官网
    http://log4mongo.org/display/PUB/Log4mongo+for+Java

保存主机信息，方法等
     http://my.oschina.net/chinaearl/blog/111552

只保存输出信息
 http://www.myexception.cn/program/650442.html

配置
log4j.rootLogger=INFO, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.logger.MongoDB=INFO,MongoDB
log4j.appender.MongoDB=org.log4mongo.MongoDbPatternLayoutAppender
log4j.appender.MongoDB.Threshold=INFO
log4j.appender.MongoDB.databaseName=mydb
log4j.appender.MongoDB.collectionName=optlog
log4j.appender.MongoDB.hostname=10.25.193.16
log4j.appender.MongoDB.port=9933
log4j.appender.MongoDB.layout=org.log4mongo.MongoDbPatternLayout

log4j.logger.MongoDB2=INFO,MongoDB2
log4j.appender.MongoDB2=org.log4mongo.MongoDbPatternLayoutAppender
log4j.appender.MongoDB2.Threshold=INFO
log4j.appender.MongoDB2.databaseName=mydb
log4j.appender.MongoDB2.collectionName=abclog
log4j.appender.MongoDB2.hostname=10.25.193.16
log4j.appender.MongoDB2.port=9933
log4j.appender.MongoDB2.layout=org.log4mongo.MongoDbPatternLayout

类
public static void main(String[] args) {
    Logger logger = Logger.getLogger("MongoDB");
    logger.info("{'provinceCode': null, 'channelSubCode': null,
'platFormCode': '002', 'optCode': null, 'startTimeLong': 1384599600000,
'processTime_sum': 10081,'count': 404, 'suc_count': 0,'suc_rate':
'0.00000'}");
 
    Logger logger2 = Logger.getLogger("MongoDB2");
    logger2.info("{'provinceCode':123}");
}