泽西岛HTTP 500错误

Question

I am trying to figure out the basics of REST and Jersey. I am following a Cruncify tutorial found here .

Here is the service I am using:

package com.crunchify.restjersey;

/**
* @author Crunchify.com
*/

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;

@Path("/ctofservice")
public class CtoFService {
@GET
@Produces("application/xml")
public String convertCtoF() {

    Double fahrenheit;
    Double celsius = 36.8;
    fahrenheit = ((celsius * 9) / 5) + 32;

    String result = "@Produces(\"application/xml\") Output: \n\nC to F Converter Output: \n\n" + fahrenheit;
    return "<ctofservice>" + "<celsius>" + celsius + "</celsius>" + "<ctofoutput>" + result + "</ctofoutput>" + "</ctofservice>";
}

@Path("{c}")
@GET
@Produces("application/xml")
public String convertCtoFfromInput(@PathParam("c") Double c) {
    Double fahrenheit;
    Double celsius = c;
    fahrenheit = ((celsius * 9) / 5) + 32;

    String result = "@Produces(\"application/xml\") Output: \n\nC to F Converter Output: \n\n" + fahrenheit;
    return "<ctofservice>" + "<celsius>" + celsius + "</celsius>" + "<ctofoutput>" + result + "</ctofoutput>" + "</ctofservice>";
}
}

Here is the 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_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<display-name>CrunchifyRESTJerseyExample</display-name>
<welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
</welcome-file-list>

<servlet>
    <servlet-name>Jersey Web Application</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>Jersey Web Application</servlet-name>
    <url-pattern>/crunchify/*</url-pattern>
</servlet-mapping>

Here is the pom.xml:

   <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>CrunchifyRESTJerseyExample</groupId>
  <artifactId>CrunchifyRESTJerseyExample</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.3</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.6</version>
        <configuration>
          <warSourceDirectory>WebContent</warSourceDirectory>
          <failOnMissingWebXml>false</failOnMissingWebXml>
        </configuration>
      </plugin>
    </plugins>
  </build>
  <dependencies>
    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-bundle</artifactId>
        <version>1.19.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-server</artifactId>
        <version>1.19.1</version>
    </dependency>
    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-core</artifactId>
        <version>1.19.1</version>
    </dependency>
    <dependency>
        <groupId>asm</groupId>
        <artifactId>asm</artifactId>
        <version>20041228.180559</version>
    </dependency>
    <dependency>
        <groupId>ai.x</groupId>
        <artifactId>play-json-extensions_2.11</artifactId>
        <version>0.8.0</version>
    </dependency>
  </dependencies>
</project>

And there error I'm getting is:

type Exception report

message Servlet.init() for servlet Jersey Web Application threw exception

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Servlet.init() for servlet Jersey Web Application threw exception
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:745)

The root cause is a JSON Exception. I am running this on a Tomcat 8.0 server. Any help would be appreciated. Thanks.

Answer 1

Init param where we specify all resource classes is missing in servlet container of web.xml. Please see below sample for the same.

<servlet>
    <servlet-name>Jersey Web Application</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
            <init-param>
                <param-name>jersey.config.server.provider.packages</param-name>
                <param-value>com.crunchify.restjersey;
                   com.fasterxml.jackson.jaxrs
                </param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>

When running in a Servlet 2.x then instead it is necessary to declare the Jersey specific servlet and pass the Application implementation class name as one of the servlet's init-param entries