SSM项目运行时报错：java.lang.NoSuchMetho

Spring MVC发起请求时报错。

严重: Servlet.service() for servlet [dispatcher] in context with path [] threw exception [Handler dispatch failed; nested exception is java.lang.NoSuchMethodError: javax.servlet.http.HttpServletResponse.setContentLengthLong(J)V] with root cause
java.lang.NoSuchMethodError: javax.servlet.http.HttpServletResponse.setContentLengthLong(J)V
   at org.springframework.http.server.ServletServerHttpResponse.writeHeaders(ServletServerHttpResponse.java:130)
   at org.springframework.http.server.ServletServerHttpResponse.getBody(ServletServerHttpResponse.java:96)
   at org.springframework.http.converter.StringHttpMessageConverter.writeInternal(StringHttpMessageConverter.java:126)
   at org.springframework.http.converter.StringHttpMessageConverter.writeInternal(StringHttpMessageConverter.java:44)
   at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:227)
   at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:293)
   at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.handleReturnValue(RequestResponseBodyMethodProcessor.java:183)
   at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:78)
   at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:135)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
   at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
   at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
   at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067)
   at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
   at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
   at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
   at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
   at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
   at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
   at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
   at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
   at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
   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)

查阅了很多资料，确实是Spring web的版本到5.3以后加入了一行代码导致的。

if (contentLength != -1L) {
    this.servletResponse.setContentLengthLong(contentLength);
}

可能是少引入了jar包，但是到底是少引入了哪个，小编还没有找到。最后只能将spring的版本整体回退到5.3以下，不过问题总算是得到解决吧。