単純なREST APIがHTTP 500を返す

Question

単純なHello World REST APIを作成しようとしています。私はIDEとしてIntelliJ IDEAを使用しています。 Tomcat 8.5.4をダウンロードしてローカルテストサーバーとして使用しました。それが問題なら、私はMacで開発しています。私はジャージーライブラリがインポートされている：ここで

は私のweb.xmlファイルである：ここで

<?xml version="1.0" encoding="UTF-8"?> 
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" 
     version="3.1"> 
    <display-name>HelloWorld</display-name> 
    <servlet> 
     <servlet-name>com.jamesshinevar.HelloWorld</servlet-name> 
     <init-param> 
      <param-name>jersey.config.server.provider.packages</param-name> 
      <param-value>com.jamesshinevar</param-value> 
     </init-param> 
    </servlet> 

    <servlet-mapping> 
     <servlet-name>com.jamesshinevar.HelloWorld</servlet-name> 
     <url-pattern>/api/*</url-pattern> 
    </servlet-mapping> 
</web-app> 

は私のクラスのコードです：

package com.jamesshinevar; 

import javax.ws.rs.GET; 
import javax.ws.rs.Path; 
import javax.ws.rs.Produces; 
import javax.ws.rs.core.MediaType; 

@Path("/test") 
public class HelloWorld { 
    @GET 
    @Produces(MediaType.TEXT_PLAIN) 
    public String hello(){ 
     return "Hello"; 
    } 
} 

私はこれを実行していますし、私はそれが次のように実行されていることを示す：

/Users/james/apache-tomcat-8.5.4/bin/catalina.sh run 
[2016-08-16 09:33:11,573] Artifact helloworldREST:war exploded: Server is not connected. Deploy is not available. 
16-Aug-2016 09:33:12.907 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server version:  Apache Tomcat/8.5.4 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server built:   Jul 6 2016 08:43:30 UTC 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Server number:   8.5.4.0 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Name:    Mac OS X 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log OS Version:   10.11.6 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Architecture:   x86_64 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Java Home:    /Library/Java/JavaVirtualMachines/jdk1.8.0_101.jdk/Contents/Home/jre 
16-Aug-2016 09:33:12.909 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Version:   1.8.0_101-b13 
16-Aug-2016 09:33:12.910 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log JVM Vendor:   Oracle Corporation 
16-Aug-2016 09:33:12.910 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_BASE:   /Users/james/Library/Caches/IntelliJIdea2016.2/tomcat/Tomcat_8_5_4_helloworldREST_4 
16-Aug-2016 09:33:12.910 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log CATALINA_HOME:   /Users/james/apache-tomcat-8.5.4 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.config.file=/Users/james/Library/Caches/IntelliJIdea2016.2/tomcat/Tomcat_8_5_4_helloworldREST_4/conf/logging.properties 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote= 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.port=1099 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.ssl=false 
16-Aug-2016 09:33:12.911 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcom.sun.management.jmxremote.authenticate=false 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.rmi.server.hostname=127.0.0.1 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djdk.tls.ephemeralDHKeySize=2048 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.base=/Users/james/Library/Caches/IntelliJIdea2016.2/tomcat/Tomcat_8_5_4_helloworldREST_4 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Dcatalina.home=/Users/james/apache-tomcat-8.5.4 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.startup.VersionLoggerListener.log Command line argument: -Djava.io.tmpdir=/Users/james/apache-tomcat-8.5.4/temp 
16-Aug-2016 09:33:12.912 INFO [main] org.apache.catalina.core.AprLifecycleListener.lifecycleEvent The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /Users/james/Library/Java/Extensions:/Library/Java/Extensions:/Network/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java:. 
16-Aug-2016 09:33:13.174 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["http-nio-8080"] 
16-Aug-2016 09:33:13.210 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read 
16-Aug-2016 09:33:13.214 INFO [main] org.apache.coyote.AbstractProtocol.init Initializing ProtocolHandler ["ajp-nio-8009"] 
16-Aug-2016 09:33:13.216 INFO [main] org.apache.tomcat.util.net.NioSelectorPool.getSharedSelector Using a shared selector for servlet write/read 
16-Aug-2016 09:33:13.216 INFO [main] org.apache.catalina.startup.Catalina.load Initialization processed in 802 ms 
16-Aug-2016 09:33:13.250 INFO [main] org.apache.catalina.core.StandardService.startInternal Starting service Catalina 
16-Aug-2016 09:33:13.250 INFO [main] org.apache.catalina.core.StandardEngine.startInternal Starting Servlet Engine: Apache Tomcat/8.5.4 
16-Aug-2016 09:33:13.259 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler [http-nio-8080] 
16-Aug-2016 09:33:13.267 INFO [main] org.apache.coyote.AbstractProtocol.start Starting ProtocolHandler [ajp-nio-8009] 
16-Aug-2016 09:33:13.268 INFO [main] org.apache.catalina.startup.Catalina.start Server startup in 51 ms 
Connected to server 
[2016-08-16 09:33:13,571] Artifact helloworldREST:war exploded: Artifact is being deployed, please wait... 
[2016-08-16 09:33:14,065] Artifact helloworldREST:war exploded: Artifact is deployed successfully 
[2016-08-16 09:33:14,066] Artifact helloworldREST:war exploded: Deploy took 494 milliseconds 
16-Aug-2016 09:33:23.264 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deploying web application directory /Users/james/apache-tomcat-8.5.4/webapps/manager 
16-Aug-2016 09:33:23.292 INFO [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory /Users/james/apache-tomcat-8.5.4/webapps/manager has finished in 28 ms 

私はURLへ行くしようとすると

私が取得：IntelliJのでTomcatのローカルホストログイン

は私が持っている：私はNullPointerExceptionが原因となっている理解していないよ

16-Aug-2016 09:35:39.773 SEVERE [http-nio-8080-exec-8] org.apache.catalina.core.StandardHostValve.invoke Exception Processing /helloworld/api/test 
java.lang.NullPointerException 
    at java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011) 
    at java.util.concurrent.ConcurrentHashMap.putIfAbsent(ConcurrentHashMap.java:1535) 
    at java.lang.ClassLoader.getClassLoadingLock(ClassLoader.java:463) 
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1151) 
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1118) 
    at org.apache.catalina.core.StandardWrapper.servletSecurityAnnotationScan(StandardWrapper.java:1139) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:510) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) 
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1110) 
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) 
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:785) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1425) 
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 
    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) 

500エラーが発生しています。私はそれが私の目の前であると確信していますが、私は私が見ているものを理解していないだけです。誰も私にこの作品を作る方法としていくつかのポインタを教えてもらえますか？これは十分に単純であるように思える。私は、単に "Hello"文字列を返すAPIが必要ですが、明らかに私は苦労しています。

Answer 1

あなたはcom.sun.jersey.spi.container.servlet.ServletContainerとして、web.xmlに<servlet-class>エントリを追加する必要がservlet-classエントリ

<?xml version="1.0" encoding="UTF-8"?> 
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" 
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
     xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" 
     version="3.1"> 
    <display-name>HelloWorld</display-name> 
    <servlet> 
     <servlet-name>com.jamesshinevar.HelloWorld</servlet-name> 
     <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class> 
     <init-param> 
      <param-name>jersey.config.server.provider.packages</param-name> 
      <param-value>com.jamesshinevar</param-value> 
     </init-param> 
    </servlet> 

    <servlet-mapping> 
     <servlet-name>com.jamesshinevar.HelloWorld</servlet-name> 
     <url-pattern>/api/*</url-pattern> 
    </servlet-mapping> 
</web-app> 

Answer 2

エラーはweb.xmlにあると思います。 mkyongに示すように：

<web-app id="WebApp_ID" version="2.4" 
    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"> 
    <display-name>Restful Web Application</display-name> 

    <servlet> 
     <servlet-name>jersey-serlvet</servlet-name> 
     <servlet-class> 
        com.sun.jersey.spi.container.servlet.ServletContainer 
       </servlet-class> 
     <init-param> 
      <param-name>com.sun.jersey.config.property.packages</param-name> 
      <param-value>com.jamesshinevar</param-value> 
     </init-param> 
     <load-on-startup>1</load-on-startup> 
    </servlet> 

    <servlet-mapping> 
     <servlet-name>jersey-serlvet</servlet-name> 
     <url-pattern>/api/*</url-pattern> 
    </servlet-mapping> 

</web-app> 

あなたが指定したクラスは、サーブレットではありません。サーブレットを提供し、注釈付きクラスにリクエストをマップするのはジャージーの仕事です。

Answer 3

が欠落しています。詳細については

、このチュートリアルを見てみましょう：https://www.ibm.com/developerworks/library/wa-aj-tomcat/