SLF4J: Failed to load class "org

今天在搭建系统的时候，报了下面错误

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder"
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

查到到这些错误实在slf4j-api的jar中的LoggerFactory类中 bind()方法抛出的

private final static void bind() {
        try {
            Set<URL> staticLoggerBinderPathSet = null;
            // skip check under android, see also
            // http://jira.qos.ch/browse/SLF4J-328
            if (!isAndroid()) {
                staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();
                reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);
            }
            // the next line does the binding
            StaticLoggerBinder.getSingleton();
            INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;
            reportActualBinding(staticLoggerBinderPathSet);
            fixSubstituteLoggers();
            replayEvents();
            // release all resources in SUBST_FACTORY
            SUBST_FACTORY.clear();
        } catch (NoClassDefFoundError ncde) {
            String msg = ncde.getMessage();
            if (messageContainsOrgSlf4jImplStaticLoggerBinder(msg)) {
                INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION;
                Util.report("Failed to load class \"org.slf4j.impl.StaticLoggerBinder\".");
                Util.report("Defaulting to no-operation (NOP) logger implementation");
                Util.report("See " + NO_STATICLOGGERBINDER_URL + " for further details.");
            } else {
                failedBinding(ncde);
                throw ncde;
            }
        }

只贴出部分代码，上面代码报错的原因是StaticLoggerBinder.getSingleton();代码找不到StaticLoggerBinder这个类，这个类定义是在org.slf4j.impl.StaticLoggerBinder下面，但是slf4j-api包中没有实现这个类，而是交给终端用户指定，带来很大的灵活性。

slf4j-api包

从上面图也可以看出没有定义impl这个package，没有任何的实现类，所以要让这个不报错，还需要导入其他的jar包实现了StaticLoggerBinder这个类。从网上找了一下，有些jar包都实现了这个类。

slf4j-log4j12.jar (for log4j logging),
slf4j-jdk14.jar (for Java logging),
slf4j-jcl.jar (if you’re using Commons logging)
logback-classic.jar (for logback logging).

只要引入相应的jar包即可解决这个问题。现在引入jdk的包slf4j-jdk14.jar

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-jdk14</artifactId>
            <version>1.7.25</version>
        </dependency>

jdk实现

从上面的图中可以看到，包名和slf4j-api一样。