DAO层和Service层访问session

  多情况下，我们需要在DAO或者Service层拿到Session中的值，比如下面这个应用，session中存放了当前用户的账号，在DAO层中需要insert一条record，这条record需要记录当前用户（该记录是由谁创建的），对于这样的应用，我们一般可以在Action层中通过request拿到session里的用户账号，然后传入service,再传入DAO层，就可以解决了。

    今天，我在这里记录一种方式，利用ThreadLocal来存入sesion,然后可以在任何业务层，DAO层获取Session的方式，首先建立一个CSession来存放session的值，只放了2个属性，用户的账号和姓名

public class CSession {
    private String username;
    private String userId;

    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }

    public String getUserId() {
        return userId;
    }
    public void setUserId(String userId) {
        this.userId = userId;
    }
}

public class CSession {
	private String username;
	private String userId;
		
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	
	public String getUserId() {
		return userId;
	}
	public void setUserId(String userId) {
		this.userId = userId;
	}
}

建立SessionUser类，用来存放在整个运行期CSession的存在

public class SessionUser {


    @SuppressWarnings("unchecked")
    static ThreadLocal sessionUser =
new ThreadLocal();

    @SuppressWarnings("unchecked")
    public static
void setSessionUser(CSession cSession) {
        sessionUser.set(cSession);
    }

    public static CSession getSessionUser(){
        return (CSession )sessionUser.get();
    }

    public static String getSessionUserId(){
        return getSessionUser().getUserId();
    }

    public static String getSessionUserName(){
        return getSessionUser().getUsername();
    }
}

public class SessionUser {


	@SuppressWarnings("unchecked")
	static ThreadLocal sessionUser = new ThreadLocal();
	
	@SuppressWarnings("unchecked")
	public static void setSessionUser(CSession cSession) {
		sessionUser.set(cSession);
	}
	
	public static CSession getSessionUser(){
		return (CSession )sessionUser.get();
	}
	
	public static String getSessionUserId(){
		return getSessionUser().getUserId();
	}
	
	public static String getSessionUserName(){
		return getSessionUser().getUsername();
	}
}

在登录的Action里，登录成功后，加Session里的用户信息，放入CSession中，

HttpSession session = request.getSession(true);
CSession cs = new CSession();
cs.setUserId(userId);
cs.setUsername(userName);
session.setAttribute("C_SESSION",cs);

HttpSession session = request.getSession(true);
CSession cs = new CSession();
cs.setUserId(userId);
cs.setUsername(userName);
session.setAttribute("C_SESSION",cs);

最后，在session check的Filter中，把CSession注入到SessionUser中，

public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {

        HttpServletRequest hrequest = (HttpServletRequest) request;
        HttpServletResponse hresponse = (HttpServletResponse) response;

               .......

        CSession cs = (CSession) hrequest.getSession(true).getAttribute("C_SESSION");

        SessionUser.setSessionUser(cs);

                .......
    }

public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest hrequest = (HttpServletRequest) request;
		HttpServletResponse hresponse = (HttpServletResponse) response;
		
               .......
		
		CSession cs = (CSession) hrequest.getSession(true).getAttribute("C_SESSION");
		
		SessionUser.setSessionUser(cs);
						
                .......
	}

下面我们就可以再DAO层中直接从SessionUser中获取 userid 和 username,

xxxTO.setUserId(SessionUser.getSessionUserId());
xxxTO.setUserName(SessionUser.getSessionUserName());

xxxTO.setUserId(SessionUser.getSessionUserId());
xxxTO.setUserName(SessionUser.getSessionUserName());

页面上，

<bean:write name="C_SESSION" property="username"/>
<bean:write name="C_SESSION" property="userId"/>

<bean:write name="C_SESSION" property="username"/>
<bean:write name="C_SESSION" property="userId"/>