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如何使用Eclipse為Jetty編寫簡單的Servlet？

[英]How do I write a simple Servlet for Jetty using Eclipse?

 原文  2012-01-30 02:08:50  0   2    java/ eclipse/ servlets/ jetty/ war

問題描述

我下載了Eclipse for Java EE和Jetty 8.1，並希望實現一個非常簡單的Servlet。

當我使用java -jar start.jar啟動它時，Jetty工作正常。

為了開發Servlet，我做了這個：

  1. 在Eclipse中，我選擇了“New Dynamic Web Project”。

  2. 我將jetty\\lib\\servlet-api-3.0.jar到Eclipse中的“Build Path”。

  3. 在該項目中，生成了“New Servlet”和Servlet，並添加了一些代碼： 

     /** * Servlet implementation class MyServlet */ @WebServlet("/MyServlet") public class MyServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getWriter(); out.println("<html><body><h1>My Servlet</h1></body></html>"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub } }

  4. 我在WebContent\\WEB-INF\\web.xml創建了一個文件web.xml ，其中包含以下內容： 

     <?xml version="1.0" encoding="utf-8" ?> <web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4"> <servlet> <servlet-name>My Servlet</servlet-name> <servlet-class>MyServlet.class</servlet-class> </servlet> <servlet-mapping> <servlet-name>My Servlet</servlet-name> <url-pattern>/Servlet</url-pattern> </servlet-mapping>

  5. 我將build\\classes編譯的.class -files復制到WebContent\\WEB-INF\\classes

  6. 現在我選擇將項目導出為.war -file到jetty\\webapps\\MySite.war 。

  7. 我用java -jar start.jar啟動Jetty並訪問localhost:8080/MySite/Servlet但現在我收到此消息： 

     Servlet Not Initialized javax.servlet.UnavailableException: Servlet Not Initialized at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:546) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:485) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:483) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:233) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1065) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:412) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:192) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:999) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:111) at org.eclipse.jetty.server.Server.handle(Server.java:351) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:451) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:916) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:647) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:233) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:76) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:615) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:45) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:599) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:534) at java.lang.Thread.run(Thread.java:722)

如果我訪問localhost:8080/MySite/我看到兩個文件夾WEB-INF\\和META-INF\\都是大小為0 bytes 。

所以它看起來不像我在Eclipse中的.war -export工作。

如何使用Eclipse導出我的簡單Servlet for Jetty？

我現在已經為Eclipse安裝了Jetty WTP插件 ，但是我無法使用它來運行這個servlet： 

2012-01-30 10:06:50.322:INFO:oejs.Server:jetty-8.1.0.RC4
2012-01-30 10:06:50.353:INFO:oejdp.ScanningAppProvider:Deployment monitor C:\Users\Jonas\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\webapps at interval 1
2012-01-30 10:06:50.353:INFO:oejdp.ScanningAppProvider:Deployment monitor C:\Users\Jonas\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\contexts at interval 1
2012-01-30 10:06:50.353:INFO:oejd.DeploymentManager:Deployable added: C:\Users\Jonas\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\contexts\MySite.xml
2012-01-30 10:06:50.650:WARN:oejuc.AbstractLifeCycle:FAILED o.e.j.w.WebAppContext{/MySite,file:/C:/Users/Jonas/workspace/.metadata/.plugins/org.eclipse.wst.server.core/tmp0/wtpwebapps/MySite/},C:\Users\Jonas\workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0/wtpwebapps/MySite: java.lang.NoClassDefFoundError: org/objectweb/asm/ClassVisitor
java.lang.NoClassDefFoundError: org/objectweb/asm/ClassVisitor
    at org.eclipse.jetty.annotations.AnnotationConfiguration.createAnnotationParser(AnnotationConfiguration.java:111)
    at org.eclipse.jetty.annotations.AnnotationConfiguration.configure(AnnotationConfiguration.java:73)
    at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:428)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1208)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:699)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:454)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.bindings.StandardStarter.processBinding(StandardStarter.java:36)
    at org.eclipse.jetty.deploy.AppLifeCycle.runBindings(AppLifeCycle.java:183)
    at org.eclipse.jetty.deploy.DeploymentManager.requestAppGoal(DeploymentManager.java:491)
    at org.eclipse.jetty.deploy.DeploymentManager.addApp(DeploymentManager.java:138)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider.fileAdded(ScanningAppProvider.java:142)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider$1.fileAdded(ScanningAppProvider.java:53)
    at org.eclipse.jetty.util.Scanner.reportAddition(Scanner.java:604)
    at org.eclipse.jetty.util.Scanner.reportDifferences(Scanner.java:535)
    at org.eclipse.jetty.util.Scanner.scan(Scanner.java:398)
    at org.eclipse.jetty.util.Scanner.doStart(Scanner.java:332)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider.doStart(ScanningAppProvider.java:118)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.DeploymentManager.startAppProvider(DeploymentManager.java:552)
    at org.eclipse.jetty.deploy.DeploymentManager.doStart(DeploymentManager.java:227)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.util.component.AggregateLifeCycle.doStart(AggregateLifeCycle.java:58)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:53)
    at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:91)
    at org.eclipse.jetty.server.Server.doStart(Server.java:263)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1214)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1137)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.jetty.start.Main.invokeMain(Main.java:457)
    at org.eclipse.jetty.start.Main.start(Main.java:600)
    at org.eclipse.jetty.start.Main.main(Main.java:82)
Caused by: 
java.lang.ClassNotFoundException: org.objectweb.asm.ClassVisitor
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at org.eclipse.jetty.annotations.AnnotationConfiguration.createAnnotationParser(AnnotationConfiguration.java:111)
    at org.eclipse.jetty.annotations.AnnotationConfiguration.configure(AnnotationConfiguration.java:73)
    at org.eclipse.jetty.webapp.WebAppContext.configure(WebAppContext.java:428)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1208)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:699)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:454)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.bindings.StandardStarter.processBinding(StandardStarter.java:36)
    at org.eclipse.jetty.deploy.AppLifeCycle.runBindings(AppLifeCycle.java:183)
    at org.eclipse.jetty.deploy.DeploymentManager.requestAppGoal(DeploymentManager.java:491)
    at org.eclipse.jetty.deploy.DeploymentManager.addApp(DeploymentManager.java:138)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider.fileAdded(ScanningAppProvider.java:142)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider$1.fileAdded(ScanningAppProvider.java:53)
    at org.eclipse.jetty.util.Scanner.reportAddition(Scanner.java:604)
    at org.eclipse.jetty.util.Scanner.reportDifferences(Scanner.java:535)
    at org.eclipse.jetty.util.Scanner.scan(Scanner.java:398)
    at org.eclipse.jetty.util.Scanner.doStart(Scanner.java:332)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.providers.ScanningAppProvider.doStart(ScanningAppProvider.java:118)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.deploy.DeploymentManager.startAppProvider(DeploymentManager.java:552)
    at org.eclipse.jetty.deploy.DeploymentManager.doStart(DeploymentManager.java:227)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.util.component.AggregateLifeCycle.doStart(AggregateLifeCycle.java:58)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:53)
    at org.eclipse.jetty.server.handler.HandlerWrapper.doStart(HandlerWrapper.java:91)
    at org.eclipse.jetty.server.Server.doStart(Server.java:263)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:59)
    at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1214)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1137)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.jetty.start.Main.invokeMain(Main.java:457)
    at org.eclipse.jetty.start.Main.start(Main.java:600)
    at org.eclipse.jetty.start.Main.main(Main.java:82)

2 個解決方案

解決方案1
 8 已采納  2012-01-30 19:11:24

首先，你的web.xml是錯誤的。

servlet-class元素包含servlet的完全限定類名。

從web.xml架構開始，您在第923行使用了http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd 。因此，第9行的servlet-class元素的內容應該是MyServlet ，而不是MyServlet.class 。

其次，只使用一種方法來注冊servlet，過濾器或監聽器以使其清晰。 如果您更喜歡使用注釋將它們注冊到servlet容器。 你最好刪除web.xml中的servlet和servlet-mapping元素。 否則，您最好刪除java源代碼中的注釋。 如果要使用web.xml，則應將架構版本從2.4更新到3.0

最后，您的第二個問題來自Jetty WTP Eclipse插件可以通過嘗試這個來解決： websockets項目的jetty運行錯誤

解決方案2
 4  2012-01-30 07:12:56

您訪問該服務的方式可能是錯誤的。 如果我們觀察你正在部署的戰爭是MySite.war ，你使用的url是localhost:8080\\MyServlet\\Servlet

嘗試使用localhost:8080\\MySite\\Servlet

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