英文:
ways to get meta info of servlet in filter?
问题
我想以声明方式向servlet方法添加权限，例如：
// servlet@Perms("admin", "finance")public void doPost(ServletRequest req, ServletResponse res) {...}
// web过滤器public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {List<String> allowedRoles = ... // 以某种方式从@Perms获取值}
也许还有其他的方法可以在没有注解的情况下实现，这只是我想要做的思路示例。
更抽象的示例：
@WebServlet("/someaddress")// servlet@What("have a nice day")public void doPost(ServletRequest req, ServletResponse res) {...}
@WebFilter("/*")// web过滤器public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {String msg = ... // 以某种方式从@What获取值}
英文:
I want to add permissions to servlet methods in declarative way, for example:
// servlet@Perms("admin", "finance")public void doPost(servletRequest req, servletResponse res) {...}
// web filterpublic void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {List<String> allowedRoles = ... // somehow get values from @Perms}
May be there is some other ways to do it without annotations, it is just example of idea what I want to do.
Or more abstract example:
@WebServlet("/someaddress")// servlet@What("have a nice day")public void doPost(servletRequest req, servletResponse res) {...}
@WebFilter("/*")// web filterpublic void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {String msg = ... // somehow get values from @What}
答案1
得分: 0
Here is the translated content:
- 声明注解
@Retention(RetentionPolicy.RUNTIME)public @interface What {String[] value();}
- 覆盖 servlet 中的
init方法（我认为声明另一个所有 servlet 都将继承其init方法的类会很有用）
@Overridepublic void init() throws ServletException {ServletContext ctx = this.getServletContext();final Class[] sFormalArgs = {HttpServletRequest.class, HttpServletResponse.class};try {Method m = this.getClass().getDeclaredMethod("doGet", sFormalArgs); // 对其他方法也做同样的操作What a = m.getAnnotation(What.class);String[] value = a.value();ctx.setAttribute("someStuff", value);} catch (NoSuchMethodException e) {e.printStackTrace();}}
- 在方法中添加注解
@What({"admin", "finance"})@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) {....}
- 在 web 过滤器中获取它
@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) {HttpServletRequest req = (HttpServletRequest) servletRequest;ServletContext ctx = req.getServletContext();Object o = ctx.getAttribute("someStuff");}
请不要忘记处理错误和多线程问题。
英文:
Here is solution
- declare annotation
@Retention(RetentionPolicy.RUNTIME)public @interface What {String[] value();}
- override
initmethod in servlet (I think it will be usefull to declare another class that all servlet will be inherit with thatinit)
@Overridepublic 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 methodsWhat a = m.getAnnotation(What.class);String[] value = a.value();ctx.setAttribute("someStuff", value);} catch (NoSuchMethodException e) {e.printStackTrace();}}
- add annotation to method
@What({"admin", "finance"})@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp){....}
- get it in web filter
@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) {HttpServletRequest req = (HttpServletRequest) servletRequest;ServletContext ctx = req.getServletContext();Object o = ctx.getAttribute("someStuff");}
do not forget to handle errors and multithreding issues
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