java官方日志jul,位于java.util.logging包下。
jul模块主要包含三个:Level、Formatter和Handler。
日志级别,由高到低有:OFF/SEVERE/WARNIN/INFO/CONFIG/FINE/FINERG/FINEST/ALL,
每个级别有自己的数值,在java.util.logging.Level类中源码如下:
public static final Level OFF = new Level("OFF",Integer.MAX_VALUE, defaultBundle);
public static final Level SEVERE = new Level("SEVERE",1000, defaultBundle);
public static final Level WARNING = new Level("WARNING", 900, defaultBundle);
public static final Level INFO = new Level("INFO", 800, defaultBundle);
public static final Level CONFIG = new Level("CONFIG", 700, defaultBundle);
public static final Level FINE = new Level("FINE", 500, defaultBundle);
public static final Level FINER = new Level("FINER", 400, defaultBundle);
public static final Level FINEST = new Level("FINEST", 300, defaultBundle);
public static final Level ALL = new Level("ALL", Integer.MIN_VALUE, defaultBundle);
可自定义日志级别,继承java.util.logging.Level类即可。
定义日志输出的格式,目前有SimpleFormatter和XMLFormatter两种格式,分别对应简单格式和xml格式。
可自定输出格式,继承抽象类java.util.logging.Formatter即可。
日志输出的目的,目前有
FileHandler:输出到文件,默认Level为INFO,Formatter为XMLFormatter;;
ConsoleHandler:输出到控制台,默认Level为INFO,流为System.err,Formatter为SimpleFormatter;
SocketHandler:输出到socket;
MemoryHandler:输出到内存;
可自定义日志级别,继承java.util.logging.Formatter类即可。
jul关键类是java.util.logging.Logger,通过此类定义logger,相同logger名称只有一个实例。
如:Logger logger = Logger.getLogger(“javaLog”);
java.util.logging包下的类图如下:
这里直接通过代码,介绍Logger的使用,详情请查看注释。
import java.util.logging.*;
public class JavaLogStudyMain {
public static void main(String[] args) throws Exception {
//简单格式的Formatter
SimpleFormatter sf = new SimpleFormatter();
//xml格式的formatter
XMLFormatter xf = new XMLFormatter();
//输出到文件的hander,指定日志输出级别为ALL
FileHandler fh = new FileHandler("jul_study.log");
fh.setLevel(Level.ALL);
fh.setFormatter(sf);
// fh.setFormatter(xf);
//输出到控制台的handler,指定日志输出级别为INFO
ConsoleHandler ch = new ConsoleHandler();
ch.setLevel(Level.INFO);
//获取logger实例,相同名的只能生成一个实例
Logger logger = Logger.getLogger("javaLog");
logger.addHandler(fh); //添加输出handler
logger.addHandler(ch); //添加输出handler
logger.setLevel(Level.ALL); //指定logger日志级别
//日志输出简写形式,有不同的级别,可带参数,其它类似
logger.log(Level.INFO, "this is a info, {0}", "p1");
logger.log(Level.WARNING, "this is a warn, {0} {1}", new Object[]{"p1", "p2"});
logger.log(Level.SEVERE, "this is a severe");
logger.log(Level.FINE, "this is a fine");
logger.log(Level.FINEST, "this is a finest");
logger.log(Level.CONFIG, "this is a config");
logger.log(Level.INFO, "this is a info", new Exception("my excep")); //带异常输出
//日志输出简写形式,有不同的级别
logger.severe("severe log");
logger.warning("warning log");
logger.info("info log");
logger.config("config log");
logger.fine("fine log");
logger.finer("finer log");
logger.finest("finest log");
}
}
这里通过继承Level、Handler、Formatter自定义Logger,日志存在文件中,且每个不同的loggerName存不同日志文件中。示例如下,解释请查看注释:
import org.apache.commons.lang.time.DateFormatUtils;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;
import java.util.logging.*;
public class SelfJavaLogMain {
//生成单例日志输出handler实例
private static SelfHandle sf = new SelfHandle();
/
* 根据class获取logger
* @param clazz
* @return
*/
public static Logger getLogger(Class clazz){
return getLogger(clazz.getSimpleName());
}
/
* 根据loggerName获取logger
* @param loggerName
* @return
*/
public static Logger getLogger(String loggerName){
Logger logger = Logger.getLogger(loggerName);
logger.addHandler(sf);
return logger;
}
/
* 自定义日志格式formatter
*/
public static class SelfFormater extends Formatter {
public static SelfFormater selfFormater = new SelfFormater();
@Override
public String format(LogRecord record) {
return String.format("[%s] %s %s.%s: %s\r\n", DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss"),
record.getLevel().getName(), record.getSourceClassName(), record.getSourceMethodName(), record.getMessage());
}
public static SelfFormater getInstance() {
return selfFormater;
}
}
/
* 自定义日志level
*/
public static class SelfLevel extends Level {
public static SelfLevel ERROR = new SelfLevel("ERROR", 910);
/
* @param name 自定义级别名称
* @param value 自定义级别的权重值
*/
protected SelfLevel(String name, int value) {
super(name, value);
}
}
/
* 自定义日志输出handler
*/
public static class SelfHandle extends Handler {
/
* 日志写入的位置
*
* @param record
*/
@Override
public void publish(LogRecord record) {
try {
//每一个不同的loggerName分别记在不同的日志文件中
File file = new File(String.format("%s_%s.log",record.getLoggerName(), DateFormatUtils.format(new Date(),"yyyy-MM-dd")));
if(!file.exists()){
file.createNewFile();
}
FileWriter fw = new FileWriter(file,true);
PrintWriter pw = new PrintWriter(fw);
String log = String.format("[%s] %s %s.%s: %s\r\n", DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss"),
record.getLevel().getName(), record.getSourceClassName(), record.getSourceMethodName(), record.getMessage());
pw.write(log);
pw.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
/
* 刷新缓存区,保存数据
*/
@Override
public void flush() {
}
/
* 关闭
*
* @throws SecurityException
*/
@Override
public void close() throws SecurityException {
}
}
public static void main(String[] args) throws Exception {
//获取自定义的logger
Logger logger = getLogger(SelfJavaLogMain.class);
logger.info("info log");
logger.severe("severe log");
//使用自定义的logger level
logger.log(SelfLevel.ERROR, "error log");
}
}
jre(java runtime environment, 即java运行环境)的默认日志配置为jre/lib/logging.properties,
其配置如下:
\############################################################
\# Default Logging Configuration File
\#
\# You can use a different file by specifying a filename
\# with the java.util.logging.config.file system property.
\# For example java -Djava.util.logging.config.file=myfile
\############################################################
\############################################################
\# Global properties
\############################################################
\# "handlers" specifies a comma separated list of log Handler
\# classes. These handlers will be installed during VM startup.
\# Note that these classes must be on the system classpath.
\# By default we only configure a ConsoleHandler, which will only
\# show messages at the INFO and above levels.
handlers= java.util.logging.ConsoleHandler
\# To also add the FileHandler, use the following line instead.
\#handlers= java.util.logging.FileHandler, java.util.logging.ConsoleHandler
\# Default global logging level.
\# This specifies which kinds of events are logged across
\# all loggers. For any given facility this global level
\# can be overriden by a facility specific level
\# Note that the ConsoleHandler also has a separate level
\# setting to limit messages printed to the console.
.level= INFO
\############################################################
\# Handler specific properties.
\# Describes specific configuration info for Handlers.
\############################################################
\# default file output is in user's home directory.
java.util.logging.FileHandler.pattern = %h/java%u.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 1
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
\# Limit the message that are printed on the console to INFO and above.
java.util.logging.ConsoleHandler.level = INFO
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
\# Example to customize the SimpleFormatter output format
\# to print one-line log message like this:
\# : []
\#
\# java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n
\############################################################
\# Facility specific properties.
\# Provides extra control for each logger.
\############################################################
\# For example, set the com.xyz.foo logger to only log SEVERE
\# messages:
com.xyz.foo.level = SEVERE