我试图在一个名为 Display.java 的类中理解以下代码：
Map<String,Object> context = (Map<String,Object>) globalSession.get("cascadas.ace.context");
if(context != null) {
dresscode = (String) context.get("dresscode");
hobby = (String) context.get("hobby");
}
if ((hobby == null) || (dresscode == null)) {
SystemConfiguration.getInstance().getLog().warning("Advertisement display: dresscode and/or hobby not available, no image will be displayed.");
}
正在发生的事情是有一个 GUI 窗口，允许您为着装要求和爱好选择单选按钮。但是不知何故，当我在程序文本中添加另一个虚拟单选按钮时（在与 Display.java 位于同一文件夹中的类中，称为 ContextSimulatorGUI ，它甚至不显示 GUI 窗口.. ，我在控制台中看到以下内容：
Advertisement display: dresscode and/or hobby not available, no image will be displayed."
关于globalSession变量..它是一个“会话”对象；在项目中有一个名为 的类Session，如下所示：
/* * ACE Autonomic Toolkit *（又名 CASCADAS ACE Toolkit）* * 由 CASCADAS 项目工作包 1 创建：* - 布达佩斯科技与经济大学 * - 弗劳恩霍夫研究所 FOKUS * - 意大利电信实验室 * - 卡塞尔大学 * - 卡塞尔大学摩德纳和雷焦艾米利亚 * * 更多信息请访问： * - http://acetoolkit.sourceforge.net
* - http://cascadas-project.org
*
* The authors would like to acknowledge the European Commission
* for funding the Integrated Project CASCADAS Component-ware for
* Autonomic, Situation-aware Communications, And Dynamically
* Adaptable Services (FET Proactive Initiative, IST-2004-2.3.4
* Situated and Autonomic Communications) within the 6th IST Framework
* Program. The authors also wish to thank other project Partners for
* the fruitful cooperation within the project.
*/
package cascadas.ace.session;
import java.io.Serializable;
import java.util.Map;
/**
* Interface describing the session context.
*/
// TODO: use generics for type safety stuff?
public interface Session extends Serializable {
/**
* Returns the name of the SessionContext.
*
* @return the name
*/
public String getName();
/**
* Removes the key-value pair from the session.
* @param key param name
*/
public void remove(String key);
/**
* Returns the current state.
*
* @return curretn state
*/
// public State getState();
/**
* Sets the current state.
*
* @param s the state
*/
// public void setState(State s);
/**
* Returns the contract with the specified id.
*
* @param contract id
* @return contract
* @throws SessionContextNotFoundException if contract is not found
*/
// public Contract getContract(String id) throws SessionNotFoundException;
/**
* Adds a contract with the given id. Id must be unique.
*
* @param s the state
*/
// public void addContract(String id, Contract c);
/**
* Returns all contracts.
*
* @return id-->contract map
*/
// public Map<String,Contract> getAllContracts();
/**
* Puts a piece of data to the session context.
* Overwrites existing data with teh same name.
*
* @param id name of the data
* @param value value of the data
*/
public void put( String id, Object value ) throws SessionException;
/**
* Puts an integer value into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, int value );
/**
* Puts a double value into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, double value );
/**
* Puts a float into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, float value );
/**
* Puts a long value into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, long value );
/**
* Puts a short value into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, short value );
/**
* Puts a char into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, char value );
/**
* Puts a boolean value into the session context.
*
* @param id name
* @param value value
*/
public void put ( String id, boolean value );
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @return the data as an Object or null if not found
*/
public Object get (String id) ;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as an integer or 0 if not found
*/
public int getInt ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a double
*/
public double getDouble ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a float
*/
public float getFloat ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a long
*/
public long getLong ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a short
*/
public short getShort ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a char
*/
public char getChar ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a boolean
*/
public boolean getBoolean ( String id) throws SessionException;
/**
* Returns the matching data from the session context.
*
* @param id name of the data
* @throws cascadas.ace.reasoner.SessionContextException
* if an error occurs
* @return the data as a String
*/
public String getString ( String id) throws SessionException;
/**
* Returns all data as a set.
* @return all data in the session context
*/
public Map<String,Object> getAllData();
/**
* Sets the ace name (for debug messages).
* @param aceName ace name
*/
public void setAceName(String aceName);
}
..etc（顺便说一句，我知道源代码有点草率，但它是一些开源项目，而不是我的代码）。
所以总结一下，我主要想了解最上面的代码，最下面的东西是上下文。我希望这不会令人困惑 - 我感谢任何提示或建议。