从OncePerRequestFilter访问spring bean [英] Access to spring beans from OncePerRequestFilter

问题描述

我想从OncePerRequestFilter类访问一个spring组件，但是访问服务时得到的是空指针，我认为原因是配置. 我认为由于配置，过滤器在spring调度程序servlet之前被调用.有什么好办法可以做到这一点，请提出建议.

I want to access a spring component from OncePerRequestFilter class, but I am getting null pointer when I access service, and I think the reason for that is the configuration. I think the filter is getting called before the spring dispatcher servlet due to the configuration. Any good way to get this done, suggestions please.

<servlet>
    <servlet-name>SpringDispatcherServer</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/config/springConfig.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>SpringDispatcherServer</servlet-name>
    <url-pattern>/test/api/*</url-pattern>
</servlet-mapping>

<filter>
  <filter-name>AuthCheck</filter-name>
  <filter-class>org.test.util.AuthCheckFilter</filter-class>
</filter>    
<filter-mapping>
  <filter-name>AuthCheck</filter-name>
  <url-pattern>/test/api/*</url-pattern>
</filter-mapping>`

public class AuthCheckFilter extends OncePerRequestFilter 
{
@Autowired
private AuthCheckService authCheckService;

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
log.info("authCheckService"+authCheckService);

，并且记录器为"authCheckService"输出null

and the logger prints null for "authCheckService"

推荐答案

您的过滤器是在Spring容器外部配置的.因此，不会注入您的@Autowired依赖项.

You filter is being configured outside the Spring container. Hence your @Autowired dependency is not injected.

要使您的Filter bean由Spring管理，而又不建议通过使用SpringBeanAutowiringSupport将其紧密耦合到Spring基础结构，则可以使用DelegatingFilterProxy抽象

To have your Filter bean managed by Spring without also tightly coupling it to Spring infrastructure through the use of SpringBeanAutowiringSupport suggested , you can use the DelegatingFilterProxy abstraction

在您的应用程序上下文中将AuthCheckFilter过滤器定义为bean，例如

Define AuthCheckFilter filter as a bean in your application context e.g

@Bean
public Filter authCheckFilter(){
     AuthCheckFilter filter = new AuthCheckFilter();
     //supply dependencies
     return filter;
}

然后在web.xml中将过滤器类指定为org.springframework.web.filter.DelegatingFilterProxy，并且过滤器名称必须与上下文中的authCheckFilter bean名称匹配

Then in your web.xml specify your filter with filter-class as org.springframework.web.filter.DelegatingFilterProxy and the filter name must match the authCheckFilter bean name in the context

在运行时，DelegatingFilterProxy过滤器将委派给上下文中名称为AuthCheckFilter的完全配置的bean(必须为过滤器)

At runtime DelegatingFilterProxy filter will delegate to a fully configured bean with the name authCheckFilter in the context (which must be a Filter)

<filter>
  <filter-name>authFilterCheck</filter-name>
  <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>    
<filter-mapping>
  <filter-name>authCheckFilter</filter-name>
  <url-pattern>/test/api/*</url-pattern>
</filter-mapping>

通过此设置，您不必担心筛选器，根上下文或servlet的生命周期

With this setup you wont have to worry about the lifecyles of your filter , root context or servlet

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