SpringBoot项目打WAR包在Tomcat启动问题记录

环境
jdk1.8
springboot 2.0.3.RELEASE
maven 3.5.0
tomcat 7、8

jar包和war包启动区别
jar包:执行SpringBootApplication的run方法,启动IOC容器,然后创建嵌入式Servlet容器
war包:  先是启动Servlet服务器,服务器启动Springboot应用(springBootServletInitizer),然后启动IOC容器

1. 打包部署到外部Tomcat，访问时404

原理

SpringBootServletInitializer的执行过程，简单来说就是通过SpringApplicationBuilder构建并封装			      SpringApplication对象，并最终调用SpringApplication的run方法的过程。

spring boot就是为了简化开发的，也就是用注解的方式取代了传统的xml配置。

SpringBootServletInitializer就是原有的web.xml文件的替代。

使用了嵌入式Servlet,默认是不支持jsp。

SpringBootServletInitializer 可以使用外部的Servlet容器，使用步骤：

  1.必须创建war项目，需要创建好web项目的目录。2.嵌入式Tomcat依赖scope指定provided。3.编写SpringBootServletInitializer类子类,并重写configure方法。

原文链接

---

需要在mail启动类继承SpringBootServletInitializer

 @SpringBootApplication
 public class MainApplication extends SpringBootServletInitializer {
     @Override
     protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
         return builder.sources(MainApplication.class);
     }
     public static void main(String[] args) {
         SpringApplication.run(MainApplication.class, args);
 	}
 }

2.war包启动时报错如下

05-Sep-2019 11:52:43.545 严重 [localhost-startStop-1] org.apache.catalina.core.ContainerBase.addChildInternal ContainerBase.addChild: start: 
	org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]
		at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
		at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:743)
		at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:719)
		at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
		at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:970)
		at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1841)
		at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
		at java.util.concurrent.FutureTask.run(FutureTask.java:266)
		at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
		at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
		at java.lang.Thread.run(Thread.java:748)
	Caused by: java.lang.StackOverflowError
		at org.apache.logging.log4j.util.StackLocator.getCallerClass(StackLocator.java:112)
		at org.apache.logging.log4j.util.StackLocator.getCallerClass(StackLocator.java:125)
		at org.apache.logging.log4j.util.StackLocatorUtil.getCallerClass(StackLocatorUtil.java:55)
		at org.apache.logging.slf4j.Log4jLoggerFactory.getContext(Log4jLoggerFactory.java:42)
		at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:46)
		at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:29)
		.......
		.......
		
05-Sep-2019 11:52:43.556 严重 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployWAR Error deploying web application archive [/Users/gb/worktool/apache-tomcat-8.5.45/webapps/ROOT.war]
	java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]
		at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:747)
		at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:719)
		at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:714)
		at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:970)
		at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1841)
		at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
		at java.util.concurrent.FutureTask.run(FutureTask.java:266)
		at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
		at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
		at java.lang.Thread.run(Thread.java:748)

问题的原因是jar包冲突导致

通过 mvn dependency:tree
或者IDEA的 maven 插件查看冲突的jar包

			
                
                    slf4j-api
                    org.slf4j
                
                
                    log4j-slf4j-impl
                    org.apache.logging.log4j
                
                
                    jcl-over-slf4j
                    org.slf4j