Class path contains multiple SLF4J binding
23-May-2019 16:04:25.300 INFO [localhost-startStop-1] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/admin/xxx/WEB-INF/lib/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/admin/xxx/WEB-INF/lib/logback-classic-1.1.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]

org.slf4j.impl.Log4jLoggerFactory cannot be cast to ch.qos.logback.classic.LoggerContext
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cn.com.xxx.framework.log.integration.LogbackInitializer#0' defined in class path resource [spring/spring-log-init.xml]: Invocation of init method failed; nested exception is java.lang.ClassCastException: org.slf4j.impl.Log4jLoggerFactory cannot be cast to ch.qos.logback.classic.LoggerContext
    ...
Caused by: java.lang.ClassCastException: org.slf4j.impl.Log4jLoggerFactory cannot be cast to ch.qos.logback.classic.LoggerContext
    # 出问题的加载地方
 at ch.qos.logback.ext.spring.LogbackConfigurer.initLogging(LogbackConfigurer.java:72)
 at cn.com.xxx.framework.log.integration.LogbackInitializer.init(LogbackInitializer.java:49)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:498)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1706)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1645)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
 ... 26 more

public static void initLogging(String location) throws FileNotFoundException, JoranException {
   String resolvedLocation = SystemPropertyUtils.resolvePlaceholders(location);
   URL url = ResourceUtils.getURL(resolvedLocation);
   LoggerContext loggerContext = (LoggerContext)StaticLoggerBinder.getSingleton().getLoggerFactory();
   loggerContext.reset();
   new ContextInitializer(loggerContext).configureByResource(url);

<dependency>
    <groupId>cn.com.xxx</groupId>
    <artifactId>framework-conf-client</artifactId>
    <version>${xqy.framework.version}</version>
    <exclusions>
        <exclusion>
            <artifactId>slf4j-log4j12</artifactId>
            <groupId>org.slf4j</groupId>
        </exclusion>
    </exclusions>
</dependency>

protected Class<?> loadClass(String name, boolean resolve)
    throws ClassNotFoundException
{
    synchronized (getClassLoadingLock(name)) {
        // First, check if the class has already been loaded
        // 首先，检查 class 是否已经被加载
        Class<?> c = findLoadedClass(name);
        if (c == null) {
            // 如果没有被加载
            long t0 = System.nanoTime();
            try {
                if (parent != null) {
                    // 寻找 parent 加载器
                    c = parent.loadClass(name, false);
                } else {
                    // 如果父加载器不存在，则委托给启动类加载器加载
                    c = findBootstrapClassOrNull(name);
                }
            } catch (ClassNotFoundException e) {
                // ClassNotFoundException thrown if class not found
                // from the non-null parent class loader
            }
            if (c == null) {
                // If still not found, then invoke findClass in order
                // to find the class.
                // 如果仍然无法加载，才会尝试自身加载
                long t1 = System.nanoTime();
                c = findClass(name);
                // this is the defining class loader; record the stats
                sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
                sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
                sun.misc.PerfCounter.getFindClasses().increment();
            }
        }
        if (resolve) {
            resolveClass(c);
        }
        return c;
    }
}