java 编译异常及其解决办法（持续更新）

java 编译异常及其解决办法（持续更新）

1.解决办法：将jar版本降低适配 低版本的jdk或tomcat

严重: ContainerBase.addChild: start: 
org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/EasyGo]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:754)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1140)
    at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1875)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.UnsupportedClassVersionError: org/springframework/web/SpringServletContainerInitializer : Unsupported major.minor version 52.0 (unable to load class [org.springframework.web.SpringServletContainerInitializer])
    at org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2341)
    at org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:828)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1277)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1136)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:278)
    at org.apache.catalina.startup.WebappServiceLoader.loadServices(WebappServiceLoader.java:188)
    at org.apache.catalina.startup.WebappServiceLoader.load(WebappServiceLoader.java:159)
    at org.apache.catalina.startup.ContextConfig.processServletContainerInitializers(ContextConfig.java:1612)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1125)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:765)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5154)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 10 more
十二月 26, 2018 10:34:42 上午 org.apache.catalina.startup.HostConfig deployDirectory
严重: Error deploying web application directory [D:softwaremyeclipseapache-tomcat-8.5.31webappsEasyGo]
java.lang.IllegalStateException: ContainerBase.addChild: start: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/EasyGo]]
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:758)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:730)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1140)
    at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1875)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

 2.解决办法：点击该项目->properties->Deployment Assmebly->Add->Java Build Path Entries（手动将项目所需要的jar添加）

    问题：使用tomcat运行Dynamic Web Project时，在webapps中的项目没有加载jar包

3.空指针:java NullPointerException 可能是包未导入。

4.解决方法：添加jar包javassist

　问题：java.lang.ClassNotFoundException: javassist.ClassPath

5.解决方法：正常情况下springmvc的xml文件应放在WEB-INF下，命名规则为 [name]-servlet.xml “-servlet”这个字段是必不可少的 [name]你可以随便命名 但是为了规范和方便阅读 最好是springmvc-servlet.xml(我这里是测试随便起的) 同时你的xml文件中两个servlet要和你的name相同 不然会报错的,对应此处的HelloWeb,所以需要使用HelloWeb-servlet.xml。

  问题：找不到xml

org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from ServletContext resource [/WEB-INF/HelloWeb-servlet.xml]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/WEB-INF/HelloWeb-servlet.xml]

6.解决方法：把 https 改为 http

  问题：

java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names must be tokens

 7.解决方法：将attach 类型改为class AttachBean{Map<String,Object> tinfo}

问题：使用Gson自动化将json转化为javaBean的时候，属性String attach无法正确解析。因为收到的attach不是String类型，而是一个嵌套json

"attach": {
　　"tinfo": {
　　"22": "0"
　　}
},

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected a string but was BEGIN_OBJECT at line 1 column 280 path $.attach