java - 【已解决】Jetty 9.3 无法使用 JSP

Question

原来我使用 jetty 9.2.17，一直都很正常；最近想使用标准的 websocket，先将 jetty 升级到 9.3.10。原来 JSP 支持使用 jetty-jsp，升级后改为 jetty 的 apache-jsp (版本与其他 jetty 组件相同，官方换了包名而已，依赖 apache 的 apache-jsp 8.0.33)，Servlet 一切正常，但 JSP 都无法使用了，报错：

java.lang.NullPointerException
    at org.apache.jasper.compiler.Validator$ValidateVisitor.<init>(Validator.java:515)
    at org.apache.jasper.compiler.Validator.validateExDirectives(Validator.java:1853)
    at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:217)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:356)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:336)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:323)
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:585)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:363)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:837)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:583)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:511)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
    at org.eclipse.jetty.server.Server.handle(Server.java:524)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:319)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:253)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:273)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:95)
    at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589)
    at java.lang.Thread.run(Thread.java:745)

搜了一圈，也看了 jetty 官方的文档，尝试了 web.xml 中设置 jsp servlet，设置其他属性，增加额外的包，均无效。请问有遇到过类似问题的朋友吗？你是如何解决的。

Answer 1

Finally solved this problem, refer to https://github.com/jetty-proj...

After the jetty version is upgraded from 9.2.17 to 9.3.1x, the original WebAppContext only needs to simply set the ContextPath and ResourceBase. Now it is necessary to set some additional properties. In addition to relying on the apache-jsp package, the jetty-plus package also needs to be introduced. to get ContainerInitializer. The following is the code written with reference to the example:

    // 构建应用
    WebAppContext webapp  = new WebAppContext();
    webapp.setDescriptor   (conf);
    webapp.setContextPath  (Core.BASE_HREF);
    webapp.setResourceBase (Core.BASE_PATH);
    webapp.setParentLoaderPriority ( true );

    // JSP 相关
    webapp.setTempDirectory(temp);
    webapp.setAttribute("javax.servlet.context.tempdir", temp);
    // 下面是为解决此次问题增加的代码
    webapp.setAttribute("org.eclipse.jetty.containerInitializers" , Arrays.asList (
                       new ContainerInitializer(new JettyJasperInitializer(), null)));
    webapp.setAttribute(InstanceManager.class.getName(), new SimpleInstanceManager());