一、前言

基于commons-logging源码包(1.0.3)，对其中日志经常使用的org.apache.commons.logging.LogFactory抽象日志工厂类的实现类org.apache.commons.logging.impl.LogFactoryImpl工厂实现类进行源码分析，可以查出具体org.apache.commons.logging.log日志接口实现任基于org.apache.commons.logging.impl.Jdk14Logger、org.apache.commons.logging.impl.Log4JLogger日志实现类。

二、源码说明

1.LogFactory抽象类接口

package org.apache.commons.logging;@b@@b@import java.io.BufferedReader;@b@import java.io.IOException;@b@import java.io.InputStream;@b@import java.io.InputStreamReader;@b@import java.io.UnsupportedEncodingException;@b@import java.lang.reflect.InvocationTargetException;@b@import java.lang.reflect.Method;@b@import java.security.AccessController;@b@import java.security.PrivilegedAction;@b@import java.util.Enumeration;@b@import java.util.Hashtable;@b@import java.util.Properties;@b@@b@public abstract class LogFactory@b@{@b@  public static final String FACTORY_PROPERTY = "org.apache.commons.logging.LogFactory";@b@  public static final String FACTORY_DEFAULT = "org.apache.commons.logging.impl.LogFactoryImpl";@b@  public static final String FACTORY_PROPERTIES = "commons-logging.properties";@b@  protected static final String SERVICE_ID = "META-INF/services/org.apache.commons.logging.LogFactory";@b@  protected static Hashtable factories = new Hashtable();@b@@b@  public abstract void release();@b@@b@  public static void releaseAll()@b@  {@b@    synchronized (factories) {@b@      Enumeration elements = factories.elements();@b@      while (elements.hasMoreElements()) {@b@        LogFactory element = (LogFactory)elements.nextElement();@b@        element.release();@b@      }@b@      factories.clear();@b@    }@b@  }@b@@b@  protected static ClassLoader getContextClassLoader()@b@    throws LogConfigurationException@b@  {@b@    ClassLoader classLoader = null;@b@    try@b@    {@b@      Method method = Thread.class.getMethod("getContextClassLoader", null);@b@      try@b@      {@b@        classLoader = (ClassLoader)method.invoke(Thread.currentThread(), null);@b@      } catch (IllegalAccessException e) {@b@        throw new LogConfigurationException("Unexpected IllegalAccessException", e);@b@      }@b@      catch (InvocationTargetException e)@b@      {@b@        if (e.getTargetException() instanceof SecurityException) {@b@          break label85:@b@        }@b@@b@        throw new LogConfigurationException("Unexpected InvocationTargetException", e.getTargetException());@b@      }@b@@b@      label85: label88: break label88:@b@    }@b@    catch (NoSuchMethodException e) {@b@      classLoader = LogFactory.class.getClassLoader();@b@    }@b@@b@    return classLoader;@b@  }@b@@b@  public static void release(ClassLoader classLoader)@b@  {@b@    synchronized (factories) {@b@      LogFactory factory = (LogFactory)factories.get(classLoader);@b@      if (factory != null) {@b@        factory.release();@b@        factories.remove(classLoader);@b@      }@b@    }@b@  }@b@@b@  public abstract String[] getAttributeNames();@b@@b@  public abstract void removeAttribute(String paramString);@b@@b@  public static LogFactory getFactory()@b@    throws LogConfigurationException@b@  {@b@    String factoryClass;@b@    ClassLoader contextClassLoader = (ClassLoader)AccessController.doPrivileged(new PrivilegedAction()@b@    {@b@      public Object run()@b@      {@b@        return LogFactory.getContextClassLoader();@b@      }@b@@b@    });@b@    LogFactory factory = getCachedFactory(contextClassLoader);@b@    if (factory != null) {@b@      return factory;@b@    }@b@@b@    Properties props = null;@b@    try {@b@      InputStream stream = getResourceAsStream(contextClassLoader, "commons-logging.properties");@b@@b@      if (stream != null) {@b@        props = new Properties();@b@        props.load(stream);@b@        stream.close();@b@      }@b@    }@b@    catch (IOException e)@b@    {@b@    }@b@    catch (SecurityException e) {@b@    }@b@    try {@b@      factoryClass = System.getProperty("org.apache.commons.logging.LogFactory");@b@      if (factoryClass != null) {@b@        factory = newFactory(factoryClass, contextClassLoader);@b@      }@b@@b@    }@b@    catch (SecurityException e)@b@    {@b@    }@b@@b@    if (factory == null) {@b@      try {@b@        InputStream is = getResourceAsStream(contextClassLoader, "META-INF/services/org.apache.commons.logging.LogFactory");@b@@b@        if (is != null)@b@        {@b@          BufferedReader rd;@b@          try@b@          {@b@            rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));@b@          } catch (UnsupportedEncodingException e) {@b@            rd = new BufferedReader(new InputStreamReader(is));@b@          }@b@@b@          String factoryClassName = rd.readLine();@b@          rd.close();@b@@b@          if ((factoryClassName != null) && (!("".equals(factoryClassName))))@b@          {@b@            factory = newFactory(factoryClassName, contextClassLoader);@b@          }@b@@b@        }@b@@b@      }@b@      catch (Exception ex)@b@      {@b@      }@b@@b@    }@b@@b@    if ((factory == null) && (props != null)) {@b@      factoryClass = props.getProperty("org.apache.commons.logging.LogFactory");@b@      if (factoryClass != null) {@b@        factory = newFactory(factoryClass, contextClassLoader);@b@      }@b@@b@    }@b@@b@    if (factory == null) {@b@      factory = newFactory("org.apache.commons.logging.impl.LogFactoryImpl", LogFactory.class.getClassLoader());@b@    }@b@@b@    if (factory != null)@b@    {@b@      cacheFactory(contextClassLoader, factory);@b@@b@      if (props != null) {@b@        Enumeration names = props.propertyNames();@b@        while (names.hasMoreElements()) {@b@          String name = (String)names.nextElement();@b@          String value = props.getProperty(name);@b@          factory.setAttribute(name, value);@b@        }@b@      }@b@    }@b@@b@    return factory;@b@  }@b@@b@  public abstract Object getAttribute(String paramString);@b@@b@  public abstract void setAttribute(String paramString, Object paramObject);@b@@b@  public abstract Log getInstance(Class paramClass)@b@    throws LogConfigurationException;@b@@b@  public static Log getLog(Class clazz)@b@    throws LogConfigurationException@b@  {@b@    return getFactory().getInstance(clazz);@b@  }@b@@b@  public abstract Log getInstance(String paramString)@b@    throws LogConfigurationException;@b@@b@  public static Log getLog(String name)@b@    throws LogConfigurationException@b@  {@b@    return getFactory().getInstance(name);@b@  }@b@@b@  private static LogFactory getCachedFactory(ClassLoader contextClassLoader)@b@  {@b@    LogFactory factory = null;@b@@b@    if (contextClassLoader != null)@b@      factory = (LogFactory)factories.get(contextClassLoader);@b@@b@    return factory;@b@  }@b@@b@  private static void cacheFactory(ClassLoader classLoader, LogFactory factory)@b@  {@b@    if ((classLoader != null) && (factory != null))@b@      factories.put(classLoader, factory);@b@  }@b@@b@  private static InputStream getResourceAsStream(ClassLoader loader, String name)@b@  {@b@    return ((InputStream)AccessController.doPrivileged(new PrivilegedAction(loader, name) { private final ClassLoader val$loader;@b@      private final String val$name;@b@@b@      public Object run() { if (this.val$loader != null)@b@          return this.val$loader.getResourceAsStream(this.val$name);@b@@b@        return ClassLoader.getSystemResourceAsStream(this.val$name);@b@      }@b@    }));@b@  }@b@@b@  protected static LogFactory newFactory(String factoryClass, ClassLoader classLoader)@b@    throws LogConfigurationException@b@  {@b@    Object result = AccessController.doPrivileged(new PrivilegedAction(classLoader, factoryClass) {@b@      private final ClassLoader val$classLoader;@b@      private final String val$factoryClass;@b@@b@      public Object run() { try { if (this.val$classLoader != null)@b@          {@b@            try@b@            {@b@              return ((LogFactory)this.val$classLoader.loadClass(this.val$factoryClass).newInstance());@b@            } catch (ClassNotFoundException ex) {@b@              if (this.val$classLoader == ((LogFactory.class$org$apache$commons$logging$LogFactory == null) ? (LogFactory.class$org$apache$commons$logging$LogFactory = LogFactory.class$("org.apache.commons.logging.LogFactory")) : LogFactory.class$org$apache$commons$logging$LogFactory).getClassLoader())@b@              {@b@                throw ex;@b@              }@b@            }@b@            catch (NoClassDefFoundError e) {@b@              if (this.val$classLoader == ((LogFactory.class$org$apache$commons$logging$LogFactory == null) ? (LogFactory.class$org$apache$commons$logging$LogFactory = LogFactory.class$("org.apache.commons.logging.LogFactory")) : LogFactory.class$org$apache$commons$logging$LogFactory).getClassLoader())@b@              {@b@                throw e;@b@              }@b@            }@b@            catch (ClassCastException e)@b@            {@b@              if (this.val$classLoader == ((LogFactory.class$org$apache$commons$logging$LogFactory == null) ? (LogFactory.class$org$apache$commons$logging$LogFactory = LogFactory.class$("org.apache.commons.logging.LogFactory")) : LogFactory.class$org$apache$commons$logging$LogFactory).getClassLoader())@b@              {@b@                throw e;@b@              }@b@@b@            }@b@@b@          }@b@@b@          return ((LogFactory)Class.forName(this.val$factoryClass).newInstance()); } catch (Exception e) {@b@        }@b@        return new LogConfigurationException(e);@b@      }@b@@b@    });@b@    if (result instanceof LogConfigurationException)@b@      throw ((LogConfigurationException)result);@b@@b@    return ((LogFactory)result);@b@  }@b@}

2.实现工厂LogFactoryImpl类

package org.apache.commons.logging.impl;@b@@b@import java.lang.reflect.Constructor;@b@import java.lang.reflect.Method;@b@import java.security.AccessController;@b@import java.security.PrivilegedAction;@b@import java.util.Enumeration;@b@import java.util.Hashtable;@b@import java.util.Vector;@b@import org.apache.commons.logging.Log;@b@import org.apache.commons.logging.LogConfigurationException;@b@import org.apache.commons.logging.LogFactory;@b@@b@public class LogFactoryImpl extends LogFactory@b@{@b@  public static final String LOG_PROPERTY = "org.apache.commons.logging.Log";@b@  protected static final String LOG_PROPERTY_OLD = "org.apache.commons.logging.log";@b@  protected Hashtable attributes = new Hashtable();@b@  protected Hashtable instances = new Hashtable();@b@  private String logClassName;@b@  protected Constructor logConstructor = null;@b@  protected Class[] logConstructorSignature = { String.class };@b@  protected Method logMethod = null;@b@  protected Class[] logMethodSignature = { LogFactory.class };@b@@b@  public void release()@b@  {@b@    this.instances.clear();@b@  }@b@@b@  protected boolean isJdk14Available()@b@  {@b@    try@b@    {@b@      loadClass("java.util.logging.Logger");@b@      loadClass("org.apache.commons.logging.impl.Jdk14Logger");@b@      return true; } catch (Throwable t) {@b@    }@b@    return false;@b@  }@b@@b@  protected boolean isLog4JAvailable()@b@  {@b@    try@b@    {@b@      loadClass("org.apache.log4j.Logger");@b@      loadClass("org.apache.commons.logging.impl.Log4JLogger");@b@      return true; } catch (Throwable t) {@b@    }@b@    return false;@b@  }@b@@b@  static ClassLoader access$000()@b@    throws LogConfigurationException@b@  {@b@    return LogFactory.getContextClassLoader();@b@  }@b@@b@  protected String getLogClassName()@b@  {@b@    if (this.logClassName != null) {@b@      return this.logClassName;@b@    }@b@@b@    this.logClassName = ((String)getAttribute("org.apache.commons.logging.Log"));@b@@b@    if (this.logClassName == null) {@b@      this.logClassName = ((String)getAttribute("org.apache.commons.logging.log"));@b@    }@b@@b@    if (this.logClassName == null)@b@      try {@b@        this.logClassName = System.getProperty("org.apache.commons.logging.Log");@b@      }@b@      catch (SecurityException e)@b@      {@b@      }@b@@b@    if (this.logClassName == null)@b@      try {@b@        this.logClassName = System.getProperty("org.apache.commons.logging.log");@b@      }@b@      catch (SecurityException e)@b@      {@b@      }@b@@b@    if ((this.logClassName == null) && (isLog4JAvailable())) {@b@      this.logClassName = "org.apache.commons.logging.impl.Log4JLogger";@b@    }@b@@b@    if ((this.logClassName == null) && (isJdk14Available())) {@b@      this.logClassName = "org.apache.commons.logging.impl.Jdk14Logger";@b@    }@b@@b@    if (this.logClassName == null) {@b@      this.logClassName = "org.apache.commons.logging.impl.SimpleLog";@b@    }@b@@b@    return this.logClassName;@b@  }@b@@b@  public String[] getAttributeNames()@b@  {@b@    Vector names = new Vector();@b@    Enumeration keys = this.attributes.keys();@b@    while (keys.hasMoreElements())@b@      names.addElement((String)keys.nextElement());@b@@b@    String[] results = new String[names.size()];@b@    for (int i = 0; i < results.length; ++i)@b@      results[i] = ((String)names.elementAt(i));@b@@b@    return results;@b@  }@b@@b@  public void removeAttribute(String name)@b@  {@b@    this.attributes.remove(name);@b@  }@b@@b@  protected Constructor getLogConstructor()@b@    throws LogConfigurationException@b@  {@b@    if (this.logConstructor != null) {@b@      return this.logConstructor;@b@    }@b@@b@    String logClassName = getLogClassName();@b@@b@    Class logClass = null;@b@    try {@b@      logClass = loadClass(logClassName);@b@      if (logClass == null) {@b@        throw new LogConfigurationException("No suitable Log implementation for " + logClassName);@b@      }@b@@b@      if (!(Log.class.isAssignableFrom(logClass)))@b@        throw new LogConfigurationException("Class " + logClassName + " does not implement Log");@b@    }@b@    catch (Throwable t)@b@    {@b@      throw new LogConfigurationException(t);@b@    }@b@@b@    try@b@    {@b@      this.logMethod = logClass.getMethod("setLogFactory", this.logMethodSignature);@b@    }@b@    catch (Throwable t) {@b@      this.logMethod = null;@b@    }@b@@b@    try@b@    {@b@      this.logConstructor = logClass.getConstructor(this.logConstructorSignature);@b@      return this.logConstructor;@b@    } catch (Throwable t) {@b@      throw new LogConfigurationException("No suitable Log constructor " + this.logConstructorSignature + " for " + logClassName, t);@b@    }@b@  }@b@@b@  private static Class loadClass(String name)@b@    throws ClassNotFoundException@b@  {@b@    Object result = AccessController.doPrivileged(new PrivilegedAction(name) {@b@      private final String val$name;@b@@b@      public Object run() { ClassLoader threadCL = LogFactoryImpl.access$000();@b@        if (threadCL != null);@b@        try {@b@          return threadCL.loadClass(this.val$name);@b@        }@b@        catch (ClassNotFoundException e)@b@        {@b@          try@b@          {@b@            return Class.forName(this.val$name); } catch (ClassNotFoundException e) { }@b@        }@b@        return e;@b@      }@b@@b@    });@b@    if (result instanceof Class)@b@      return ((Class)result);@b@@b@    throw ((ClassNotFoundException)result);@b@  }@b@@b@  public Object getAttribute(String name)@b@  {@b@    return this.attributes.get(name);@b@  }@b@@b@  public void setAttribute(String name, Object value)@b@  {@b@    if (value == null)@b@      this.attributes.remove(name);@b@    else@b@      this.attributes.put(name, value);@b@  }@b@@b@  public Log getInstance(Class clazz)@b@    throws LogConfigurationException@b@  {@b@    return getInstance(clazz.getName());@b@  }@b@@b@  public Log getInstance(String name)@b@    throws LogConfigurationException@b@  {@b@    Log instance = (Log)this.instances.get(name);@b@    if (instance == null) {@b@      instance = newInstance(name);@b@      this.instances.put(name, instance);@b@    }@b@    return instance;@b@  }@b@@b@  protected Log newInstance(String name)@b@    throws LogConfigurationException@b@  {@b@    Log instance = null;@b@    try {@b@      Object[] params = new Object[1];@b@      params[0] = name;@b@      instance = (Log)getLogConstructor().newInstance(params);@b@      if (this.logMethod != null) {@b@        params[0] = this;@b@        this.logMethod.invoke(instance, params);@b@      }@b@      return instance;@b@    } catch (Throwable t) {@b@      throw new LogConfigurationException(t);@b@    }@b@  }@b@}

3.接口log

package org.apache.commons.logging;@b@@b@public abstract interface Log@b@{@b@  public abstract boolean isDebugEnabled();@b@@b@  public abstract boolean isErrorEnabled();@b@@b@  public abstract boolean isFatalEnabled();@b@@b@  public abstract boolean isInfoEnabled();@b@@b@  public abstract boolean isTraceEnabled();@b@@b@  public abstract boolean isWarnEnabled();@b@@b@  public abstract void debug(Object paramObject);@b@@b@  public abstract void error(Object paramObject);@b@@b@  public abstract void fatal(Object paramObject);@b@@b@  public abstract void info(Object paramObject);@b@@b@  public abstract void trace(Object paramObject);@b@@b@  public abstract void warn(Object paramObject);@b@@b@  public abstract void debug(Object paramObject, Throwable paramThrowable);@b@@b@  public abstract void error(Object paramObject, Throwable paramThrowable);@b@@b@  public abstract void fatal(Object paramObject, Throwable paramThrowable);@b@@b@  public abstract void info(Object paramObject, Throwable paramThrowable);@b@@b@  public abstract void trace(Object paramObject, Throwable paramThrowable);@b@@b@  public abstract void warn(Object paramObject, Throwable paramThrowable);@b@}

4.Jdk14Logger日志接口实现类

package org.apache.commons.logging.impl;@b@@b@import java.util.logging.Level;@b@import java.util.logging.Logger;@b@import org.apache.commons.logging.Log;@b@@b@public final class Jdk14Logger@b@  implements Log@b@{@b@  protected Logger logger = null;@b@@b@  public boolean isDebugEnabled()@b@  {@b@    return this.logger.isLoggable(Level.FINE);@b@  }@b@@b@  public boolean isErrorEnabled()@b@  {@b@    return this.logger.isLoggable(Level.SEVERE);@b@  }@b@@b@  public boolean isFatalEnabled()@b@  {@b@    return this.logger.isLoggable(Level.SEVERE);@b@  }@b@@b@  public boolean isInfoEnabled()@b@  {@b@    return this.logger.isLoggable(Level.INFO);@b@  }@b@@b@  public boolean isTraceEnabled()@b@  {@b@    return this.logger.isLoggable(Level.FINEST);@b@  }@b@@b@  public boolean isWarnEnabled()@b@  {@b@    return this.logger.isLoggable(Level.WARNING);@b@  }@b@@b@  public void debug(Object message)@b@  {@b@    log(Level.FINE, String.valueOf(message), null);@b@  }@b@@b@  public void error(Object message)@b@  {@b@    log(Level.SEVERE, String.valueOf(message), null);@b@  }@b@@b@  public void fatal(Object message)@b@  {@b@    log(Level.SEVERE, String.valueOf(message), null);@b@  }@b@@b@  public void info(Object message)@b@  {@b@    log(Level.INFO, String.valueOf(message), null);@b@  }@b@@b@  public void trace(Object message)@b@  {@b@    log(Level.FINEST, String.valueOf(message), null);@b@  }@b@@b@  public void warn(Object message)@b@  {@b@    log(Level.WARNING, String.valueOf(message), null);@b@  }@b@@b@  public Jdk14Logger(String name)@b@  {@b@    this.logger = Logger.getLogger(name);@b@  }@b@@b@  public Logger getLogger()@b@  {@b@    return this.logger;@b@  }@b@@b@  public void debug(Object message, Throwable exception)@b@  {@b@    log(Level.FINE, String.valueOf(message), exception);@b@  }@b@@b@  public void error(Object message, Throwable exception)@b@  {@b@    log(Level.SEVERE, String.valueOf(message), exception);@b@  }@b@@b@  public void fatal(Object message, Throwable exception)@b@  {@b@    log(Level.SEVERE, String.valueOf(message), exception);@b@  }@b@@b@  public void info(Object message, Throwable exception)@b@  {@b@    log(Level.INFO, String.valueOf(message), exception);@b@  }@b@@b@  public void trace(Object message, Throwable exception)@b@  {@b@    log(Level.FINEST, String.valueOf(message), exception);@b@  }@b@@b@  public void warn(Object message, Throwable exception)@b@  {@b@    log(Level.WARNING, String.valueOf(message), exception);@b@  }@b@@b@  private void log(Level level, String msg, Throwable ex)@b@  {@b@    if (this.logger.isLoggable(level))@b@    {@b@      Throwable dummyException = new Throwable();@b@      StackTraceElement[] locations = dummyException.getStackTrace();@b@@b@      String cname = "unknown";@b@      String method = "unknown";@b@      if ((locations != null) && (locations.length > 2)) {@b@        StackTraceElement caller = locations[2];@b@        cname = caller.getClassName();@b@        method = caller.getMethodName();@b@      }@b@      if (ex == null)@b@        this.logger.logp(level, cname, method, msg);@b@      else@b@        this.logger.logp(level, cname, method, msg, ex);@b@    }@b@  }@b@}

5.Log4JLogger日志接口实现类

package org.apache.commons.logging.impl;@b@@b@import org.apache.commons.logging.Log;@b@import org.apache.log4j.Logger;@b@import org.apache.log4j.Priority;@b@@b@public final class Log4JLogger@b@  implements Log@b@{@b@  private static final String FQCN = Log4JLogger.class.getName();@b@  private Logger logger = null;@b@@b@  public Log4JLogger()@b@  {@b@  }@b@@b@  public boolean isDebugEnabled()@b@  {@b@    return this.logger.isDebugEnabled();@b@  }@b@@b@  public boolean isErrorEnabled()@b@  {@b@    return this.logger.isEnabledFor(Priority.ERROR);@b@  }@b@@b@  public boolean isFatalEnabled()@b@  {@b@    return this.logger.isEnabledFor(Priority.FATAL);@b@  }@b@@b@  public boolean isInfoEnabled()@b@  {@b@    return this.logger.isInfoEnabled();@b@  }@b@@b@  public boolean isTraceEnabled()@b@  {@b@    return this.logger.isDebugEnabled();@b@  }@b@@b@  public boolean isWarnEnabled()@b@  {@b@    return this.logger.isEnabledFor(Priority.WARN);@b@  }@b@@b@  public void debug(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.DEBUG, message, null);@b@  }@b@@b@  public void error(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.ERROR, message, null);@b@  }@b@@b@  public void fatal(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.FATAL, message, null);@b@  }@b@@b@  public void info(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.INFO, message, null);@b@  }@b@@b@  public void trace(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.DEBUG, message, null);@b@  }@b@@b@  public void warn(Object message)@b@  {@b@    this.logger.log(FQCN, Priority.WARN, message, null);@b@  }@b@@b@  public Log4JLogger(String name)@b@  {@b@    this.logger = Logger.getLogger(name);@b@  }@b@@b@  public Logger getLogger()@b@  {@b@    return this.logger;@b@  }@b@@b@  public Log4JLogger(Logger logger)@b@  {@b@    this.logger = logger;@b@  }@b@@b@  public void debug(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.DEBUG, message, t);@b@  }@b@@b@  public void error(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.ERROR, message, t);@b@  }@b@@b@  public void fatal(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.FATAL, message, t);@b@  }@b@@b@  public void info(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.INFO, message, t);@b@  }@b@@b@  public void trace(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.DEBUG, message, t);@b@  }@b@@b@  public void warn(Object message, Throwable t)@b@  {@b@    this.logger.log(FQCN, Priority.WARN, message, t);@b@  }@b@}