
String name = (String) stream.readObject();
Object value = (Object) stream.readObject();
if ((value instanceof String) && (value.equals(NOT_SERIALIZED)))
continue;
if (debug >= 2)
log(" loading attribute '" + name +
"' with value '" + value + "'");
synchronized (attributes) {
attributes.put(name, value);
}
}
isValid = isValidSave;
}
//写数据到输出流中
private void writeObject(ObjectOutputStream stream) throws IOException {
// Write the scalar instance variables (except Manager)
stream.writeObject(new Long(creationTime));
stream.writeObject(new Long(lastAccessedTime));
stream.writeObject(new Integer(maxInactiveInterval));
stream.writeObject(new Boolean(isNew));
stream.writeObject(new Boolean(isValid));
stream.writeObject(new Long(thisAccessedTime));
stream.writeObject(id);
if (debug >= 2)
log("writeObject() storing session " + id);
// Accumulate the names of serializable and non-serializable attributes
String keys[] = keys();
ArrayList saveNames = new ArrayList();
ArrayList saveValues = new ArrayList();
for (int i = 0; i < keys.length; i++) {
Object value = null;
synchronized (attributes) {
value = attributes.get(keys[i]);
}
if (value == null)
continue;
else if (value instanceof Serializable) {
saveNames.add(keys[i]);
saveValues.add(value);
}
}
// Serialize the attribute count and the Serializable attributes
int n = saveNames.size();
stream.writeObject(new Integer(n));
for (int i = 0; i < n; i++) {
stream.writeObject((String) saveNames.get(i));
try {
stream.writeObject(saveValues.get(i));
if (debug >= 2)
log(" storing attribute '" + saveNames.get(i) +
"' with value '" + saveValues.get(i) + "'");
} catch (NotSerializableException e) {
log(sm.getString("standardSession.notSerializable",
saveNames.get(i), id), e);
stream.writeObject(NOT_SERIALIZED);
if (debug >= 2)
log(" storing attribute '" + saveNames.get(i) +
"' with value NOT_SERIALIZED");
}
}
}
// -------------------------------------------------------- Private Methods
/**
* Fire container events if the Context implementation is the
* <code>org.apache.catalina.core.StandardContext</code>.
*
* @param context Context for which to fire events
* @param type Event type
* @param data Event data
*
* @exception Exception occurred during event firing
*/
private void fireContainerEvent(Context context,
String type, Object data)
throws Exception {
if (!"org.apache.catalina.core.StandardContext".equals
(context.getClass().getName())) {
return; // Container events are not supported
}
// NOTE: Race condition is harmless, so do not synchronize
if (containerEventMethod == null) {
containerEventMethod =
context.getClass().getMethod("fireContainerEvent",
containerEventTypes);
}
Object containerEventParams[] = new Object[2];
containerEventParams[0] = type;
containerEventParams[1] = data;
containerEventMethod.invoke(context, containerEventParams);
}
/**
* Notify all session event listeners that a particular event has
* occurred for this Session. The default implementation performs
* this notification synchronously using the calling thread.
*
* @param type Event type
* @param data Event data
*/
public void fireSessionEvent(String type, Object data) {
if (listeners.size() < 1)
return;
SessionEvent event = new SessionEvent(this, type, data);
SessionListener list[] = new SessionListener[0];
synchronized (listeners) {
list = (SessionListener[]) listeners.toArray(list);
}
for (int i = 0; i < list.length; i++)
((SessionListener) list[i]).sessionEvent(event);
}
//属性中的key值
private String[] keys() {
String results[] = new String[0];
synchronized (attributes) {
return ((String[]) attributes.keySet().toArray(results));
}
}
//关联他的日志实例打印日志
private void log(String message) {
if ((manager != null) && (manager instanceof ManagerBase)) {
((ManagerBase) manager).log(message);
} else {
System.out.println("StandardSession: " + message);
}
}
//打印错误日志信息
private void log(String message, Throwable throwable) {
if ((manager != null) && (manager instanceof ManagerBase)) {
((ManagerBase) manager).log(message, throwable);
} else {
System.out.println("StandardSession: " + message);
throwable.printStackTrace(System.out);
}
}
}
//该类是HttpSessionContext的假实现，为了满足HttpSession.getSessionContext()调用返回值信息。
final class StandardSessionContext implements HttpSessionContext {
private HashMap dummy = new HashMap();
//返回所有的sessionid信息 数据按照Enumeration类型返回
public Enumeration getIds() {
return (new Enumerator(dummy));
}
public HttpSession getSession(String id) {
return (null);
}
}
未完待续