===============>>#1 票数:41 已采纳
使用slf4j无法做到这slf4j 。
我想,缺少这个功能的原因是,几乎不可能为slf4j构建一个Level类型,它可以有效地映射到Facade后面所有可能的日志记录实现中使用的Level (或等效)类型。 或者,设计人员认为您的用例太不寻常 ,无法证明支持它的开销。
关于@ ripper234的用例 (单元测试),我认为实用的解决方案是修改单元测试,以便在运行单元测试时强硬了解slf4j外观背后的日志系统。
===============>>#2 票数:25
Richard Fearn有正确的想法,所以我根据他的骨架代码编写了完整的类。 希望足够短,可以在这里发布。 复制和粘贴享受。 我应该添加一些神奇的咒语:“此代码发布到公共领域”
import org.slf4j.Logger;
public class LogLevel {
/**
* Allowed levels, as an enum. Import using "import [package].LogLevel.Level"
* Every logging implementation has something like this except SLF4J.
*/
public static enum Level {
TRACE, DEBUG, INFO, WARN, ERROR
}
/**
* This class cannot be instantiated, why would you want to?
*/
private LogLevel() {
// Unreachable
}
/**
* Log at the specified level. If the "logger" is null, nothing is logged.
* If the "level" is null, nothing is logged. If the "txt" is null,
* behaviour depends on the SLF4J implementation.
*/
public static void log(Logger logger, Level level, String txt) {
if (logger != null && level != null) {
switch (level) {
case TRACE:
logger.trace(txt);
break;
case DEBUG:
logger.debug(txt);
break;
case INFO:
logger.info(txt);
break;
case WARN:
logger.warn(txt);
break;
case ERROR:
logger.error(txt);
break;
}
}
}
/**
* Log at the specified level. If the "logger" is null, nothing is logged.
* If the "level" is null, nothing is logged. If the "format" or the "argArray"
* are null, behaviour depends on the SLF4J-backing implementation.
*/
public static void log(Logger logger, Level level, String format, Object[] argArray) {
if (logger != null && level != null) {
switch (level) {
case TRACE:
logger.trace(format, argArray);
break;
case DEBUG:
logger.debug(format, argArray);
break;
case INFO:
logger.info(format, argArray);
break;
case WARN:
logger.warn(format, argArray);
break;
case ERROR:
logger.error(format, argArray);
break;
}
}
}
/**
* Log at the specified level, with a Throwable on top. If the "logger" is null,
* nothing is logged. If the "level" is null, nothing is logged. If the "format" or
* the "argArray" or the "throwable" are null, behaviour depends on the SLF4J-backing
* implementation.
*/
public static void log(Logger logger, Level level, String txt, Throwable throwable) {
if (logger != null && level != null) {
switch (level) {
case TRACE:
logger.trace(txt, throwable);
break;
case DEBUG:
logger.debug(txt, throwable);
break;
case INFO:
logger.info(txt, throwable);
break;
case WARN:
logger.warn(txt, throwable);
break;
case ERROR:
logger.error(txt, throwable);
break;
}
}
}
/**
* Check whether a SLF4J logger is enabled for a certain loglevel.
* If the "logger" or the "level" is null, false is returned.
*/
public static boolean isEnabledFor(Logger logger, Level level) {
boolean res = false;
if (logger != null && level != null) {
switch (level) {
case TRACE:
res = logger.isTraceEnabled();
break;
case DEBUG:
res = logger.isDebugEnabled();
break;
case INFO:
res = logger.isInfoEnabled();
break;
case WARN:
res = logger.isWarnEnabled();
break;
case ERROR:
res = logger.isErrorEnabled();
break;
}
}
return res;
}
}
===============>>#3 票数:12
尝试切换到Logback并使用
ch.qos.logback.classic.Logger rootLogger = (ch.qos.logback.classic.Logger)LoggerFactory.getLogger(ch.qos.logback.classic.Logger.ROOT_LOGGER_NAME);
rootLogger.setLevel(Level.toLevel("info"));
我相信这将是对Logback的唯一调用,其余代码将保持不变。 Logback使用SLF4J,迁移将毫不费力,只需要更改xml配置文件。
记得在完成后重新设置日志级别。
===============>>#4 票数:11
您可以使用Java 8 lambdas实现此功能。
import java.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.event.Level;
public class LevelLogger {
private static final Logger LOGGER = LoggerFactory.getLogger(LevelLogger.class);
private static final Map map;
static {
map = new HashMap<>();
map.put(Level.TRACE, (o) -> LOGGER.trace(o));
map.put(Level.DEBUG, (o) -> LOGGER.debug(o));
map.put(Level.INFO, (o) -> LOGGER.info(o));
map.put(Level.WARN, (o) -> LOGGER.warn(o));
map.put(Level.ERROR, (o) -> LOGGER.error(o));
}
public static void log(Level level, String s) {
map.get(level).log(s);
}
@FunctionalInterface
private interface LoggingFunction {
public void log(String arg);
}
}
===============>>#5 票数:6
这可以使用enum和辅助方法完成:
enum LogLevel {
TRACE,
DEBUG,
INFO,
WARN,
ERROR,
}
public static void log(Logger logger, LogLevel level, String format, Object[] argArray) {
switch (level) {
case TRACE:
logger.trace(format, argArray);
break;
case DEBUG:
logger.debug(format, argArray);
break;
case INFO:
logger.info(format, argArray);
break;
case WARN:
logger.warn(format, argArray);
break;
case ERROR:
logger.error(format, argArray);
break;
}
}
// example usage:
private static final Logger logger = ...
final LogLevel level = ...
log(logger, level, "Something bad happened", ...);
您可以添加其他log变量,例如,如果您想要SLF4J的1参数或2参数warn / error /等的通用等价物。 方法。
===============>>#6 票数:5
任何想要完全解决此问题的SLF4J兼容解决方案的人都可以查看Lidalia SLF4J扩展 - 它位于Maven Central上。
===============>>#7 票数:2
我只是需要这样的东西并提出:
@RequiredArgsConstructor //lombok annotation
public enum LogLevel{
TRACE(l -> l::trace),
INFO (l -> l::info),
WARN (l -> l::warn),
ERROR(l -> l::error);
private final Function> function;
public void log(Logger logger, String message) {
function.apply(logger).accept(message);
}
}
用法:
LogLevel level = LogLevel.TRACE;
level.log(logger, "message");
Logger在调用期间传递,因此类信息应该没问题,并且它与@ Slf4j lombok注释很好地配合。
===============>>#8 票数:1
无法在开箱即用的sjf4j 1.x指定日志级别。 但是slf4j 2.0有希望解决这个问题 。 在2.0中它可能看起来像这样:
// POTENTIAL 2.0 SOLUTION
import org.slf4j.helpers.Util;
import static org.slf4j.spi.LocationAwareLogger.*;
// does not work with slf4j 1.x
Util.log(logger, DEBUG_INT, "hello world!");
同时,对于slf4j 1.x,您可以使用此解决方法:
将此类复制到您的类路径中:
import org.slf4j.Logger;
import java.util.function.Function;
public enum LogLevel {
TRACE(l -> l::trace, Logger::isTraceEnabled),
DEBUG(l -> l::debug, Logger::isDebugEnabled),
INFO(l -> l::info, Logger::isInfoEnabled),
WARN(l -> l::warn, Logger::isWarnEnabled),
ERROR(l -> l::error, Logger::isErrorEnabled);
interface LogMethod {
void log(String format, Object... arguments);
}
private final Function logMethod;
private final Function isEnabledMethod;
LogLevel(Function logMethod, Function isEnabledMethod) {
this.logMethod = logMethod;
this.isEnabledMethod = isEnabledMethod;
}
public LogMethod prepare(Logger logger) {
return logMethod.apply(logger);
}
public boolean isEnabled(Logger logger) {
return isEnabledMethod.apply(logger);
}
}
然后你可以像这样使用它:
Logger logger = LoggerFactory.getLogger(Application.class);
LogLevel level = LogLevel.ERROR;
level.prepare(logger).log("It works!"); // just message, without parameter
level.prepare(logger).log("Hello {}!", "world"); // with slf4j's parameter replacing
try {
throw new RuntimeException("Oops");
} catch (Throwable t) {
level.prepare(logger).log("Exception", t);
}
if (level.isEnabled(logger)) {
level.prepare(logger).log("logging is enabled");
}
这将输出如下日志:
[main] ERROR Application - It works!
[main] ERROR Application - Hello world!
[main] ERROR Application - Exception
java.lang.RuntimeException: Oops
at Application.main(Application.java:14)
[main] ERROR Application - logging is enabled
这值得么?
Pro保留源代码位置 (类名,方法名,行号将指向您的代码)
Pro您可以轻松地将变量 ,参数和返回类型定义为LogLevel
Pro您的业务代码保持简短易读,不需要其他依赖项 。
作为最小示例的源代码托管在GitHub上 。
===============>>#9 票数:0
我刚刚遇到了类似的需求。 在我的例子中,slf4j配置了java日志适配器(jdk14)。 使用以下代码片段,我设法在运行时更改调试级别:
Logger logger = LoggerFactory.getLogger("testing");
java.util.logging.Logger julLogger = java.util.logging.Logger.getLogger("testing");
julLogger.setLevel(java.util.logging.Level.FINE);
logger.debug("hello world");
===============>>#10 票数:0
基于massimo virgilio的答案,我还设法使用内省来使用slf4j-log4j。 HTH。
Logger LOG = LoggerFactory.getLogger(MyOwnClass.class);
org.apache.logging.slf4j.Log4jLogger LOGGER = (org.apache.logging.slf4j.Log4jLogger) LOG;
try {
Class loggerIntrospected = LOGGER.getClass();
Field fields[] = loggerIntrospected.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
String fieldName = fields[i].getName();
if (fieldName.equals("logger")) {
fields[i].setAccessible(true);
org.apache.logging.log4j.core.Logger loggerImpl = (org.apache.logging.log4j.core.Logger) fields[i].get(LOGGER);
loggerImpl.setLevel(Level.DEBUG);
}
}
} catch (Exception e) {
System.out.println("ERROR :" + e.getMessage());
}
===============>>#11 票数:0
这是一个lambda解决方案,不像@Paul Croarkin那样用户友好(水平有效地传递了两次)。 但我认为(a)用户应该通过Logger; (b)AFAIU原始问题并不是要求应用程序中的任何地方使用方便的方法,只是在图书馆内几乎没有使用的情况。
package test.lambda;
import java.util.function.*;
import org.slf4j.*;
public class LoggerLambda {
private static final Logger LOG = LoggerFactory.getLogger(LoggerLambda.class);
private LoggerLambda() {}
public static void log(BiConsumer super String, ? super Object[]> logFunc, Supplier logEnabledPredicate,
String format, Object... args) {
if (logEnabledPredicate.get()) {
logFunc.accept(format, args);
}
}
public static void main(String[] args) {
int a = 1, b = 2, c = 3;
Throwable e = new Exception("something went wrong", new IllegalArgumentException());
log(LOG::info, LOG::isInfoEnabled, "a = {}, b = {}, c = {}", a, b, c);
// warn(String, Object...) instead of warn(String, Throwable), but prints stacktrace nevertheless
log(LOG::warn, LOG::isWarnEnabled, "error doing something: {}", e, e);
}
}
由于slf4j 允许在varargs参数中使用Throwable(其堆栈跟踪应该被记录) ,我认为不需要为其他使用者重载log助手方法(String, Object[]) 。
===============>>#12 票数:0
我能够通过首先请求SLF4J Logger实例然后在绑定上设置级别来为JDK14绑定执行此操作 - 您可以尝试使用Log4J绑定。
private void setLevel(Class loggerClass, java.util.logging.Level level) {
org.slf4j.LoggerFactory.getLogger(loggerClass);
java.util.logging.Logger.getLogger(loggerClass.getName()).setLevel(level);
}
===============>>#13 票数:0
我使用的方法是导入ch.qos.logback模块,然后将slf4j Logger实例类型转换为ch.qos.logback.classic.Logger。 此实例包含setLevel()方法。
import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.Logger;
Logger levelSet = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
// Now you can set the desired logging-level
levelSet.setLevel( Level.OFF );
要找出可能的日志级别,您可以展开ch.qos.logback类以查看Level的所有可能值:
prompt$ javap -cp logback-classic-1.2.3.jar ch.qos.logback.classic.Level
结果如下:
{
// ...skipping
public static final ch.qos.logback.classic.Level OFF;
public static final ch.qos.logback.classic.Level ERROR;
public static final ch.qos.logback.classic.Level WARN;
public static final ch.qos.logback.classic.Level INFO;
public static final ch.qos.logback.classic.Level DEBUG;
public static final ch.qos.logback.classic.Level TRACE;
public static final ch.qos.logback.classic.Level ALL;
}
===============>>#14 票数:0
使用slf4j API无法动态更改日志级别,但您可以自己配置logback(如果使用此项)。 在这种情况下,为您的记录器创建工厂类,并使用您需要的配置实现根记录器。
LoggerContext loggerContext = new LoggerContext();
ch.qos.logback.classic.Logger root = loggerContext.getLogger(org.slf4j.Logger.ROOT_LOGGER_NAME);
// Configure appender
final TTLLLayout layout = new TTLLLayout();
layout.start(); // default layout of logging messages (the form that message displays
// e.g. 10:26:49.113 [main] INFO com.yourpackage.YourClazz - log message
final LayoutWrappingEncoder encoder = new LayoutWrappingEncoder<>();
encoder.setCharset(StandardCharsets.UTF_8);
encoder.setLayout(layout);
final ConsoleAppender appender = new ConsoleAppender<>();
appender.setContext(loggerContext);
appender.setEncoder(encoder);
appender.setName("console");
appender.start();
root.addAppender(appender);
配置根记录器后(只需一次就足够了),您可以委派获取新的记录器
final ch.qos.logback.classic.Logger logger = loggerContext.getLogger(clazz);
请记住使用相同的loggerContext 。
使用loggerContext提供的root logger可以轻松更改日志级别。
root.setLevel(Level.DEBUG);
===============>>#15 票数:-2
使用java自省可以做到,例如:
private void changeRootLoggerLevel(int level) {
if (logger instanceof org.slf4j.impl.Log4jLoggerAdapter) {
try {
Class loggerIntrospected = logger.getClass();
Field fields[] = loggerIntrospected.getDeclaredFields();
for (int i = 0; i < fields.length; i++) {
String fieldName = fields[i].getName();
if (fieldName.equals("logger")) {
fields[i].setAccessible(true);
org.apache.log4j.Logger loggerImpl = (org.apache.log4j.Logger) fields[i]
.get(logger);
if (level == DIAGNOSTIC_LEVEL) {
loggerImpl.setLevel(Level.DEBUG);
} else {
loggerImpl.setLevel(org.apache.log4j.Logger.getRootLogger().getLevel());
}
// fields[i].setAccessible(false);
}
}
} catch (Exception e) {
org.apache.log4j.Logger.getLogger(LoggerSLF4JImpl.class).error("An error was thrown while changing the Logger level", e);
}
}
}
===============>>#16 票数:-6
不,它有很多方法,info(),debug(),warn()等(这取代了优先级字段)
ask by Edward Dale translate from so