java - 将 request 属性从 request 注入(inject)到 spring Controller 方法中

Question

我有一些 spring @RestControllers 方法，我想将每个请求附带的值作为请求属性(包含用户)注入(inject)，例如:

@RestController
@RequestMapping("/api/jobs")
public class JobsController {
     // Option 1 get user from request attribute as prop somehow
     private String userId = "user1";

    // Option 2 inject into method using aspect or something else
    @RequestMapping(value = "", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<List<Jobs>> getJobs() throws ResourceNotFoundException {
       // currentUser is injected 
       this.getJobs(currentUser);
}

我知道我能做到:

@RestController
@RequestMapping("/api/jobs")
public class JobsController {

    @RequestMapping(value = "", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<List<Jobs>> getJobs(HttpServletRequest request) throws ResourceNotFoundException { 
       String currentUser = null;
       if (request.getAttribute("subject") != null) {
           currentUser = request.getAttribute("subject").toString();
       }
       this.getJobs(currentUser);
}

但这需要我在程序中的每个方法中添加此代码，在我看来，这是一个非常糟糕的做法。
有办法实现我想要的吗？

如果答案确实需要方面，那么代码示例将非常感激，因为我只阅读了它，但从未真正对方面做过任何事情。

更新
我建议的代码可以使用以下内容进行简化:

@RestController
@RequestMapping("/api/jobs")
public class JobsController {

    @RequestMapping(value = "", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<List<Jobs>> getJobs(@Value("#{request.getAttribute('subject')}" String currentUser) throws ResourceNotFoundException { 
       this.getJobs(currentUser);
}

但仍然要求我在每个方法中添加该参数。这个参数可以以某种方式注入(inject)到每个方法中吗？

Answer 1

您可以使用Filter填充 ThreadLocal<String>存储该属性的变量:

public class MyFilter implements Filter {

  @Override
  public void init(FilterConfig filterConfig) throws ServletException {}

  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    throws IOException, ServletException {
    HttpServletRequest req = (HttpServletRequest) request;
    ContextHolder.setSubject(request.getAttribute('subject'));
    chain.doFilter(request, response);
  }

  @Override
  public void destroy() {
    ContextHolder.removeSubject();
  }
}


public class ContextHolder {

  private static final ThreadLocal<String> SUBJECT = new ThreadLocal<String>() {
    @Override
    protected String initialValue() {
      return "empty";
    }
  };

  public static void setSubject(String subject) {
    SUBJECT.set(subject);
  }

  public static String getSubject() {
    return SUBJECT.get();
  }

  public static void removeSubject() {
    SUBJECT.remove();
  }
}

过滤器将配置为拦截所有请求并填充 SUBJECT多变的。通过使用 ThreadLocal ，确保每个线程都有自己的 subject值(value)。现在，您可以通过调用 ContextHolder.getSubject() 在应用程序中的任何位置获取该值。 :

  @RequestMapping(value = "", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
  public ResponseEntity<List<Jobs>> getJobs(HttpServletRequest request) throws ResourceNotFoundException { 
    this.getJobs(ContextHolder.getSubject());
  }

您还必须注册 Filter在 web.xml 文件中:

<filter>
    <filter-name>MyFilter</filter-name>
    <filter-class>com.MyFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>MyFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

如果您有多个属性，您可以使用 ThreadLocal<Map<String, String>>而是变量。