本文主要向大家介绍了JAVA语言之java.lang.NullPointerException引起的java.lang.ExceptionInInitializerError问题解析和解决办法，通过具体的内容向大家展示，希望对大家学习JAVA语言有所帮助。

 java.lang.NullPointerException  

    at java.io.Reader.<init>(Reader.java:78)  

    at java.io.InputStreamReader.<init>(InputStreamReader.java:97)  

    at com.mmall.utill.PropertiesUtil.<clinit>(PropertiesUtil.java:25)  

    at com.mmall.utill.MD5Util.MD5EncodeUtf8(MD5Util.java:52)  

    at com.mmall.service.impl.UserServiceImpl.login(UserServiceImpl.java:33)  

    at com.mmall.controller.portal.UserController.login(UserController.java:36)  

    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.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:214)  

    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)  

    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)  

    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:748)  

    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)  

    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)  

    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)  

    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)  

    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:931)  

    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:833)  

    at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)  

    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)  

    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)  

    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)  

    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)  

    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)  

    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)  

    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)  

    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)  

    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)  

    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)  

    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)  

    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)  

    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)  

    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474)  

    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)  

    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)  

    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624)  

    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)  

    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)  

    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)  

    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)  

    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)  

    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1437)  

    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)  

    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)  

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)  

    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)  

    at java.lang.Thread.run(Thread.java:745)

static{

   //String filename = "/mmall.properties";

   String filename = "mmall.properties";

   props = new Properties();

   try {

           props.load(new InputStreamReader(PropertiesUtil.class.getResourceAsStream(filename), "utf-8"));//该行报错

       } catch (IOException e) {

           logger.error("配置文件读取异常",e);

       }

}

filename使用上面的绝对地址（带斜杠的）就不报错，使用下面的相对地址就如上错误。

原因：相对地址找不到。

办法：使用斜杠开头的绝对地址

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