# Common log4j Configuration

Log4j configuration is commonly used. Two methods are generally used:. properties and. xml. The following two simple examples are provided:
1. log4j. Properties

### Set Org. level info, debug, warn, error, and output location a1, a2 # log4j.category.org. zblog = error, A1 log4j.category.org. zblog = info, A2 log4j. appender. a1 = org. apache. log4j. consoleappender ### set the output location A1 to leleappender (console) ## log4j. appender. a1.layout = org. apache. log4j. patternlayout ### set the output layout format patterlayout of A1. (you can flexibly specify the layout mode.) # log4j. appender. a1.layout. conversionpattern = % d {yyyy-mm-dd hh: mm: SS, SSS} [% C]-[% P] % m % N ### configure the log output format ## log4j. appender. a2 = org. apache. log4j. rollingfileappender ### set the output location A2 to the file (a new file is generated when the file size reaches the specified size) # log4j. appender. a2.file = E:/study/log4j/zhuwei.html ### File Location ## log4j. appender. a2.maxfilesize = 500kb ### file size # log4j. appender. a2.maxbackupindex = 1 log4j. appender. a2.layout = org. apache. log4j. htmllayout

HTML output

Ii. log4j. xml

<? XML version = "1.0" encoding = "gb2312"?> <! Doctype log4j: Configuration System "log4j. DTD "> <log4j: configuration xmlns: log4j =" http://jakarta.apache.org/log4j/ "> <appender name =" org. zblog. all "class =" org. apache. log4j. rollingfileappender "> <! -- Set the channel ID: Org. zblog. all and output mode: Org. apache. log4j. rollingfileappender --> <Param name = "file" value = "E:/study/log4j/All. output. log "/> <! -- Set the file parameter: log output file name --> <Param name = "APPEND" value = "false"/> <! -- Set whether to add new logs to the base of the original log when the service is restarted --> <Param name = "maxbackupindex" value = "10"/> <layout class = "org. apache. log4j. patternlayout "> <Param name =" conversionpattern "value =" % P (% C: % L)-% m % N "/> <! -- Set the output file project and format --> </layout> </appender> <appender name = "org. zblog. zcw "class =" org. apache. log4j. rollingfileappender "> <Param name =" file "value =" E:/study/log4j/zhuwei. output. log "/> <Param name =" APPEND "value =" true "/> <Param name =" maxfilesize "value =" 10240 "/> <! -- Set the file size --> <Param name = "maxbackupindex" value = "10"/> <layout class = "org. apache. log4j. patternlayout "> <Param name =" conversionpattern "value =" % P (% C: % L) -% m % N "/> </layout> </appender> <logger name =" zcw. log "> <! -- Set the domain name limit, that is, the zcw. log domain and the following logs are output to the corresponding channel below --> <level value = "debug"/> <! -- Set level --> <appender-ref = "org. zblog. zcw"/> <! -- Corresponds to the preceding channel id --> </logger> <root> <! -- Set the channel for receiving all outputs --> <appender-ref = "org. zblog. All"/> <! -- Corresponds to the preceding channel id --> </root> </log4j: configuration>

Iii. configuration file loading method:

Import Org. apache. log4j. logger; import Org. apache. log4j. propertyconfigurator; import Org. apache. log4j. XML. domconfigurator; public class log4japp {public static void main (string [] ARGs) {domconfigurator. configure ("E:/study/log4j/log4j. XML "); // load. XML file // propertyconfigurator. configure ("E:/study/log4j/log4j. properties "); // load. properties file logger log = logger. getlogger ("org. zblog. test "); log.info (" test ");}}

4. project use log4j
In a web application, you can load the configuration file in a separate servlet, and configure the servlet in Web. XML to load when the application starts. In a multi-person project, you can set an output channel for each person, so that each person can use his/her own domain name when building a logger, output debugging information to your own log file.

5. Common output formats #-X: Left alignment when X information is output; # % P: log information level # % d {}: log information generation time # % C: log information location (Class Name) # % m: generated log details # % N: Output log information line feed