java.lang.NoClassDefFoundError：org / slf4j / LoggerFactory即使我有正確的依賴關系

Question

我真的很忙。 我試圖將一些加密代碼從一個項目復制到另一個項目-一個實際上只是另一個項目的一個分支。 對項目的更改很小（某些樣式和格式更改），但是一個可行，而另一個則出現此錯誤：

HTTP Status 500 - Request processing failed; nested exception is java.lang.NullPointerException

type Exception report

message Request processing failed; nested exception is java.lang.NullPointerException

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:981)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:871)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

java.lang.NullPointerException
    com.grandcircus.spring.util.GateKeeper.getSecretKey(GateKeeper.java:47)
    com.grandcircus.spring.util.GateKeeper.setLock(GateKeeper.java:28)
    com.grandcircus.spring.controller.HomeController.registerChaplainSubmit(HomeController.java:157)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:969)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:871)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:845)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

我在部署終端中收到此警告：

log4j:WARN No appenders could be found for logger (org.springframework.web.servlet.DispatcherServlet).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
[2017-06-21 01:17:58,132] Artifact SpringTemplate:war exploded: Artifact is deployed successfully
[2017-06-21 01:17:58,132] Artifact SpringTemplate:war exploded: Deploy took 4,536 milliseconds
21-Jun-2017 13:18:03.131 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory C:\Program Files\Apache\apache-tomcat-8.0.43\webapps\manager
21-Jun-2017 13:18:03.178 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory C:\Program Files\Apache\apache-tomcat-8.0.43\webapps\manager has finished in 47 ms

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.

這是我的依賴項列表：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.grandcircus.spring</groupId>
    <artifactId>first-time-out-program</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>4.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>4.2.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>4.2.9.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.1.3</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>javassist</groupId>
            <artifactId>javassist</artifactId>
            <version>3.12.1.GA</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>3.6.3.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.4.Final</version>
        </dependency>

        <!--below are fixes for 500 error -->
        <dependency>
            <groupId>org.apache.taglibs</groupId>
            <artifactId>taglibs-standard-spec</artifactId>
            <version>1.2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.taglibs</groupId>
            <artifactId>taglibs-standard-impl</artifactId>
            <version>1.2.5</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.1</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-c3p0</artifactId>
            <version>3.6.3.Final</version>
        </dependency>

        <!-- Dependencies needed for email validation API -->
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.1</version>
        </dependency>
        <dependency>
            <groupId>com.googlecode.json-simple</groupId>
            <artifactId>json-simple</artifactId>
            <version>1.1</version>
        </dependency>
        <dependency>
            <groupId>org.json</groupId>
            <artifactId>json</artifactId>
            <version>20090211</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>servlet-api</artifactId>
            <version>2.5</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.22</version>
        </dependency>
    </dependencies>
</project>

這已經使我瘋狂了好幾個小時，在這里找到的任何答案都必須比我有更高的智商，因為這對我來說全是希臘語。 到底發生了什么事，為什么我是唯一遇到此問題的人，僅在項目的此特定分支上才遇到此問題？ 這沒有道理！

Answer 1

您的apache / tomcat（catalina）的類加載器無法通過反射找到LoggerFactory，這可能是由類路徑中的大量日志依賴項引起的。

請嘗試從您的POM中刪除

<dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.5</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.5</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.6</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.1.3</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>1.1.3</version>
    </dependency>

並替換為

<dependency>
<groupId><org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.22</version>
</dependency>

希望對您有用。