Servlet> 3.0上的NoSuchMethodError HttpServletRequest.getServletContext（） [英] NoSuchMethodError HttpServletRequest.getServletContext() on Servlet >3.0

问题描述

我已经根据本指南，并根据这一个。但是，当我运行 gradle jettyRun 并尝试打开连接时（使用这个）到 ws：// localhost：8080 / myProjectName / echo ），我得到 java.lang.NoSuchMethodError：javax.servlet.http.HttpServletRequest.getServletContext（）（）

我参见这个方法仅在servlet 3.0中引入 - 但是，因为我使用 servlet-api：3.1.0



我相当确定我的 WEB-INF / web.xml中的路由是正确的，因为当我尝试点击另一个URL（例如 ws：// localhost：8080 / myProjectName / echo123 ）时， t上得到错误输出终端。



---

文件：

build.gradle：

  apply plugin：'java'
 apply plugin：'jetty'
 
 sourceCompatibility = 1.5 
 version ='1.0'
 
存储库{
 mavenCentral（）
} 
 
依赖关系{
 compile'javax.servlet ：javax.servlet-api：3.1.0'
 compile'org.eclipse.jetty：jetty-server：9.3.2.v20150730'
 compile'org.eclipse.jetty.websocket：websocket-servlet ：9.0.0.M3'
 compile'org.eclipse.jetty.aggregate：jetty-all：9.1.3.v20140225'
 testCompile组：'junit'，名称：'junit'，版本： '4.11'
} 
  

src / main / webapp / WEB-INF / web.xml

 <？xml version =1.0encoding =utf-8？> 
< web-app xmlns：xsi =http://www.w3.org/2001/XMLSchema-instance
 xmlns =http://java.sun.com/xml/ns / javaee
 xmlns：web =http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd
 xsi：schemaLocation =http：//java.sun .com / xml / ns / javaee 
 http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd
 id =WebApp_IDversion =3.0> 
 
< servlet> 
< servlet-name> EchoServlet< / servlet-name> 
< servlet-class> org.scubbo.myprojectname.EchoServlet< / servlet-class> 
< / servlet> 
< servlet-mapping> 
< servlet-name> EchoServlet< / servlet-name> 
< url-pattern> / echo< / url-pattern> 
< / servlet-mapping> 
< / web-app> 
  

src / main / java / org / scubbo / myprojectname / EchoServlet.java

  package org.scubbo.myprojectname; 
 
导入org.eclipse.jetty.websocket.servlet.WebSocketServlet; 
 import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory; 
 import org.scubbo.myprojectname.sockets.EchoSocket; 
 
 public class EchoServlet extends WebSocketServlet {
 $ b $ @Override 
 public void configure（WebSocketServletFactory factory）{
 factory.getPolicy（）。setIdleTimeout（10000） ; 
 factory.register（EchoSocket.class）; 
 
 
 
 $ s 
 $ src / main / java / org / scubbo / myprojectname / sockets / EchoSocket。 java 
  package org.scubbo.myprojectname.sockets; 
 
导入org.eclipse.jetty.websocket.api.Session; 
导入org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage; 
 import org.eclipse.jetty.websocket.api.annotations.WebSocket; 
 
 @WebSocket 
 public class EchoSocket {
 
 @OnWebSocketMessage $ b $ public void onText（Session session，String message）{
 if（session .isOpen（））{
 System.out.printf（回声消息[％s]％n，message）; 
 session.getRemote（）。sendString（message，null）; 
 
 
 
 $ b  
 
 
解决方案
你遇到的最初的问题是你的类路径中有2个相互冲突的servlet api版本（这并不罕见，因为这个工件有6个奇怪的maven坐标，这使得解决冲突对于maven或gradle很困难） 
 
 
不要在项目中使用jetty-all，这个工件不能用于项目。请参阅过去对此的回应。
 
 
 
你在使用WebSocket支持时遇到的问题应该作为一个单独的问题提交到stackoverflow。
 
 
 
询问有关websocket问题的具体问题，我会在那里回答。
 
I'm trying to set up a WebSocketServlet in Jetty.

I've set up a servlet according to this guide, and implemented the WebSocket according to this one. However, when I run gradle jettyRun and attempt to open a connection (using this) to ws://localhost:8080/myProjectName/echo), I get java.lang.NoSuchMethodError: javax.servlet.http.HttpServletRequest.getServletContext() (full stacktrace)

I see that this method was only introduced in servlet 3.0 - however, since I'm using servlet-api:3.1.0, I believe I should have that method?

I'm reasonably sure that the routing in my WEB-INF/web.xml is correct, since when I try to hit another url (ws://localhost:8080/myProjectName/echo123, for instance), I don't get error output on the terminal.



Files:

build.gradle:
apply plugin: 'java'
apply plugin : 'jetty'

sourceCompatibility = 1.5
version = '1.0'

repositories {
    mavenCentral()
}

dependencies {
    compile 'javax.servlet:javax.servlet-api:3.1.0'
    compile 'org.eclipse.jetty:jetty-server:9.3.2.v20150730'
    compile 'org.eclipse.jetty.websocket:websocket-servlet:9.0.0.M3'
    compile 'org.eclipse.jetty.aggregate:jetty-all:9.1.3.v20140225'
    testCompile group: 'junit', name: 'junit', version: '4.11'
}
src/main/webapp/WEB-INF/web.xml
<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         id="WebApp_ID" version="3.0">

    <servlet>
        <servlet-name>EchoServlet</servlet-name>
        <servlet-class>org.scubbo.myprojectname.EchoServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>EchoServlet</servlet-name>
        <url-pattern>/echo</url-pattern>
    </servlet-mapping>
</web-app>
src/main/java/org/scubbo/myprojectname/EchoServlet.java
package org.scubbo.myprojectname;

import org.eclipse.jetty.websocket.servlet.WebSocketServlet;
import org.eclipse.jetty.websocket.servlet.WebSocketServletFactory;
import org.scubbo.myprojectname.sockets.EchoSocket;

public class EchoServlet extends WebSocketServlet {

    @Override
    public void configure(WebSocketServletFactory factory) {
        factory.getPolicy().setIdleTimeout(10000);
        factory.register(EchoSocket.class);
    }
src/main/java/org/scubbo/myprojectname/sockets/EchoSocket.java
package org.scubbo.myprojectname.sockets;

import org.eclipse.jetty.websocket.api.Session;
import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
import org.eclipse.jetty.websocket.api.annotations.WebSocket;

@WebSocket
public class EchoSocket {

    @OnWebSocketMessage
    public void onText(Session session, String message) {
        if (session.isOpen()) {
            System.out.printf("Echoing back message [%s]%n", message);
            session.getRemote().sendString(message, null);
        }
    }

}

解决方案
The original problem you are having is that you had 2 conflicting versions of the servlet api in your classpath (not that uncommon, as there's a half-dozen odd maven coordinates for that artifact, which makes conflict resolution difficult for maven or gradle)

Don't use jetty-all with your project, that artifact isn't meant to be used from a project.  See past responses about this.

The problem you are having with WebSocket support should be filed as a separate question on stackoverflow.

Ask a specific question about your websocket issue, and I'll answer there.

                        
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