为了在小型Java桌面应用程序中使用日志记录,我试图深入了解某些方法的操作。我使用一个非常愚蠢的小型Java程序对其进行测试。
特别是,在测试LogManager.readConfiguration()方法的行为时,我发现了一些奇怪的东西。在所有测试中,LogManager均从JRE目录中lib / logging.properties中的属性文件中读取其配置。此时,此文件的内容如下:
handlers=java.util.logging.ConsoleHandler
myapp2.handlers=java.util.logging.ConsoleHandler
myapp2.MyApp2.handlers=java.util.logging.ConsoleHandler
.level=OFF
java.util.logging.ConsoleHandler.level=ALL
java.util.logging.ConsoleHandler.formatter=java.util.logging.SimpleFormatter
java.util.logging.SimpleFormatter.format=%4$s: %5$s [%1$tc]%n
myapp2.level=WARNING
myapp2.MyApp2.level=INFO
Java程序的代码为:
package myapp2;
import java.io.IOException;
import java.util.logging.LogManager;
import java.util.logging.Logger;
public class MyApp2 {
private static final Logger LOGGER = Logger.getLogger(MyApp2.class.getPackage().getName());
private static final Logger LOGGER1 = Logger.getLogger(MyApp2.class.getName());
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
LOGGER.severe("severe at MyApp2");
LOGGER.warning("warning at MyApp2");
LOGGER.info("info at MyApp2");
LOGGER1.severe("severe1 at MyApp2");
LOGGER1.warning("warning1 at MyApp2");
LOGGER1.info("info1 at MyApp2");
LOGGER1.setLevel(null);
LOGGER1.setUseParentHandlers(false);
LOGGER1.severe("severe2 at MyApp2");
LOGGER1.warning("warning2 at MyApp2");
LOGGER1.info("info2 at MyApp2");
try {
LogManager.getLogManager().readConfiguration();
} catch (IOException ex) {
System.out.println("I/O Exception found");
} catch (SecurityException ex) {
System.out.println("Error SecurityException found");
}
LOGGER.severe("severe3 at MyApp2");
LOGGER1.severe("severe4 at MyApp2");
}
}
如果我们在没有围绕readConfiguration()的try-catch的情况下执行它,则将按预期工作,并且输出如下:
SEVERE: severe at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe2 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
WARNING: warning2 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe3 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe3 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
SEVERE: severe4 at MyApp2 [dc. maig 08 14:45:38 CEST 2013]
但是,如果我们使用try-catch执行,则输出为:
SEVERE: severe at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
INFO: info1 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe2 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
WARNING: warning2 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
SEVERE: severe3 at MyApp2 [dc. maig 08 14:46:51 CEST 2013]
读取readConfiguration()方法的API后,应该重新初始化日志记录属性,并从先前命名的文件中重新读取日志记录配置。如果是的话,为什么feature3仅显示一次(由于程序中存在两个LOGGER和转发行为,我预计将显示两次)而严重4丢失(我希望显示一次)?有人可以帮我理解这个吗?
参考方案
我在readConfiguration方法中遇到了很多错误。它不是您期望的那样。我创建了一个小单元测试来说明这一点:
package com.demo;
import java.io.IOException;
import java.io.InputStream;
import java.util.logging.LogManager;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author dhubau
*/
public class LogTest {
private static final Logger logger = LoggerFactory.getLogger(LogTest.class.getCanonicalName());
@Test
public void testLogs() throws IOException {
logger.trace("BEFORE");
logger.debug("BEFORE");
logger.info("BEFORE");
logger.warn("BEFORE");
logger.error("BEFORE");
InputStream is = LogTest.class.getResourceAsStream("/logging.properties");
LogManager.getLogManager().readConfiguration(is);
logger.trace("AFTER");
logger.debug("AFTER");
logger.info("AFTER");
logger.warn("AFTER");
logger.error("AFTER");
}
}
启动单元测试时,将读取默认的logging.properties(将所有信息默认为INFO日志记录)。我记录每个级别一次,然后读取自己的logging.properties文件:
# Specify the handlers to create in the root logger
handlers = java.util.logging.ConsoleHandler
# Set the default logging level for the root logger
.level = INFO
# Do not use the root handlers
com.demo.useParentHandlers = false
# DEMO log handlers
com.demo.handlers = java.util.logging.ConsoleHandler
# DEMO log level
com.demo.level = ALL
# Set the default logging level for new ConsoleHandler instances
java.util.logging.ConsoleHandler.level = ALL
之后,我得到以下输出:
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
INFO: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
WARNING: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
SEVERE: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
INFO: AFTER
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
WARNING: AFTER
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
SEVERE: AFTER
因此,您看到com.demo程序包未记录TRACE或DEBUG级别。当我将以下参数传递给单元测试时:
java.util.logging.config.file = C:\ TEMP \ logging.properties
它给了我以下输出:
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
FINEST: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
FINE: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
INFO: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
WARNING: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
SEVERE: BEFORE
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
INFO: AFTER
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
WARNING: AFTER
May 24, 2013 11:27:29 AM com.demo.LogTest testLogs
SEVERE: AFTER
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