springboot中action綁定ServletRequest的attirbute的值傳參

有些時候需要在後臺處理一封裝一些參數送到action中便於業務處理.比於app中的token驗證,
根據token查找到對應的用戶信息。比如分佈式框架中獲取用戶信息等.springboot中可以自
定義參數解析器來綁定參數，通過它可以拿到ServletRequest中的attirbute中的值進行參數
綁定。

自定義一個annotation,通過這個註解中的 name查找attribute中的key對應的值 

import java.lang.annotation.ElementType;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

@Target(ElementType.PARAMETER)

@Retention(RetentionPolicy.RUNTIME)

public @interface AttributeResolve {

String name() default "user";

}

自定義一個解析器類

import javax.servlet.http.HttpServletRequest;

import org.springframework.core.MethodParameter;

import org.springframework.web.bind.support.WebDataBinderFactory;

import org.springframework.web.context.request.NativeWebRequest;

import org.springframework.web.method.support.HandlerMethodArgumentResolver;

import org.springframework.web.method.support.ModelAndViewContainer;

public class AttributeArgumentResolver implements HandlerMethodArgumentResolver{

@Override

public Object resolveArgument(MethodParameter arg0, ModelAndViewContainer arg1, NativeWebRequest arg2,

WebDataBinderFactory arg3) throws Exception {

// TODO Auto-generated method stub

 Object resultObj=null;

  AttributeResolve mp =  arg0.getParameterAnnotation(AttributeResolve.class);

  if(mp!=null) {

 String attributeName= mp.name();

 HttpServletRequest request = arg2.getNativeRequest(HttpServletRequest.class);

 resultObj = request.getAttribute(attributeName);

  }

return resultObj;

}

@Override

public boolean supportsParameter(MethodParameter arg0) {

// TODO Auto-generated method stub

return  arg0.hasParameterAnnotation(AttributeResolve.class);

}

springboot中註冊自定義的參數解析器

@Configuration

public class MyWebMvcConfig extends WebMvcConfigurerAdapter{

public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {

        argumentResolvers.add(new AttributeArgumentResolver());

    }
}


使用方法.
需要在action調用前向HttpServletRequest中的attribute中注入值 ，可以自定義一個filter,在filter中進行處理
如在filter中處理app傳過來的token驗證後取得對應的用戶信息等.下面例子簡單放入一個對象

@WebFilter(filterName = "axssFilter", urlPatterns = "/*",

initParams = {

@WebInitParam(name = "ignores", value = "*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/druid/*")// 忽略資源

}

)

public class XssFilter implements javax.servlet.Filter{

private Set<String> prefixIignores = new HashSet<String>();

@Override

public void destroy() {

// TODO Auto-generated method stub

}

@Override

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)

throws IOException, ServletException {

// TODO Auto-generated method stub

HttpServletRequest request = (HttpServletRequest) req;

HttpServletResponse response = (HttpServletResponse) res;

             Blogger user = new Blogger();

          user.setUsername("asfdasdf");

         request.setAttribute("user", user);

               chain.doFilter(request, response);  

}

}

action獲取attribute中放入的對象

        @RequestMapping("/index")

public String index(@AttributeResolve(name="user") Bloggerbh, HttpServletRequest request,Model model) 

嗯，還算優雅