使用ThreadLocal保存用户登录信息

最近在使用WebSocket来进行消息推送，一，系统推送。二，用户对用户进行推送。

SystemSession类：

import com.srkj.code.model.User;
/**
 * 线程共享类
 * @author 胡汉三 
 *
 * 2014-11-18 下午2:40:27
 */
public class SystemSession {
	//声明
	private static ThreadLocal<User> local = new ThreadLocal<User>();  
	/**
	 * 赋值
	 * @param session
	 */
    public static void set(User session) {  
        local.set(session);  
    }  
    /**
     * 取值
     * @return
     */
    public static User get() {  
        return local.get();  
    }    
    /**
     * 移除
     */
    public static void remove(){
    	local.remove();
    }
}

使用过滤器拦截用户请求：

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import com.srkj.code.model.User;
/**
 * Session过滤器
 * @author 胡汉三
 *
 * 2014-11-18 下午2:41:35
 */
public class MyFilter implements Filter{

	public void destroy() {}
	
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain filterChain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest)req;  
	    User userSession = (User)request.getSession().getAttribute("userInfo");  
	    if (userSession != null) {  
	    	//重新设值session
	        request.getSession().setAttribute("userInfo", userSession);  
	    }    
	    filterChain.doFilter(req, res);    
		
	}

	public void init(FilterConfig arg0) throws ServletException {}
	
}

web.xml配置：

<filter>
        <filter-name>myFilter</filter-name>
        <filter-class>com.srkj.code.util.MyFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>myFilter</filter-name> 
        <url-pattern>/*</url-pattern>
    </filter-mapping>

在配置一个用户session状态变更的监听类MyHttpSessionAttributeListener：

import javax.servlet.http.HttpSessionAttributeListener;
import javax.servlet.http.HttpSessionBindingEvent;

import com.srkj.code.model.User;
/**
 * Session监听器
 * @author 胡汉三
 * 
 * 2014-11-18 下午2:42:02
 */
public class MyHttpSessionAttributeListener implements HttpSessionAttributeListener {  
	/**
	 * 添加Session
	 */
	public void attributeAdded(HttpSessionBindingEvent event) {  
        if ("userInfo".equals(event.getName())) {  
            SystemSession.set((User)event.getValue());  
        }  
    }  
  
	/**
	 * 替代Session
	 */
    public void attributeReplaced(HttpSessionBindingEvent event) {  
        if ("userInfo".equals(event.getName())) {  
            SystemSession.set((User)event.getValue());  
        }  
    }

    /**
     * 销毁Session
     */
	public void attributeRemoved(HttpSessionBindingEvent event) {
		if("userInfo".equals(event.getName())){
			SystemSession.remove();  
		}  
	}     
}

web.xml监听配置：

<listener>
		<listener-class>com.srkj.code.util.MyHttpSessionAttributeListener</listener-class>
	 </listener>

这样之后，就可以在程序中直接SystemSession.get() 就能得到用户对象，如：

public ChatAnnotation() {
		nickname = SystemSession.get().getUuuid();  
	}