如何在Spring Boot应用程序中配置Servlet初始化参数

Question

我有一个使用Spring MVC的Spring引导应用程序（版本1.2.1RELEASE），我需要在JspServlet上设置开发初始化参数。在web.xml中，其外观如下所示：

<servlet>
        <servlet-name>jsp</servlet-name>
        <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
        ...
        <init-param>
            <param-name>development</param-name>
            <param-value>false</param-value>
        </init-param>
         ...
</servlet>

我以为我可以做这样的事情：如何像在web.xml中那样配置spring-boot servlet？，但我不认为可以用新的JspServlet（）替换新的MeteorServlet（）并继续前进，因为我确定需要使用有效的ServletConfig调用JspServlet.init（ServletConfig config）。而且，当然，如果我在初始化时没有进行适当的尝试，该应用程序就会给我一个空指针异常（之所以发生，是因为私有的瞬时JspRuntimeContext rctxt;为空）：

java.lang.NullPointerException: null
    at org.apache.jasper.servlet.JspServlet.periodicEvent(JspServlet.java:361)
    at org.apache.catalina.core.StandardWrapper.backgroundProcess(StandardWrapper.java:679)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1377)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1381)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1349)
    at java.lang.Thread.run(Thread.java:745)

此外，通过实现TomcatEmbeddedServletContainerFactory并提供一个Servlet来覆盖ServletConfig的init方法和getInitParameter方法，我们有一种真正的技巧来做到这一点，但它有点令人讨厌，所以我希望有更好的方法。任何指导将不胜感激。

最后，读取此init-param的代码在org.apache.jasper.EmbeddedServletOptions类中，并且似乎仅查找ServletConfig init参数，因此我无法将其指定为上下文参数（我认为）诸如server.context-parameters.name = value之类的很棒的东西。

String development = config.getInitParameter("development");
if (development != null) {
    if (development.equalsIgnoreCase("true")) {
        this.development = true;
    } else if (development.equalsIgnoreCase("false")) {
        this.development = false;
    } else {
        if (log.isWarnEnabled()) {
            log.warn(Localizer.getMessage("jsp.warning.development"));
        }
    }

}

而且，如果我仍然尝试点击该应用程序，则会出现以下错误：

java.lang.StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(String.java:646)
at org.apache.jasper.compiler.JspUtil.makeJavaIdentifier(JspUtil.java:833)
at org.apache.jasper.compiler.JspUtil.makeJavaIdentifier(JspUtil.java:806)
at org.apache.jasper.JspCompilationContext.getServletClassName(JspCompilationContext.java:332)
at org.apache.jasper.JspCompilationContext.getClassFileName(JspCompilationContext.java:504)
at org.apache.jasper.compiler.Compiler.isOutDated(Compiler.java:444)
at org.apache.jasper.compiler.Compiler.isOutDated(Compiler.java:408)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:557)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:335)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:291)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:186)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.boot.actuate.autoconfigure.MetricFilterAutoConfiguration$MetricsFilter.doFilterInternal(MetricFilterAutoConfiguration.java:90)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:534)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1081)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:658)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523)
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)

Answer 1

有人为我找到了这个链接，它看起来效果很好，所以我将使用它，除非有人提出更好的选择 - http://fqa.io/questions/28863340/springboot-embedded-tomcat- jspservlet 选项

    @Bean
public EmbeddedServletContainerCustomizer customizer() {
    return new EmbeddedServletContainerCustomizer() {

        @Override
        public void customize(ConfigurableEmbeddedServletContainer container) {
            if (container instanceof TomcatEmbeddedServletContainerFactory) {
                customizeTomcat((TomcatEmbeddedServletContainerFactory) container);
            }
        }

        private void customizeTomcat(
                TomcatEmbeddedServletContainerFactory tomcat) {
            tomcat.addContextCustomizers(new TomcatContextCustomizer() {
                @Override
                public void customize(Context context) {
                    Wrapper jsp = (Wrapper) context.findChild("jsp");
                    jsp.addInitParameter("development", development);
                }
            });
        }
    };
}