org.apache.logging.log4j.util.StackLocatorUtil#getCallerClass ( )源码实例Demo

@Override
public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext,
                                final URI configLocation) {
    if (currentContext) {
        final LoggerContext ctx = ContextAnchor.THREAD_CONTEXT.get();
        if (ctx != null) {
            return ctx;
        }
        return getDefault();
    }
    // it's quite possible that the provided ClassLoader may implement BundleReference which gives us a nice shortcut
    if (loader instanceof BundleReference) {
        return locateContext(((BundleReference) loader).getBundle(), configLocation);
    }
    final Class<?> callerClass = StackLocatorUtil.getCallerClass(fqcn);
    if (callerClass != null) {
        return locateContext(FrameworkUtil.getBundle(callerClass), configLocation);
    }
    final LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
    return lc == null ? getDefault() : lc;
}
 

@Override
public void shutdown(final String fqcn, final ClassLoader loader, final boolean currentContext,
                     final boolean allContexts) {
    LoggerContext ctx = null;
    if (currentContext) {
        ctx = ContextAnchor.THREAD_CONTEXT.get();
    } else if (loader != null) {
        ctx = findContext(loader);
    } else {
        final Class<?> clazz = StackLocatorUtil.getCallerClass(fqcn);
        if (clazz != null) {
            ctx = findContext(clazz.getClassLoader());
        }
        if (ctx == null) {
            ctx = ContextAnchor.THREAD_CONTEXT.get();
        }
    }
    if (ctx != null) {
        ctx.stop(DEFAULT_STOP_TIMEOUT, TimeUnit.MILLISECONDS);
    }
}
 

@Override
public boolean hasContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
    LoggerContext ctx;
    if (currentContext) {
        ctx = ContextAnchor.THREAD_CONTEXT.get();
    } else if (loader != null) {
        ctx = findContext(loader);
    } else {
        final Class<?> clazz = StackLocatorUtil.getCallerClass(fqcn);
        if (clazz != null) {
            ctx = findContext(clazz.getClassLoader());
        } else {
            ctx = ContextAnchor.THREAD_CONTEXT.get();
        }
    }
    return ctx != null && ctx.isStarted();
}
 

@Override
public LoggerContext getContext(final String fqcn, final ClassLoader loader, final boolean currentContext,
        final URI configLocation) {
    if (currentContext) {
        final LoggerContext ctx = ContextAnchor.THREAD_CONTEXT.get();
        if (ctx != null) {
            return ctx;
        }
        return getDefault();
    } else if (loader != null) {
        return locateContext(loader, configLocation);
    } else {
        final Class<?> clazz = StackLocatorUtil.getCallerClass(fqcn);
        if (clazz != null) {
            return locateContext(clazz.getClassLoader(), configLocation);
        }
        final LoggerContext lc = ContextAnchor.THREAD_CONTEXT.get();
        if (lc != null) {
            return lc;
        }
        return getDefault();
    }
}
 

private static Class<?> callerClass(final Class<?> clazz) {
    if (clazz != null) {
        return clazz;
    }
    final Class<?> candidate = StackLocatorUtil.getCallerClass(3);
    if (candidate == null) {
        throw new UnsupportedOperationException("No class provided, and an appropriate one cannot be found.");
    }
    return candidate;
}
 

public static String[] getCallStack() {
    int size = 100;
    int adviceStackEntryCount = 2;
    String[] callStack = new String[size];
    for (int i = 0; i < size; i++) {
        Class c = StackLocatorUtil.getCallerClass(i + adviceStackEntryCount);
        if (c == null) {
            return Arrays.copyOfRange(callStack, 0, i);
        }
        callStack[i] = c.getName();
    }
    return callStack;
}
 

@Benchmark
public Class<?>[] test11_getClassContextViaCallerClass() {
    // let's not benchmark LinkedList or anything here
    final Class<?>[] classes = new Class<?>[100];
    Class<?> clazz;
    for (int i = 0; null != (clazz = StackLocatorUtil.getCallerClass(i)); i++) {
        classes[i] = clazz;
    }
    return classes;
}
 

private static Class<?> callerClass(final Class<?> clazz) {
    if (clazz != null) {
        return clazz;
    }
    final Class<?> candidate = StackLocatorUtil.getCallerClass(3);
    if (candidate == null) {
        throw new UnsupportedOperationException("No class provided, and an appropriate one cannot be found.");
    }
    return candidate;
}
 

@Override
public void shutdown(final String fqcn, final ClassLoader loader, final boolean currentContext,
                     final boolean allContexts) {
    LoggerContext ctx = null;
    Bundle bundle = null;
    if (currentContext) {
        ctx = ContextAnchor.THREAD_CONTEXT.get();
        ContextAnchor.THREAD_CONTEXT.remove();
    }
    if (ctx == null && loader instanceof BundleReference) {
        bundle = ((BundleReference) loader).getBundle();
        ctx = getLoggerContext(bundle);
        removeLoggerContext(ctx);
    }
    if (ctx == null) {
        final Class<?> callerClass = StackLocatorUtil.getCallerClass(fqcn);
        if (callerClass != null) {
            bundle = FrameworkUtil.getBundle(callerClass);
            ctx = getLoggerContext(FrameworkUtil.getBundle(callerClass));
            removeLoggerContext(ctx);
        }
    }
    if (ctx == null) {
        ctx = ContextAnchor.THREAD_CONTEXT.get();
        ContextAnchor.THREAD_CONTEXT.remove();
    }
    if (ctx != null) {
        ctx.stop(DEFAULT_STOP_TIMEOUT, TimeUnit.MILLISECONDS);
    }
    if (bundle != null && allContexts) {
        final Bundle[] bundles = bundle.getBundleContext().getBundles();
        for (final Bundle bdl : bundles) {
            ctx = getLoggerContext(bdl);
            if (ctx != null) {
                ctx.stop(DEFAULT_STOP_TIMEOUT, TimeUnit.MILLISECONDS);
            }
        }
    }
}
 

@Override
public boolean hasContext(final String fqcn, final ClassLoader loader, final boolean currentContext) {
    if (currentContext && ContextAnchor.THREAD_CONTEXT.get() != null) {
        return ContextAnchor.THREAD_CONTEXT.get().isStarted();
    }
    if (loader instanceof BundleReference) {
        return hasContext(((BundleReference) loader).getBundle());
    }
    final Class<?> callerClass = StackLocatorUtil.getCallerClass(fqcn);
    if (callerClass != null) {
        return hasContext(FrameworkUtil.getBundle(callerClass));
    }
    return ContextAnchor.THREAD_CONTEXT.get() != null && ContextAnchor.THREAD_CONTEXT.get().isStarted();
}
 

@Benchmark
public Class<?> test07_getReflectiveCallerClassUtility() {
    return StackLocatorUtil.getCallerClass(3);
}
 

private Class<?> locateCaller() {
    return StackLocatorUtil.getCallerClass(ClassLocator.class.getName());
}
 

@Override
protected LoggerContext getContext() {
    final Class<?> anchor = StackLocatorUtil.getCallerClass(FQCN, PACKAGE);
    return anchor == null ? LogManager.getContext() : getContext(StackLocatorUtil.getCallerClass(anchor));
}
 

@Override
protected LoggerContext getContext() {
    final Class<?> anchor = StackLocatorUtil.getCallerClass(FQCN, PACKAGE);
    return anchor == null ? LogManager.getContext() : getContext(StackLocatorUtil.getCallerClass(anchor));
}