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本文主要研究一下springboot的LogbackLoggingSystem
LoggingSystem
org/springframework/boot/logging/LoggingSystem.java
代码语言：javascript复制public abstract class LoggingSystem {
public abstract void beforeInitialize();
public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
}
public void cleanUp() {
}
public Runnable getShutdownHandler() {
return null;
}
public Set<LogLevel> getSupportedLogLevels() {
return EnumSet.allOf(LogLevel.class);
}
public void setLogLevel(String loggerName, LogLevel level) {
throw new UnsupportedOperationException("Unable to set log level");
}
public List<LoggerConfiguration> getLoggerConfigurations() {
throw new UnsupportedOperationException("Unable to get logger configurations");
}
public LoggerConfiguration getLoggerConfiguration(String loggerName) {
throw new UnsupportedOperationException("Unable to get logger configuration");
}
}LoggingSystem定义了beforeInitialize抽象方法，需要子类实现，，同时还提供了setLogLevel、getLoggerConfigurations、getLoggerConfiguration，默认是抛出UnsupportedOperationException
NoOpLoggingSystem
代码语言：javascript复制 static class NoOpLoggingSystem extends LoggingSystem {
@Override
public void beforeInitialize() {
}
@Override
public void setLogLevel(String loggerName, LogLevel level) {
}
@Override
public List<LoggerConfiguration> getLoggerConfigurations() {
return Collections.emptyList();
}
@Override
public LoggerConfiguration getLoggerConfiguration(String loggerName) {
return null;
}
}NoOpLoggingSystem继承了LoggingSystem，其方法都是空操作
AbstractLoggingSystem
org/springframework/boot/logging/AbstractLoggingSystem.java
代码语言：javascript复制public abstract class AbstractLoggingSystem extends LoggingSystem {
protected static final Comparator<LoggerConfiguration> CONFIGURATION_COMPARATOR = new LoggerConfigurationComparator(
ROOT_LOGGER_NAME);
private final ClassLoader classLoader;
public AbstractLoggingSystem(ClassLoader classLoader) {
this.classLoader = classLoader;
}
@Override
public void beforeInitialize() {
}
@Override
public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
if (StringUtils.hasLength(configLocation)) {
initializeWithSpecificConfig(initializationContext, configLocation, logFile);
return;
}
initializeWithConventions(initializationContext, logFile);
}
/**
* Load sensible defaults for the logging system.
* @param initializationContext the logging initialization context
* @param logFile the file to load or {@code null} if no log file is to be written
*/
protected abstract void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile);
/**
* Load a specific configuration.
* @param initializationContext the logging initialization context
* @param location the location of the configuration to load (never {@code null})
* @param logFile the file to load or {@code null} if no log file is to be written
*/
protected abstract void loadConfiguration(LoggingInitializationContext initializationContext, String location,
LogFile logFile);
/**
* Reinitialize the logging system if required. Called when
* {@link #getSelfInitializationConfig()} is used and the log file hasn't changed. May
* be used to reload configuration (for example to pick up additional System
* properties).
* @param initializationContext the logging initialization context
*/
protected void reinitialize(LoggingInitializationContext initializationContext) {
}
//......
} AbstractLoggingSystem继承了LoggingSystem，它主要是重写了initialize方法，若存在configLocation配置则执行initializeWithSpecificConfig，否则执行initializeWithConventions；它同时还定义了loadDefaults、loadConfiguration抽象方法需要子类实现
Slf4JLoggingSystem
org/springframework/boot/logging/Slf4JLoggingSystem.java
代码语言：javascript复制public abstract class Slf4JLoggingSystem extends AbstractLoggingSystem {
private static final String BRIDGE_HANDLER = "org.slf4j.bridge.SLF4JBridgeHandler";
public Slf4JLoggingSystem(ClassLoader classLoader) {
super(classLoader);
}
@Override
public void beforeInitialize() {
super.beforeInitialize();
configureJdkLoggingBridgeHandler();
}
@Override
public void cleanUp() {
if (isBridgeHandlerAvailable()) {
removeJdkLoggingBridgeHandler();
}
}
@Override
protected void loadConfiguration(LoggingInitializationContext initializationContext, String location,
LogFile logFile) {
Assert.notNull(location, "Location must not be null");
if (initializationContext != null) {
applySystemProperties(initializationContext.getEnvironment(), logFile);
}
}
//......
} Slf4JLoggingSystem继承了AbstractLoggingSystem，它覆盖了beforeInitialize，新增configureJdkLoggingBridgeHandler；其cleanUp方法在isBridgeHandlerAvailable的时候执行removeJdkLoggingBridgeHandler；其loadConfiguration在initializationContext不为null的时候执行applySystemProperties
configureJdkLoggingBridgeHandler
代码语言：javascript复制 private void configureJdkLoggingBridgeHandler() {
try {
if (isBridgeJulIntoSlf4j()) {
removeJdkLoggingBridgeHandler();
SLF4JBridgeHandler.install();
}
}
catch (Throwable ex) {
// Ignore. No java.util.logging bridge is installed.
}
}configureJdkLoggingBridgeHandler主要是判断是否将JUL绑定到SLF4J，是的话则removeJdkLoggingBridgeHandler，然后执行SLF4JBridgeHandler.install()
removeJdkLoggingBridgeHandler
代码语言：javascript复制 private void removeJdkLoggingBridgeHandler() {
try {
removeDefaultRootHandler();
SLF4JBridgeHandler.uninstall();
}
catch (Throwable ex) {
// Ignore and continue
}
}
private void removeDefaultRootHandler() {
try {
Logger rootLogger = LogManager.getLogManager().getLogger("");
Handler[] handlers = rootLogger.getHandlers();
if (handlers.length == 1 && handlers[0] instanceof ConsoleHandler) {
rootLogger.removeHandler(handlers[0]);
}
}
catch (Throwable ex) {
// Ignore and continue
}
}removeJdkLoggingBridgeHandler主要是执行removeDefaultRootHandler，以及SLF4JBridgeHandler.uninstall()
applySystemProperties
代码语言：javascript复制 protected final void applySystemProperties(Environment environment, LogFile logFile) {
new LoggingSystemProperties(environment).apply(logFile);
}
public void apply(LogFile logFile) {
PropertyResolver resolver = getPropertyResolver();
setSystemProperty(resolver, EXCEPTION_CONVERSION_WORD, "exception-conversion-word");
setSystemProperty(PID_KEY, new ApplicationPid().toString());
setSystemProperty(resolver, CONSOLE_LOG_PATTERN, "pattern.console");
setSystemProperty(resolver, FILE_LOG_PATTERN, "pattern.file");
setSystemProperty(resolver, FILE_CLEAN_HISTORY_ON_START, "file.clean-history-on-start");
setSystemProperty(resolver, FILE_MAX_HISTORY, "file.max-history");
setSystemProperty(resolver, FILE_MAX_SIZE, "file.max-size");
setSystemProperty(resolver, FILE_TOTAL_SIZE_CAP, "file.total-size-cap");
setSystemProperty(resolver, LOG_LEVEL_PATTERN, "pattern.level");
setSystemProperty(resolver, LOG_DATEFORMAT_PATTERN, "pattern.dateformat");
setSystemProperty(resolver, ROLLING_FILE_NAME_PATTERN, "pattern.rolling-file-name");
if (logFile != null) {
logFile.applyToSystemProperties();
}
} applySystemProperties通过LoggingSystemProperties设置了系统属性方便后续log配置文件使用
LogbackLoggingSystem
org/springframework/boot/logging/logback/LogbackLoggingSystem.java
代码语言：javascript复制public class LogbackLoggingSystem extends Slf4JLoggingSystem {
private static final String CONFIGURATION_FILE_PROPERTY = "logback.configurationFile";
private static final LogLevels<Level> LEVELS = new LogLevels<>();
static {
LEVELS.map(LogLevel.TRACE, Level.TRACE);
LEVELS.map(LogLevel.TRACE, Level.ALL);
LEVELS.map(LogLevel.DEBUG, Level.DEBUG);
LEVELS.map(LogLevel.INFO, Level.INFO);
LEVELS.map(LogLevel.WARN, Level.WARN);
LEVELS.map(LogLevel.ERROR, Level.ERROR);
LEVELS.map(LogLevel.FATAL, Level.ERROR);
LEVELS.map(LogLevel.OFF, Level.OFF);
}
private static final TurboFilter FILTER = new TurboFilter() {
@Override
public FilterReply decide(Marker marker, ch.qos.logback.classic.Logger logger, Level level, String format,
Object[] params, Throwable t) {
return FilterReply.DENY;
}
};
public LogbackLoggingSystem(ClassLoader classLoader) {
super(classLoader);
}
@Override
protected String[] getStandardConfigLocations() {
return new String[] { "logback-test.groovy", "logback-test.xml", "logback.groovy", "logback.xml" };
}
//......
} LogbackLoggingSystem继承了Slf4JLoggingSystem，其getStandardConfigLocations返回
logback-test.groovy, logback-test.xml, logback.groovy, logback.xml
beforeInitialize
代码语言：javascript复制 @Override
public void beforeInitialize() {
LoggerContext loggerContext = getLoggerContext();
if (isAlreadyInitialized(loggerContext)) {
return;
}
super.beforeInitialize();
loggerContext.getTurboFilterList().add(FILTER);
}beforeInitialize方法主要是添加了TurboFilter
initialize
代码语言：javascript复制 @Override
public void initialize(LoggingInitializationContext initializationContext, String configLocation, LogFile logFile) {
LoggerContext loggerContext = getLoggerContext();
if (isAlreadyInitialized(loggerContext)) {
return;
}
super.initialize(initializationContext, configLocation, logFile);
loggerContext.getTurboFilterList().remove(FILTER);
markAsInitialized(loggerContext);
if (StringUtils.hasText(System.getProperty(CONFIGURATION_FILE_PROPERTY))) {
getLogger(LogbackLoggingSystem.class.getName()).warn("Ignoring '" CONFIGURATION_FILE_PROPERTY
"' system property. Please use 'logging.config' instead.");
}
}initialize方法执行super.initialize(initializationContext, configLocation, logFile)，然后markAsInitialized(loggerContext)
loadDefaults
代码语言：javascript复制 @Override
protected void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile) {
LoggerContext context = getLoggerContext();
stopAndReset(context);
boolean debug = Boolean.getBoolean("logback.debug");
if (debug) {
StatusListenerConfigHelper.addOnConsoleListenerInstance(context, new OnConsoleStatusListener());
}
LogbackConfigurator configurator = debug ? new DebugLogbackConfigurator(context)
: new LogbackConfigurator(context);
Environment environment = initializationContext.getEnvironment();
context.putProperty(LoggingSystemProperties.LOG_LEVEL_PATTERN,
environment.resolvePlaceholders("${logging.pattern.level:${LOG_LEVEL_PATTERN:%5p}}"));
context.putProperty(LoggingSystemProperties.LOG_DATEFORMAT_PATTERN, environment.resolvePlaceholders(
"${logging.pattern.dateformat:${LOG_DATEFORMAT_PATTERN:yyyy-MM-dd HH:mm:ss.SSS}}"));
context.putProperty(LoggingSystemProperties.ROLLING_FILE_NAME_PATTERN, environment
.resolvePlaceholders("${logging.pattern.rolling-file-name:${LOG_FILE}.%d{yyyy-MM-dd}.%i.gz}"));
new DefaultLogbackConfiguration(initializationContext, logFile).apply(configurator);
context.setPackagingDataEnabled(true);
}loadDefaults方法通过LOG_LEVEL_PATTERN、LOG_DATEFORMAT_PATTERN、ROLLING_FILE_NAME_PATTERN以及LogbackConfigurator来初始化DefaultLogbackConfiguration
loadConfiguration
代码语言：javascript复制 @Override
protected void loadConfiguration(LoggingInitializationContext initializationContext, String location,
LogFile logFile) {
super.loadConfiguration(initializationContext, location, logFile);
LoggerContext loggerContext = getLoggerContext();
stopAndReset(loggerContext);
try {
configureByResourceUrl(initializationContext, loggerContext, ResourceUtils.getURL(location));
}
catch (Exception ex) {
throw new IllegalStateException("Could not initialize Logback logging from " location, ex);
}
List<Status> statuses = loggerContext.getStatusManager().getCopyOfStatusList();
StringBuilder errors = new StringBuilder();
for (Status status : statuses) {
if (status.getLevel() == Status.ERROR) {
errors.append((errors.length() > 0) ? String.format("%n") : "");
errors.append(status.toString());
}
}
if (errors.length() > 0) {
throw new IllegalStateException(String.format("Logback configuration error detected: %n%s", errors));
}
}
private void configureByResourceUrl(LoggingInitializationContext initializationContext, LoggerContext loggerContext,
URL url) throws JoranException {
if (url.toString().endsWith("xml")) {
JoranConfigurator configurator = new SpringBootJoranConfigurator(initializationContext);
configurator.setContext(loggerContext);
configurator.doConfigure(url);
}
else {
new ContextInitializer(loggerContext).configureByResource(url);
}
} loadConfiguration方法主要是执行configureByResourceUrl，该方法通过SpringBootJoranConfigurator或者ContextInitializer的configureByResource进行配置
小结
springboot定义了LoggingSystem、AbstractLoggingSystem、Slf4JLoggingSystem，依次继承，而LogbackLoggingSystem则继承Slf4JLoggingSystem，它主要是定义了要加载的默认的配置文件logback-test.groovy, logback-test.xml, logback.groovy, logback.xml，以及loadDefaults方法，通过LOG_LEVEL_PATTERN、LOG_DATEFORMAT_PATTERN、ROLLING_FILE_NAME_PATTERN以及LogbackConfigurator来初始化DefaultLogbackConfiguration。
