commons-logging 分析之: org.apache.commons.logging.impl.SimpleLog

傷城~ 2022-05-22 07:46 265阅读 0赞

*  分析info 日志
 *  SimpleLog初始化
    
     *  SimpleLog静态初始化
     *  SimpleLog 构造初始化
        
         *  获取属性
     *  SimpleLog 属性总结
 *  日志打印分析
    
     *  是否启用日志级别 isLevelEnabled
     *  打印日志
        
         *  打印
 *  控制台输出

# 分析info 日志 #

public class Main {
        public static void main(String[] args) {
            Log logger = LogFactory.getLog(Main.class);
            //**重点**
            logger.info("message");
        }
    }

# SimpleLog初始化 #

## SimpleLog静态初始化 ##

**触发初始化的地方:**  
//org.apache.commons.logging.impl.LogFactoryImpl::createLogFromClass  
c = Class.forName(logAdapterClassName, true, currentCL);

// Initialize class attributes.
        // Load properties file, if found.
        // Override with system properties.
        static {
            // Add props from the resource simplelog.properties
            // 从simplelog.properties 载入属性到 simpleLogProps 中
            InputStream in = getResourceAsStream("simplelog.properties");
            if(null != in) {
                try {
                    simpleLogProps.load(in);
                    in.close();
                } catch(java.io.IOException e) {
                    // ignored
                }
            }
            // static protected final String systemPrefix = "org.apache.commons.logging.simplelog.";
            // 是否显示日志：org.apache.commons.logging.simplelog.showlogname,  默认值：false
            showLogName = getBooleanProperty( systemPrefix + "showlogname", showLogName);
            // org.apache.commons.logging.simplelog.showShortLogname 是否显示短日志名称  默认值：true
            showShortName = getBooleanProperty( systemPrefix + "showShortLogname", showShortName);
            // org.apache.commons.logging.simplelog.showdatetime 是否显示时间 默认值：false 
            showDateTime = getBooleanProperty( systemPrefix + "showdatetime", showDateTime);
    
            if(showDateTime) {
            //static protected final String DEFAULT_DATE_TIME_FORMAT = "yyyy/MM/dd HH:mm:ss:SSS zzz";
            //static protected String dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
                //org.apache.commons.logging.simplelog.dateTimeFormat 时间格式化， 默认值： yyyy/MM/dd HH:mm:ss:SSS zzz
                dateTimeFormat = getStringProperty(systemPrefix + "dateTimeFormat",
                                                   dateTimeFormat);
                try {
                    dateFormatter = new SimpleDateFormat(dateTimeFormat);
                } catch(IllegalArgumentException e) {
                    // If the format pattern is invalid - use the default format
                    dateTimeFormat = DEFAULT_DATE_TIME_FORMAT;
                    dateFormatter = new SimpleDateFormat(dateTimeFormat);
                }
            }
        }

## SimpleLog 构造初始化 ##

public SimpleLog(String name) {
    
            logName = name;
    
            // Set initial log level
            // Used to be: set default log level to ERROR
            // IMHO it should be lower, but at least info ( costin ).
            //设置默认级别为 info 
            setLevel(SimpleLog.LOG_LEVEL_INFO);
    // static protected final String systemPrefix = "org.apache.commons.logging.simplelog.";
            // Set log level from properties
            //org.apache.commons.logging.simplelog.log.com.aya.Main
            String lvl = getStringProperty(systemPrefix + "log." + logName);
            int i = String.valueOf(name).lastIndexOf(".");
            // 遍历用户包：找到对应的日志级别
            //org.apache.commons.logging.simplelog.log.com.aya
            //org.apache.commons.logging.simplelog.log.com
            while(null == lvl && i > -1) {
                name = name.substring(0,i);
                lvl = getStringProperty(systemPrefix + "log." + name);
                i = String.valueOf(name).lastIndexOf(".");
            }
            // org.apache.commons.logging.simplelog.defaultlog 用户配置的默认级别
            if(null == lvl) {
                lvl =  getStringProperty(systemPrefix + "defaultlog");
            }
    
            if("all".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_ALL);
            } else if("trace".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_TRACE);
            } else if("debug".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_DEBUG);
            } else if("info".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_INFO);
            } else if("warn".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_WARN);
            } else if("error".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_ERROR);
            } else if("fatal".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_FATAL);
            } else if("off".equalsIgnoreCase(lvl)) {
                setLevel(SimpleLog.LOG_LEVEL_OFF);
            }
    
        }

### 获取属性 ###

1.  从系统环境变量中获取，不为null就返回
2.  从simpleLogProps 中获取（从simplelog.properties 载入的）

private static String getStringProperty(String name) {
            String prop = null;
            try {
    
                prop = System.getProperty(name);
            } catch (SecurityException e) {
                ; // Ignore
            }
            return (prop == null) ? simpleLogProps.getProperty(name) : prop;
        }

## SimpleLog 属性总结 ##

复制配置: [https://blog.csdn.net/gxmark/article/details/7338253][https_blog.csdn.net_gxmark_article_details_7338253]  
新建配置文件：simplelog.properties  
`org.apache.commons.logging.simplelog.defaultlog=trace org.apache.commons.logging.simplelog.log.XXXXXX=debug org.apache.commons.logging.simplelog.showlogname=true org.apache.commons.logging.simplelog.showShortLogname=true org.apache.commons.logging.simplelog.showdatetime=true org.apache.commons.logging.simplelog.dateTimeFormat=yyyy-MM-dd hh:mm:ss`

# 日志打印分析 #

public final void info(Object message) {
    
            if (isLevelEnabled(SimpleLog.LOG_LEVEL_INFO)) {
                log(SimpleLog.LOG_LEVEL_INFO,message,null);
            }
        }

## 是否启用日志级别 isLevelEnabled ##

/** * Is the given log level currently enabled? * * @param logLevel is this level enabled? */
        protected boolean isLevelEnabled(int logLevel) {
            // log level are numerically ordered so can use simple numeric
            // comparison
            // 日志级别是否大于等于当前日志级别
            return (logLevel >= currentLogLevel);
        }

## 打印日志 ##

*  拼接日志内容  
    
    
     *  showDateTime（时间）
     *  type（日志级别）
     *  showShortName（用户类的简单名称）
     *  t (异常信息)
 *  打印

protected void log(int type, Object message, Throwable t) {
            // Use a string buffer for better performance
            StringBuffer buf = new StringBuffer();
    
            // Append date-time if so configured
            if(showDateTime) {
                Date now = new Date();
                String dateText;
                synchronized(dateFormatter) {
                    dateText = dateFormatter.format(now);
                }
                buf.append(dateText);
                buf.append(" ");
            }
    
            // Append a readable representation of the log level
            switch(type) {
                case SimpleLog.LOG_LEVEL_TRACE: buf.append("[TRACE] "); break;
                case SimpleLog.LOG_LEVEL_DEBUG: buf.append("[DEBUG] "); break;
                case SimpleLog.LOG_LEVEL_INFO:  buf.append("[INFO] ");  break;
                case SimpleLog.LOG_LEVEL_WARN:  buf.append("[WARN] ");  break;
                case SimpleLog.LOG_LEVEL_ERROR: buf.append("[ERROR] "); break;
                case SimpleLog.LOG_LEVEL_FATAL: buf.append("[FATAL] "); break;
            }
    
            // Append the name of the log instance if so configured
            if( showShortName) {
                if( shortLogName==null ) {
                    // Cut all but the last component of the name for both styles
                    shortLogName = logName.substring(logName.lastIndexOf(".") + 1);
                    shortLogName =
                        shortLogName.substring(shortLogName.lastIndexOf("/") + 1);
                }
                buf.append(String.valueOf(shortLogName)).append(" - ");
            } else if(showLogName) {
                buf.append(String.valueOf(logName)).append(" - ");
            }
    
            // Append the message
            buf.append(String.valueOf(message));
    
            // Append stack trace if not null
            if(t != null) {
                buf.append(" <");
                buf.append(t.toString());
                buf.append(">");
    
                java.io.StringWriter sw= new java.io.StringWriter(1024);
                java.io.PrintWriter pw= new java.io.PrintWriter(sw);
                t.printStackTrace(pw);
                pw.close();
                buf.append(sw.toString());
            }
    
            // Print to the appropriate destination
            write(buf);
    
        }

### 打印 ###

protected void write(StringBuffer buffer) {
        // 系统错误输出
            System.err.println(buffer.toString());
    
        }

# 控制台输出 #

2018-06-19 04:37:01 [INFO] Main - message

[https_blog.csdn.net_gxmark_article_details_7338253]: https://blog.csdn.net/gxmark/article/details/7338253