如何在过滤器中获取 servlet 的元信息？

Question

我想以声明的方式向 servlet 方法添加权限，例如：

// servlet
@Perms("admin", "finance")
public void doPost(servletRequest req, servletResponse res) {
   ...
}

// web filter
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
   List<String> allowedRoles = ... // somehow get values from @Perms
}

可能有一些其他方法可以在没有注释的情况下做到这一点，这只是我想做的想法的例子。

或者更抽象的例子：

@WebServlet("/someaddress")

// servlet
@What("have a nice day")
public void doPost(servletRequest req, servletResponse res) {
   ...
}

@WebFilter("/*")
// web filter
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
   String msg = ... // somehow get values from @What
}

Answer 1

这是解决方案

声明注解

@Retention(RetentionPolicy.RUNTIME)
public @interface What {
    String[] value();
}

覆盖 servlet 中的 init 方法（我认为声明另一个 class 将很有用，所有 servlet 都将继承该 init）

    @Override
    public void init() throws ServletException {
        ServletContext ctx = this.getServletContext();
        final Class[] sFormalArgs = {HttpServletRequest.class,HttpServletResponse.class};
        try {
            Method m = this.getClass().getDeclaredMethod("doGet", sFormalArgs); // do the same with other methods
            What a = m.getAnnotation(What.class);
            String[] value = a.value();
            ctx.setAttribute("someStuff", value);

        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }

给方法添加注解

    @What({"admin", "finance"})
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
    {
        ....
    }

在网络过滤器中获取它

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain
    ) {
        HttpServletRequest req = (HttpServletRequest) servletRequest;
        ServletContext ctx = req.getServletContext();
        Object o = ctx.getAttribute("someStuff");
    }

不要忘记处理错误和多线程问题

如何在过滤器中获取 servlet 的元信息？

ways to get meta info of servlet in filter?

java

servlets