陷入了一個(gè)奇怪的要求.我需要在log4j消息上附加唯一的錯(cuò)誤ID并將該消息ID返回到接口.因此,盡管如此,我還是創(chuàng)建了一個(gè)spring服務(wù),如下所示

public class LoggingService {

   protected static Logger logger = LoggerFactory.getLogger(LoggingService.class);



   public String debug(String debug_msg)
   {
       String uniqueMsgId = generateUniqueId();
       logger.debug(concatIdWithMsg(uniqueMsgId, debug_msg));
       return uniqueMsgId;
   }

  }

并將其自動(dòng)連線到我需要的任何地方.

 public class LoginLogoutController {

    @Autowired
    LoggingService logger;

    @RequestMapping(value = "/login", method = RequestMethod.GET)
    public String getLoginPage()
    {
       logger.debug("Login page requested");
    }
    }

盡管它工作正常,但記錄器msg中的源類是LoggingService,這很明顯.我想要的是傳遞LoggingService自動(dòng)連接的類,以便記錄器消息顯示問題的原始來源.我試圖以某種方式更改服務(wù)
但不知道如何傳遞源類

 public class LoggingService<T> {

       protected static Logger logger = null;

       Class<T> sourceClass;

       public void construct(Class<T> sourceClass)
       {
           this.sourceClass = sourceClass;
           logger = LoggerFactory.getLogger(sourceClass);
       }

       public String debug(String debug_msg)
       {
           String uniqueMsgId = generateUniqueId();
           logger.debug(concatIdWithMsg(uniqueMsgId, debug_msg));
           return null;
       }
    }

解決方法:

我使用這種機(jī)制來注入記錄器.

創(chuàng)建此注釋.

/**
* Indicates InjectLogger of appropriate type to
* be supplied at runtime to the annotated field.
*
* The injected logger is an appropriate implementation
* of org.slf4j.Logger.
*/
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

@Retention(RUNTIME)
@Target(FIELD)
@Documented
public @interface InjectLogger {
}

現(xiàn)在讓我們定義一個(gè)實(shí)際上完成注入記錄器實(shí)現(xiàn)工作的類.

/**
 * Auto injects the underlying implementation of logger into the bean with field
 * having annotation <code>InjectLogger</code>.
 * 
 */
import java.lang.reflect.Field;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.util.ReflectionUtils;

import static org.springframework.util.ReflectionUtils.FieldCallback;

public class LoggerInjector implements BeanPostProcessor {

 public Object postProcessAfterInitialization(Object bean, String beanName)
   throws BeansException {
  return bean;
 }

 public Object postProcessBeforeInitialization(final Object bean,
   String beanName) throws BeansException {
  ReflectionUtils.doWithFields(bean.getClass(), new FieldCallback() {
   public void doWith(Field field) throws IllegalArgumentException,
     IllegalAccessException {
    // make the field accessible if defined private
    ReflectionUtils.makeAccessible(field);
    if (field.getAnnotation(InjectLogger.class) != null) {
     Logger log = LoggerFactory.getLogger(bean.getClass());
     field.set(bean, log);
    }
   }
  });
  return bean;
 }
}

使用它甚至更簡單.只需將上面創(chuàng)建的Logger批注添加到所需類的Log字段中即可.

import org.slf4j.Logger;

public class Demo {

 @InjectLogger
 private Logger log;

 public void doSomething() {
  log.info("message");
  log.error("Lets see how the error message looks...");
 }
}