Hasor 自定義作用域

我們以 HttpSession 為例，通過實(shí)際例子向大家展示。如何通過Hasor Scope 實(shí)現(xiàn)一個 HttpSession 作用域。

public class SessionScope implements Scope{
    private static final ThreadLocal<HttpSession> session 
        = new ThreadLocal<HttpSession>();

    public <T> Provider<T> scope(Object key, Provider<T> provider) {
        HttpSession httpSession = session.get();
        if (httpSession == null) {
            return provider;
        }
        String keyStr = "session_scope_" + key.toString();
        Object attribute = httpSession.getAttribute(keyStr);
        Provider<T> finalProvider = provider;
        if (attribute == null) {
            httpSession.setAttribute(keyStr, provider);
        } else {
            finalProvider = (Provider<T>) httpSession.getAttribute(keyStr);
        }
        return finalProvider;
    }
}

在例子中為了避免保存到 Session 中的 Bean 和本身 Session 中的數(shù)據(jù) key 出現(xiàn)沖突，我們特意加了一個前綴用于區(qū)分。

現(xiàn)在作用域的功能是有了，但是我們的 HttpSession 對象的還沒有做初始化。這次我們來實(shí)現(xiàn) Filter 接口，在每次 request 請求到來的時候把 Session 都更新到 ThreadLocal 中。在訪問結(jié)束之后再把 ThreadLocal 清理掉。

下面來看改造了之后的 Scope 代碼：

public class SessionScope implements Scope, Filter {
    private static final ThreadLocal<HttpSession> session
     = new ThreadLocal<HttpSession>();

    public void init(FilterConfig filterConfig) { ... }
    public void destroy() { ... }
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
        try {
            if (session.get() != null) {
                session.remove();
            }
            session.set(((HttpServletRequest) request).getSession(true));
            chain.doFilter(request, response);
        } finally {
            if (session.get() != null) {
                session.remove();
            }
        }
    }

    public <T> Provider<T> scope(Object key, Provider<T> provider) {
        HttpSession httpSession = session.get();
        if (httpSession == null) {
            return provider;
        }
        String keyStr = "session_scope_" + key.toString();
        Object attribute = httpSession.getAttribute(keyStr);
        Provider<T> finalProvider = provider;
        if (attribute == null) {
            httpSession.setAttribute(keyStr, provider);
        } else {
            finalProvider = (Provider<T>) httpSession.getAttribute(keyStr);
        }
        return finalProvider;
    }
}

從上面例子代碼中看到進(jìn)入 filter 時做了 Session 的初始化將其保存到 ThreadLocal ，離開之后又把 ThreadLocal 清理掉。

最后我們在 Hasor 初始化的時候把 Scope 配置到 Hasor 中：

public class StartModule extends WebModule {
    public void loadModule(WebApiBinder apiBinder) throws Throwable {
        ...
        SessionScope scope = new SessionScope();
        apiBinder.filter("/*").through(0, scope);
        apiBinder.registerScope("session", scope);
        ...
    }
}

接下來使用這個 Scope：

apiBinder.bindType(UserInfo.class).toScope(new SessionScope());
//or
apiBinder.bindType(UserInfo.class).toScope("session");