java基础-log4j关键接口和类

我们以1.X版本为例

// 使用非显式配置文件

 TTCCLayout layout = new TTCCLayout();

FileAppender appender = new FileAppender(layout,"e://testxxx.log");

BasicConfigurator.configure(appender);

Logger logger = Logger.getLogger(TestLog.class.getName());

logger.debug("sss");

 

// 使用显式配置文件

BasicConfigurator.configure();

Logger logger = Logger.getLogger(TestLog.class.getName());

logger.info("abcdefg");

 

log4j.properties

log4j.rootLogger=debug,console log4j.appender.logfile.encoding=UTF-8 log4j.appender.console=org.apache.log4j.ConsoleAppender log4j.appender.console.layout=org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=%d{yyy-MM-dd HH:mm:ss } %L %-5p %c - %m%n log4j.logger.org.apache.log4j=info,boss_service_logfile log4j.appender.boss_service_logfile=org.apache.log4j.RollingFileAppender log4j.appender.boss_service_logfile.File=e:/TestLog.log log4j.appender.boss_service_logfile.MaxFileSize=10000kb log4j.appender.boss_service_logfile.MaxBackupIndex=10 log4j.appender.boss_service_logfile.layout=org.apache.log4j.PatternLayout log4j.appender.boss_service_logfile.layout.ConversionPattern=%d{yyy-MM-dd HH:mm:ss} %-5p - %m%n

 

 

关键接口和类
public class PatternLayout extends Layout { 我们常用到这个进行模式匹配日志的布局或者说日志的样式
public class TTCCLayout extends DateLayout {
abstract public class DateLayout extends Layout {
public abstract class Layout implements OptionHandler {  日志布局
public interface OptionHandler {

public class FileAppender extends WriterAppender { 我们常用到的文件输出
public class ConsoleAppender extends WriterAppender {  我们常用到的控制台输出
public class WriterAppender extends AppenderSkeleton {
public abstract class AppenderSkeleton implements Appender, OptionHandler {
public interface Appender {  日志输出

public class AppenderAttachableImpl implements AppenderAttachable {

public class BasicConfigurator { 日志配置的基础包装类

public class Logger extends Category {  日志对象
public class Category implements AppenderAttachable {  真正的日志执行类
      protected void forcedLog(String fqcn, Priority level, Object message, Throwable t) {
         callAppenders(new LoggingEvent(fqcn, this, level, message, t));
     }

     //  该方法会把logger以及所属层级的日志对象，全部遍历一遍，然后在把每个日志对象的输出全部遍历一遍。
    public void callAppenders(LoggingEvent event) {
        int writes = 0;
        for (Category c = this; c != null; c = c.parent) {
            // Protected against simultaneous call to addAppender,
            // removeAppender,...
            synchronized (c) {
                if (c.aai != null) {
                    writes += c.aai.appendLoopOnAppenders(event);
                }
                if (!c.additive) {
                    break;
                }
            }
        }

        if (writes == 0) {
            repository.emitNoAppenderWarning(this);
        }
      }
  }
｝
public class AppenderAttachableImpl implements AppenderAttachable {
public int appendLoopOnAppenders(LoggingEvent event) {
    int size = 0;
    Appender appender;

    if(appenderList != null) {
      size = appenderList.size();
      for(int i = 0; i < size; i++) {
          appender = (Appender) appenderList.elementAt(i);
          appender.doAppend(event); // 增加多个日志对象的输出
      }
    }   
    return size;
  }
｝
public interface AppenderAttachable { 附加输出到对象

public class LogManager { 主要起到初始化配置文件、初始化日志选择器的作用

public class Hierarchy implements LoggerRepository, RendererSupport {  关键类
...
This class is specialized in retrieving loggers by name and also maintaining the logger hierarchy.
翻译：这个类是专门用来按名字检索日志对象和维持日志对象的层级
         public Logger getLogger(String name, LoggerFactory factory) {
        CategoryKey key = new CategoryKey(name);
        Logger logger;

        synchronized (ht) {
            Object o = ht.get(key);
            if (o == null) {
                logger = factory.makeNewLoggerInstance(name);  生成新的logger实例
                logger.setHierarchy(this);
                ht.put(key, logger);
                updateParents(logger);
                return logger;
            } else if (o instanceof Logger) {
                return (Logger) o;
            } else if (o instanceof ProvisionNode) {
                // System.out.println("("+name+") ht.get(this) returned ProvisionNode");
                logger = factory.makeNewLoggerInstance(name);
                logger.setHierarchy(this);
                ht.put(key, logger);
                updateChildren((ProvisionNode) o, logger);
                updateParents(logger);
                return logger;
            } else {
                // It should be impossible to arrive here
                return null; // but let's keep the compiler happy.
            }
        }
    }
...
｝
public interface LoggerRepository {
public interface RendererSupport {
public class DefaultRepositorySelector implements RepositorySelector { 默认的仓库选择器
public interface RepositorySelector {  仓库选择器

public class LoggingEvent implements java.io.Serializable {

public class PropertyConfigurator implements Configurator { 属性文件解析类
public class DOMConfigurator implements Configurator  xml文件解析类
public interface Configurator { 配置接口

public class Level extends Priority implements Serializable { 日志层级
public class Priority {

class DefaultCategoryFactory implements LoggerFactory {  日志对象工厂实现类
public interface LoggerFactory { 日志对象工厂接口

 

总体的印象 感觉log4j1.x版本的代码，几个抽象类和接口的设计很清晰，但代码的可读性不好，作者也不进行代码排版很混乱。